Cleanup: Fix comment style and check if they are valid or make sense.

12 files changed, 598 insertions, 774 deletions

diff --git a/source/blender/editors/space_sequencer/sequencer_add.c b/source/blender/editors/space_sequencer/sequencer_add.c
index 278fb9fb683..049f3d76b53 100644
--- a/source/blender/editors/space_sequencer/sequencer_add.c
+++ b/source/blender/editors/space_sequencer/sequencer_add.c
@@ -51,8 +51,7 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
-/* for menu/popup icons etc etc*/
-
+/* For menu, popup, icons, etc. */
 #include "ED_screen.h"
 #include "ED_sequencer.h"
 
@@ -67,16 +66,16 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
 
-/* own include */
+/* Own include. */
 #include "sequencer_intern.h"
 
 typedef struct SequencerAddData {
   ImageFormatData im_format;
 } SequencerAddData;
 
-/* Generic functions, reused by add strip operators */
+/* Generic functions, reused by add strip operators. */
 
-/* avoid passing multiple args and be more verbose */
+/* Avoid passing multiple args and be more verbose. */
 #define SEQPROP_STARTFRAME (1 << 0)
 #define SEQPROP_ENDFRAME (1 << 1)
 #define SEQPROP_NOPATHS (1 << 2)
@@ -101,7 +100,7 @@ static void sequencer_generic_props__internal(wmOperatorType *ot, int flag)
   }
 
   if (flag & SEQPROP_ENDFRAME) {
-    /* not usual since most strips have a fixed length */
+    /* Not usual since most strips have a fixed length. */
     RNA_def_int(ot->srna,
                 "frame_end",
                 0,
@@ -119,7 +118,7 @@ static void sequencer_generic_props__internal(wmOperatorType *ot, int flag)
   RNA_def_boolean(
       ot->srna, "replace_sel", 1, "Replace Selection", "Replace the current selection");
 
-  /* only for python scripts which import strips and place them after */
+  /* Only for python scripts which import strips and place them after. */
   prop = RNA_def_boolean(
       ot->srna, "overlap", 0, "Allow Overlap", "Don't correct overlap on new sequence strips");
   RNA_def_property_flag(prop, PROP_HIDDEN);
@@ -175,7 +174,7 @@ static void sequencer_generic_invoke_xy__internal(bContext *C, wmOperator *op, i
 
   int cfra = (int)CFRA;
 
-  /* effect strips don't need a channel initialized from the mouse */
+  /* Effect strips don't need a channel initialized from the mouse. */
   if (!(flag & SEQPROP_NOCHAN) && RNA_struct_property_is_set(op->ptr, "channel") == 0) {
     RNA_int_set(op->ptr, "channel", sequencer_generic_invoke_xy_guess_channel(C, type));
   }
@@ -203,18 +202,17 @@ static void seq_load_operator_info(SeqLoadInfo *seq_load, bContext *C, wmOperato
   memset(seq_load, 0, sizeof(SeqLoadInfo));
 
   seq_load->start_frame = RNA_int_get(op->ptr, "frame_start");
-  seq_load->end_frame = seq_load->start_frame; /* un-set */
-
+  seq_load->end_frame = seq_load->start_frame;
   seq_load->channel = RNA_int_get(op->ptr, "channel");
-  seq_load->len = 1;  // images only, if endframe isn't set!
+  seq_load->len = 1;
 
   if ((prop = RNA_struct_find_property(op->ptr, "filepath"))) {
-    /* full path, file is set by the caller */
+    /* Full path, file is set by the caller. */
     RNA_property_string_get(op->ptr, prop, seq_load->path);
     is_file = 1;
   }
   else if ((prop = RNA_struct_find_property(op->ptr, "directory"))) {
-    /* full path, file is set by the caller */
+    /* Full path, file is set by the caller. */
     RNA_property_string_get(op->ptr, prop, seq_load->path);
     is_file = 0;
   }
@@ -252,15 +250,13 @@ static void seq_load_operator_info(SeqLoadInfo *seq_load, bContext *C, wmOperato
     seq_load->flag |= SEQ_LOAD_SYNC_FPS;
   }
 
-  /* always use this for ops */
+  /* Create consecutive array of strips. */
   seq_load->flag |= SEQ_LOAD_FRAME_ADVANCE;
 
   if (is_file == 1) {
     BLI_strncpy(seq_load->name, BLI_path_basename(seq_load->path), sizeof(seq_load->name));
   }
   else if ((prop = RNA_struct_find_property(op->ptr, "files"))) {
-    /* used for image strip */
-    /* best guess, first images name */
     RNA_PROP_BEGIN (op->ptr, itemptr, prop) {
       char *name = RNA_string_get_alloc(&itemptr, "name", NULL, 0);
       BLI_strncpy(seq_load->name, name, sizeof(seq_load->name));
@@ -278,9 +274,6 @@ static void seq_load_operator_info(SeqLoadInfo *seq_load, bContext *C, wmOperato
 
       seq_load->views_format = imf->views_format;
       seq_load->flag |= SEQ_USE_VIEWS;
-
-      /* operator custom data is always released after the SeqLoadInfo,
-       * no need to handle the memory here */
       seq_load->stereo3d_format = &imf->stereo3d_format;
     }
   }
@@ -332,22 +325,17 @@ static bool seq_effect_add_properties_poll(const bContext *UNUSED(C),
   return true;
 }
 
-/* add scene operator */
 static int sequencer_add_scene_strip_exec(bContext *C, wmOperator *op)
 {
   Main *bmain = CTX_data_main(C);
   Scene *scene = CTX_data_scene(C);
   Editing *ed = BKE_sequencer_editing_get(scene, true);
-
   Scene *sce_seq;
+  Sequence *seq;
 
-  Sequence *seq; /* generic strip vars */
-
-  int start_frame, channel; /* operator props */
-
+  int start_frame, channel;
   start_frame = RNA_int_get(op->ptr, "frame_start");
   channel = RNA_int_get(op->ptr, "channel");
-
   sce_seq = BLI_findlink(&bmain->scenes, RNA_enum_get(op->ptr, "scene"));
 
   if (sce_seq == NULL) {
@@ -356,11 +344,8 @@ static int sequencer_add_scene_strip_exec(bContext *C, wmOperator *op)
   }
 
   seq = BKE_sequence_alloc(ed->seqbasep, start_frame, channel, SEQ_TYPE_SCENE);
-  seq->blend_mode = SEQ_TYPE_CROSS; /* so alpha adjustment fade to the strip below */
-
+  seq->blend_mode = SEQ_TYPE_CROSS;
   seq->scene = sce_seq;
-
-  /* basic defaults */
   seq->len = sce_seq->r.efra - sce_seq->r.sfra + 1;
 
   BLI_strncpy(seq->name + 2, sce_seq->id.name + 2, sizeof(seq->name) - 2);
@@ -388,26 +373,23 @@ static int sequencer_add_scene_strip_invoke(bContext *C, wmOperator *op, const w
 
   sequencer_generic_invoke_xy__internal(C, op, 0, SEQ_TYPE_SCENE);
   return sequencer_add_scene_strip_exec(C, op);
-  // needs a menu
-  // return WM_menu_invoke(C, op, event);
 }
 
 void SEQUENCER_OT_scene_strip_add(struct wmOperatorType *ot)
 {
   PropertyRNA *prop;
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Add Scene Strip";
   ot->idname = "SEQUENCER_OT_scene_strip_add";
   ot->description = "Add a strip to the sequencer using a blender scene as a source";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_add_scene_strip_invoke;
   ot->exec = sequencer_add_scene_strip_exec;
-
   ot->poll = ED_operator_sequencer_active_editable;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   sequencer_generic_props__internal(ot, SEQPROP_STARTFRAME);
@@ -417,22 +399,17 @@ void SEQUENCER_OT_scene_strip_add(struct wmOperatorType *ot)
   ot->prop = prop;
 }
 
-/* add movieclip operator */
 static int sequencer_add_movieclip_strip_exec(bContext *C, wmOperator *op)
 {
   Main *bmain = CTX_data_main(C);
   Scene *scene = CTX_data_scene(C);
   Editing *ed = BKE_sequencer_editing_get(scene, true);
-
   MovieClip *clip;
+  Sequence *seq;
 
-  Sequence *seq; /* generic strip vars */
-
-  int start_frame, channel; /* operator props */
-
+  int start_frame, channel;
   start_frame = RNA_int_get(op->ptr, "frame_start");
   channel = RNA_int_get(op->ptr, "channel");
-
   clip = BLI_findlink(&bmain->movieclips, RNA_enum_get(op->ptr, "clip"));
 
   if (clip == NULL) {
@@ -443,12 +420,10 @@ static int sequencer_add_movieclip_strip_exec(bContext *C, wmOperator *op)
   seq = BKE_sequence_alloc(ed->seqbasep, start_frame, channel, SEQ_TYPE_MOVIECLIP);
   seq->blend_mode = SEQ_TYPE_CROSS;
   seq->clip = clip;
+  seq->len = BKE_movieclip_get_duration(clip);
 
   id_us_ensure_real(&seq->clip->id);
 
-  /* basic defaults */
-  seq->len = BKE_movieclip_get_duration(clip);
-
   BLI_strncpy(seq->name + 2, clip->id.name + 2, sizeof(seq->name) - 2);
   BKE_sequence_base_unique_name_recursive(&ed->seqbase, seq);
 
@@ -473,26 +448,23 @@ static int sequencer_add_movieclip_strip_invoke(bContext *C, wmOperator *op, con
 
   sequencer_generic_invoke_xy__internal(C, op, 0, SEQ_TYPE_MOVIECLIP);
   return sequencer_add_movieclip_strip_exec(C, op);
-  // needs a menu
-  // return WM_menu_invoke(C, op, event);
 }
 
 void SEQUENCER_OT_movieclip_strip_add(struct wmOperatorType *ot)
 {
   PropertyRNA *prop;
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Add MovieClip Strip";
   ot->idname = "SEQUENCER_OT_movieclip_strip_add";
   ot->description = "Add a movieclip strip to the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_add_movieclip_strip_invoke;
   ot->exec = sequencer_add_movieclip_strip_exec;
-
   ot->poll = ED_operator_sequencer_active_editable;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   sequencer_generic_props__internal(ot, SEQPROP_STARTFRAME);
@@ -508,16 +480,12 @@ static int sequencer_add_mask_strip_exec(bContext *C, wmOperator *op)
   Main *bmain = CTX_data_main(C);
   Scene *scene = CTX_data_scene(C);
   Editing *ed = BKE_sequencer_editing_get(scene, true);
-
   Mask *mask;
+  Sequence *seq;
 
-  Sequence *seq; /* generic strip vars */
-
-  int start_frame, channel; /* operator props */
-
+  int start_frame, channel;
   start_frame = RNA_int_get(op->ptr, "frame_start");
   channel = RNA_int_get(op->ptr, "channel");
-
   mask = BLI_findlink(&bmain->masks, RNA_enum_get(op->ptr, "mask"));
 
   if (mask == NULL) {
@@ -528,12 +496,10 @@ static int sequencer_add_mask_strip_exec(bContext *C, wmOperator *op)
   seq = BKE_sequence_alloc(ed->seqbasep, start_frame, channel, SEQ_TYPE_MASK);
   seq->blend_mode = SEQ_TYPE_CROSS;
   seq->mask = mask;
+  seq->len = BKE_mask_get_duration(mask);
 
   id_us_ensure_real(&seq->mask->id);
 
-  /* basic defaults */
-  seq->len = BKE_mask_get_duration(mask);
-
   BLI_strncpy(seq->name + 2, mask->id.name + 2, sizeof(seq->name) - 2);
   BKE_sequence_base_unique_name_recursive(&ed->seqbase, seq);
 
@@ -558,26 +524,23 @@ static int sequencer_add_mask_strip_invoke(bContext *C, wmOperator *op, const wm
 
   sequencer_generic_invoke_xy__internal(C, op, 0, SEQ_TYPE_MASK);
   return sequencer_add_mask_strip_exec(C, op);
-  // needs a menu
-  // return WM_menu_invoke(C, op, event);
 }
 
 void SEQUENCER_OT_mask_strip_add(struct wmOperatorType *ot)
 {
   PropertyRNA *prop;
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Add Mask Strip";
   ot->idname = "SEQUENCER_OT_mask_strip_add";
   ot->description = "Add a mask strip to the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_add_mask_strip_invoke;
   ot->exec = sequencer_add_mask_strip_exec;
-
   ot->poll = ED_operator_sequencer_active_editable;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   sequencer_generic_props__internal(ot, SEQPROP_STARTFRAME);
@@ -589,7 +552,7 @@ void SEQUENCER_OT_mask_strip_add(struct wmOperatorType *ot)
 
 static int sequencer_add_generic_strip_exec(bContext *C, wmOperator *op, SeqLoadFn seq_load_fn)
 {
-  Scene *scene = CTX_data_scene(C); /* only for sound */
+  Scene *scene = CTX_data_scene(C);
   Editing *ed = BKE_sequencer_editing_get(scene, true);
   SeqLoadInfo seq_load;
   int tot_files;
@@ -603,7 +566,6 @@ static int sequencer_add_generic_strip_exec(bContext *C, wmOperator *op, SeqLoad
   tot_files = RNA_property_collection_length(op->ptr, RNA_struct_find_property(op->ptr, "files"));
 
   if (tot_files > 1) {
-    /* multiple files */
     char dir_only[FILE_MAX];
     char file_only[FILE_MAX];
 
@@ -614,7 +576,7 @@ static int sequencer_add_generic_strip_exec(bContext *C, wmOperator *op, SeqLoad
       RNA_string_get(&itemptr, "name", file_only);
       BLI_join_dirfile(seq_load.path, sizeof(seq_load.path), dir_only, file_only);
 
-      /* Set seq_load.name, else all video/audio files get the same name! ugly! */
+      /* Set seq_load.name, otherwise all video/audio files get the same name. */
       BLI_strncpy(seq_load.name, file_only, sizeof(seq_load.name));
 
       seq = seq_load_fn(C, ed->seqbasep, &seq_load);
@@ -627,11 +589,10 @@ static int sequencer_add_generic_strip_exec(bContext *C, wmOperator *op, SeqLoad
     }
     RNA_END;
   }
-  else {
+  else { /* Single file./ */
     Sequence *seq;
-
-    /* single file */
     seq = seq_load_fn(C, ed->seqbasep, &seq_load);
+
     if (seq) {
       sequencer_add_apply_overlap(C, op, seq);
       if (seq_load.seq_sound) {
@@ -658,7 +619,6 @@ static int sequencer_add_generic_strip_exec(bContext *C, wmOperator *op, SeqLoad
   return OPERATOR_FINISHED;
 }
 
-/* add sequencer operators */
 static void sequencer_add_init(bContext *UNUSED(C), wmOperator *op)
 {
   op->customdata = MEM_callocN(sizeof(SequencerAddData), __func__);
@@ -673,8 +633,8 @@ static void sequencer_add_cancel(bContext *UNUSED(C), wmOperator *op)
 }
 
 static bool sequencer_add_draw_check_fn(PointerRNA *UNUSED(ptr),
-                                          PropertyRNA *prop,
-                                          void *UNUSED(user_data))
+                                        PropertyRNA *prop,
+                                        void *UNUSED(user_data))
 {
   const char *prop_id = RNA_property_identifier(prop);
 
@@ -682,7 +642,6 @@ static bool sequencer_add_draw_check_fn(PointerRNA *UNUSED(ptr),
            STREQ(prop_id, "filename"));
 }
 
-/* add movie operator */
 static int sequencer_add_movie_strip_exec(bContext *C, wmOperator *op)
 {
   return sequencer_add_generic_strip_exec(C, op, BKE_sequencer_add_movie_strip);
@@ -696,20 +655,12 @@ static int sequencer_add_movie_strip_invoke(bContext *C,
   Scene *scene = CTX_data_scene(C);
   Editing *ed = BKE_sequencer_editing_get(scene, false);
 
-  /* only enable "use_framerate" if there aren't any existing strips
-   * - When there are no strips yet, there is no harm in enabling this,
-   *   and it makes the single-strip case really nice for casual users
-   * - When there are strips, it's best we don't touch the framerate,
-   *   as all hell may break loose (e.g. audio strips start overlapping
-   *   and can't be restored)
-   * - These initial guesses can still be manually overridden by users
-   *   from the modal options panel
-   */
+  /* Only enable "use_framerate" if there aren't any existing strips, unless overriden by user. */
   if (ed && ed->seqbasep && ed->seqbasep->first) {
     RNA_boolean_set(op->ptr, "use_framerate", false);
   }
 
-  /* This is for drag and drop */
+  /* This is for drag and drop. */
   if ((RNA_struct_property_is_set(op->ptr, "files") && RNA_collection_length(op->ptr, "files")) ||
       RNA_struct_property_is_set(op->ptr, "filepath")) {
     sequencer_generic_invoke_xy__internal(C, op, SEQPROP_NOPATHS, SEQ_TYPE_MOVIE);
@@ -717,17 +668,14 @@ static int sequencer_add_movie_strip_invoke(bContext *C,
   }
 
   sequencer_generic_invoke_xy__internal(C, op, 0, SEQ_TYPE_MOVIE);
-
   sequencer_add_init(C, op);
 
-  /* show multiview save options only if scene has multiviews */
+  /* Show multiview save options only if scene use multiview. */
   prop = RNA_struct_find_property(op->ptr, "show_multiview");
   RNA_property_boolean_set(op->ptr, prop, (scene->r.scemode & R_MULTIVIEW) != 0);
 
   WM_event_add_fileselect(C, op);
   return OPERATOR_RUNNING_MODAL;
-
-  // return sequencer_add_movie_strip_exec(C, op);
 }
 
 static void sequencer_add_draw(bContext *UNUSED(C), wmOperator *op)
@@ -737,15 +685,15 @@ static void sequencer_add_draw(bContext *UNUSED(C), wmOperator *op)
   ImageFormatData *imf = &sad->im_format;
   PointerRNA imf_ptr, ptr;
 
-  /* main draw call */
+  /* Main draw call. */
   RNA_pointer_create(NULL, op->type->srna, op->properties, &ptr);
   uiDefAutoButsRNA(
       layout, &ptr, sequencer_add_draw_check_fn, NULL, NULL, UI_BUT_LABEL_ALIGN_NONE, false);
 
-  /* image template */
+  /* Image template. */
   RNA_pointer_create(NULL, &RNA_ImageFormatSettings, imf, &imf_ptr);
 
-  /* multiview template */
+  /* Multiview template. */
   if (RNA_boolean_get(op->ptr, "show_multiview")) {
     uiTemplateImageFormatViews(layout, &imf_ptr, op->ptr);
   }
@@ -754,20 +702,19 @@ static void sequencer_add_draw(bContext *UNUSED(C), wmOperator *op)
 void SEQUENCER_OT_movie_strip_add(struct wmOperatorType *ot)
 {
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Add Movie Strip";
   ot->idname = "SEQUENCER_OT_movie_strip_add";
   ot->description = "Add a movie strip to the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_add_movie_strip_invoke;
   ot->exec = sequencer_add_movie_strip_exec;
   ot->cancel = sequencer_add_cancel;
   ot->ui = sequencer_add_draw;
-
   ot->poll = ED_operator_sequencer_active_editable;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   WM_operator_properties_filesel(ot,
@@ -787,8 +734,6 @@ void SEQUENCER_OT_movie_strip_add(struct wmOperatorType *ot)
                   "Use framerate from the movie to keep sound and video in sync");
 }
 
-/* add sound operator */
-
 static int sequencer_add_sound_strip_exec(bContext *C, wmOperator *op)
 {
   return sequencer_add_generic_strip_exec(C, op, BKE_sequencer_add_sound_strip);
@@ -798,7 +743,7 @@ static int sequencer_add_sound_strip_invoke(bContext *C,
                                             wmOperator *op,
                                             const wmEvent *UNUSED(event))
 {
-  /* This is for drag and drop */
+  /* This is for drag and drop. */
   if ((RNA_struct_property_is_set(op->ptr, "files") && RNA_collection_length(op->ptr, "files")) ||
       RNA_struct_property_is_set(op->ptr, "filepath")) {
     sequencer_generic_invoke_xy__internal(C, op, SEQPROP_NOPATHS, SEQ_TYPE_SOUND_RAM);
@@ -809,25 +754,22 @@ static int sequencer_add_sound_strip_invoke(bContext *C,
 
   WM_event_add_fileselect(C, op);
   return OPERATOR_RUNNING_MODAL;
-
-  // return sequencer_add_sound_strip_exec(C, op);
 }
 
 void SEQUENCER_OT_sound_strip_add(struct wmOperatorType *ot)
 {
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Add Sound Strip";
   ot->idname = "SEQUENCER_OT_sound_strip_add";
   ot->description = "Add a sound strip to the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_add_sound_strip_invoke;
   ot->exec = sequencer_add_sound_strip_exec;
-
   ot->poll = ED_operator_sequencer_active_editable;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   WM_operator_properties_filesel(ot,
@@ -854,7 +796,6 @@ int sequencer_image_seq_get_minmax_frame(wmOperator *op,
   RNA_BEGIN (op->ptr, itemptr, "files") {
     char *filename;
     int frame;
-    /* just get the first filename */
     filename = RNA_string_get_alloc(&itemptr, "name", NULL, 0);
 
     if (filename) {
@@ -885,7 +826,6 @@ void sequencer_image_seq_reserve_frames(
   int i;
   char *filename = NULL;
   RNA_BEGIN (op->ptr, itemptr, "files") {
-    /* just get the first filename */
     filename = RNA_string_get_alloc(&itemptr, "name", NULL, 0);
     break;
   }
@@ -894,7 +834,7 @@ void sequencer_image_seq_reserve_frames(
   if (filename) {
     char ext[PATH_MAX];
     char filename_stripped[PATH_MAX];
-    /* strip the frame from filename and substitute with # */
+    /* Strip the frame from filename and substitute with `#`. */
     BLI_path_frame_strip(filename, ext);
 
     for (i = 0; i < len; i++, se++) {
@@ -907,23 +847,20 @@ void sequencer_image_seq_reserve_frames(
   }
 }
 
-/* add image operator */
 static int sequencer_add_image_strip_exec(bContext *C, wmOperator *op)
 {
   int minframe, numdigits;
-  /* cant use the generic function for this */
-  Scene *scene = CTX_data_scene(C); /* only for sound */
+  Scene *scene = CTX_data_scene(C);
   Editing *ed = BKE_sequencer_editing_get(scene, true);
   SeqLoadInfo seq_load;
   Sequence *seq;
-
   Strip *strip;
   StripElem *se;
   const bool use_placeholders = RNA_boolean_get(op->ptr, "use_placeholders");
 
   seq_load_operator_info(&seq_load, C, op);
 
-  /* images are unique in how they handle this - 1 per strip elem */
+  /* Images are unique in how they handle this - 1 per strip elem. */
   if (use_placeholders) {
     seq_load.len = sequencer_image_seq_get_minmax_frame(
         op, seq_load.start_frame, &minframe, &numdigits);
@@ -941,11 +878,10 @@ static int sequencer_add_image_strip_exec(bContext *C, wmOperator *op)
     ED_sequencer_deselect_all(scene);
   }
 
-  /* main adding function */
+  /* Main adding function. */
   seq = BKE_sequencer_add_image_strip(C, ed->seqbasep, &seq_load);
   strip = seq->strip;
   se = strip->stripdata;
-
   seq->blend_mode = SEQ_TYPE_ALPHAOVER;
 
   if (use_placeholders) {
@@ -968,21 +904,18 @@ static int sequencer_add_image_strip_exec(bContext *C, wmOperator *op)
   }
 
   BKE_sequence_init_colorspace(seq);
-
   BKE_sequence_calc_disp(scene, seq);
-
   BKE_sequencer_sort(scene);
 
-  /* last active name */
+  /* Last active name. */
   BLI_strncpy(ed->act_imagedir, strip->dir, sizeof(ed->act_imagedir));
-
   sequencer_add_apply_overlap(C, op, seq);
 
   if (op->customdata) {
     MEM_freeN(op->customdata);
   }
-  BKE_sequence_invalidate_cache_composite(scene, seq);
 
+  BKE_sequence_invalidate_cache_composite(scene, seq);
   DEG_id_tag_update(&scene->id, ID_RECALC_SEQUENCER_STRIPS);
   WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, scene);
 
@@ -996,7 +929,7 @@ static int sequencer_add_image_strip_invoke(bContext *C,
   PropertyRNA *prop;
   Scene *scene = CTX_data_scene(C);
 
-  /* drag drop has set the names */
+  /* Name set already by drag and drop. */
   if (RNA_struct_property_is_set(op->ptr, "files") && RNA_collection_length(op->ptr, "files")) {
     sequencer_generic_invoke_xy__internal(
         C, op, SEQPROP_ENDFRAME | SEQPROP_NOPATHS, SEQ_TYPE_IMAGE);
@@ -1004,10 +937,9 @@ static int sequencer_add_image_strip_invoke(bContext *C,
   }
 
   sequencer_generic_invoke_xy__internal(C, op, SEQPROP_ENDFRAME, SEQ_TYPE_IMAGE);
-
   sequencer_add_init(C, op);
 
-  /* show multiview save options only if scene has multiviews */
+  /* Show multiview save options only if scene use multiview. */
   prop = RNA_struct_find_property(op->ptr, "show_multiview");
   RNA_property_boolean_set(op->ptr, prop, (scene->r.scemode & R_MULTIVIEW) != 0);
 
@@ -1018,20 +950,19 @@ static int sequencer_add_image_strip_invoke(bContext *C,
 void SEQUENCER_OT_image_strip_add(struct wmOperatorType *ot)
 {
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Add Image Strip";
   ot->idname = "SEQUENCER_OT_image_strip_add";
   ot->description = "Add an image or image sequence to the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_add_image_strip_invoke;
   ot->exec = sequencer_add_image_strip_exec;
   ot->cancel = sequencer_add_cancel;
   ot->ui = sequencer_add_draw;
-
   ot->poll = ED_operator_sequencer_active_editable;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   WM_operator_properties_filesel(ot,
@@ -1051,65 +982,54 @@ void SEQUENCER_OT_image_strip_add(struct wmOperatorType *ot)
                   "Use placeholders for missing frames of the strip");
 }
 
-/* add_effect_strip operator */
 static int sequencer_add_effect_strip_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
   Editing *ed = BKE_sequencer_editing_get(scene, true);
-
-  Sequence *seq; /* generic strip vars */
+  Sequence *seq;
   struct SeqEffectHandle sh;
-
-  int start_frame, end_frame, channel, type; /* operator props */
-
   Sequence *seq1, *seq2, *seq3;
   const char *error_msg;
+  int start_frame, end_frame, channel, type;
 
   start_frame = RNA_int_get(op->ptr, "frame_start");
   end_frame = RNA_int_get(op->ptr, "frame_end");
   channel = RNA_int_get(op->ptr, "channel");
-
   type = RNA_enum_get(op->ptr, "type");
 
-  // XXX move to invoke
   if (!seq_effect_find_selected(scene, NULL, type, &seq1, &seq2, &seq3, &error_msg)) {
     BKE_report(op->reports, RPT_ERROR, error_msg);
     return OPERATOR_CANCELLED;
   }
 
-  /* If seq1 is NULL and no error was raised it means the seq is standalone
-   * (like color strips) and we need to check its start and end frames are valid */
+  /* Check its start and end frames are valid. */
   if (seq1 == NULL && end_frame <= start_frame) {
     end_frame = start_frame + 1;
     RNA_int_set(op->ptr, "frame_end", end_frame);
   }
 
   seq = BKE_sequence_alloc(ed->seqbasep, start_frame, channel, type);
-
   BLI_strncpy(seq->name + 2, BKE_sequence_give_name(seq), sizeof(seq->name) - 2);
   BKE_sequence_base_unique_name_recursive(&ed->seqbase, seq);
 
   sh = BKE_sequence_get_effect(seq);
-
+  sh.init(seq);
   seq->seq1 = seq1;
   seq->seq2 = seq2;
   seq->seq3 = seq3;
 
-  sh.init(seq);
-
-  if (!seq1) { /* effect has no deps */
-    seq->len = 1;
+  if (!seq1) {
+    seq->len = 1; /* Effect is generator, set non zero length. */
     BKE_sequence_tx_set_final_right(seq, end_frame);
   }
 
   seq->flag |= SEQ_USE_EFFECT_DEFAULT_FADE;
-
   BKE_sequence_calc(scene, seq);
 
   if (seq->type == SEQ_TYPE_COLOR) {
     SolidColorVars *colvars = (SolidColorVars *)seq->effectdata;
     RNA_float_get_array(op->ptr, "color", colvars->col);
-    seq->blend_mode = SEQ_TYPE_CROSS; /* so alpha adjustment fade to the strip below */
+    seq->blend_mode = SEQ_TYPE_CROSS;
   }
   else if (seq->type == SEQ_TYPE_ADJUSTMENT) {
     seq->blend_mode = SEQ_TYPE_CROSS;
@@ -1118,8 +1038,7 @@ static int sequencer_add_effect_strip_exec(bContext *C, wmOperator *op)
     seq->blend_mode = SEQ_TYPE_ALPHAOVER;
   }
 
-  /* an unset channel is a special case where we automatically go above
-   * the other strips. */
+  /* Set channel.*/
   if (!RNA_struct_property_is_set(op->ptr, "channel")) {
     if (seq->seq1) {
       int chan = max_iii(seq->seq1 ? seq->seq1->machine : 0,
@@ -1134,20 +1053,16 @@ static int sequencer_add_effect_strip_exec(bContext *C, wmOperator *op)
   sequencer_add_apply_replace_sel(C, op, seq);
   sequencer_add_apply_overlap(C, op, seq);
 
-  BKE_sequencer_update_changed_seq_and_deps(scene, seq, 1, 1); /* runs BKE_sequence_calc */
-
-  /* not sure if this is needed with update_changed_seq_and_deps.
-   * it was NOT called in blender 2.4x, but wont hurt */
+  BKE_sequencer_update_changed_seq_and_deps(scene, seq, 1, 1); /* Runs BKE_sequence_calc. */
   BKE_sequencer_sort(scene);
-  BKE_sequence_invalidate_cache_composite(scene, seq);
 
+  BKE_sequence_invalidate_cache_composite(scene, seq);
   DEG_id_tag_update(&scene->id, ID_RECALC_SEQUENCER_STRIPS);
   WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, scene);
 
   return OPERATOR_FINISHED;
 }
 
-/* add color */
 static int sequencer_add_effect_strip_invoke(bContext *C,
                                              wmOperator *op,
                                              const wmEvent *UNUSED(event))
@@ -1159,10 +1074,8 @@ static int sequencer_add_effect_strip_invoke(bContext *C,
   if (is_type_set) {
     type = RNA_enum_get(op->ptr, "type");
 
-    /* when invoking an effect strip which uses inputs,
-     * skip initializing the channel from the mouse.
-     * Instead leave the property unset so exec() initializes it to be
-     * above the strips its applied to. */
+    /* When invoking an effect strip which uses inputs, skip initializing the channel from the
+     * mouse. */
     if (BKE_sequence_effect_get_num_inputs(type) != 0) {
       prop_flag |= SEQPROP_NOCHAN;
     }
@@ -1177,19 +1090,18 @@ void SEQUENCER_OT_effect_strip_add(struct wmOperatorType *ot)
 {
   PropertyRNA *prop;
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Add Effect Strip";
   ot->idname = "SEQUENCER_OT_effect_strip_add";
   ot->description = "Add an effect to the sequencer, most are applied on top of existing strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_add_effect_strip_invoke;
   ot->exec = sequencer_add_effect_strip_exec;
-
   ot->poll = ED_operator_sequencer_active_editable;
   ot->poll_property = seq_effect_add_properties_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   RNA_def_enum(ot->srna,
diff --git a/source/blender/editors/space_sequencer/sequencer_buttons.c b/source/blender/editors/space_sequencer/sequencer_buttons.c
index a2568e2e827..dce8aa16985 100644
--- a/source/blender/editors/space_sequencer/sequencer_buttons.c
+++ b/source/blender/editors/space_sequencer/sequencer_buttons.c
@@ -54,7 +54,7 @@ static bool sequencer_grease_pencil_panel_poll(const bContext *C, PanelType *UNU
 {
   SpaceSeq *sseq = CTX_wm_space_seq(C);
 
-  /* don't show the gpencil if we are not showing the image */
+  /* Don't show the gpencil if we are not showing the image. */
   return ED_space_sequencer_check_show_imbuf(sseq);
 }
 #endif
diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index db045b65d3f..2887113bdbe 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -79,20 +79,17 @@
 
 #include "MEM_guardedalloc.h"
 
-/* own include */
+/* Own include. */
 #include "sequencer_intern.h"
 
 #define SEQ_LEFTHANDLE 1
 #define SEQ_RIGHTHANDLE 2
-
 #define SEQ_HANDLE_SIZE 8.0f
-
 #define SEQ_SCROLLER_TEXT_OFFSET 8
-
 #define MUTE_ALPHA 120
 
 /* Note, Don't use SEQ_BEGIN/SEQ_END while drawing!
- * it messes up transform, - Campbell */
+ * it messes up transform. */
 #undef SEQ_BEGIN
 #undef SEQP_BEGIN
 #undef SEQ_END
@@ -141,7 +138,7 @@ void color3ubv_from_seq(Scene *curscene, Sequence *seq, uchar col[3])
       col[2] = 130;
       break;
 
-    /* effects */
+    /* Effects. */
     case SEQ_TYPE_TRANSFORM:
     case SEQ_TYPE_SPEED:
     case SEQ_TYPE_ADD:
@@ -234,13 +231,10 @@ static void draw_seq_waveform(View2D *v2d,
                               float y2,
                               float stepsize)
 {
-  /*
-   * x1 is the starting x value to draw the wave,
-   * x2 the end x value, same for y1 and y2
-   * stepsize is width of a pixel.
-   */
+  /* X1, x2 is the starting and end X value to draw the wave, same for y1 and y2.
+   * Stepsize is width of a pixel. */
 
-  /* offset x1 and x2 values, to match view min/max, if strip is out of bounds */
+  /* Offset x1 and x2 values, to match view min/max, if strip is out of bounds. */
   int x1_offset = max_ff(v2d->cur.xmin, x1);
   int x2_offset = min_ff(v2d->cur.xmax + 1.0f, x2);
 
@@ -254,8 +248,6 @@ static void draw_seq_waveform(View2D *v2d,
     float volume = seq->volume;
     float value1, value2;
     bSound *sound = seq->sound;
-    FCurve *fcu = id_data_find_fcurve(&scene->id, seq, &RNA_Sequence, "volume", 0, NULL);
-
     SoundWaveform *waveform;
 
     if (length < 2) {
@@ -265,7 +257,7 @@ static void draw_seq_waveform(View2D *v2d,
     BLI_spin_lock(sound->spinlock);
     if (!sound->waveform) {
       if (!(sound->tags & SOUND_TAGS_WAVEFORM_LOADING)) {
-        /* prevent sounds from reloading */
+        /* Prevent sounds from reloading. */
         sound->tags |= SOUND_TAGS_WAVEFORM_LOADING;
         BLI_spin_unlock(sound->spinlock);
         sequencer_preview_add_sound(C, seq);
@@ -273,15 +265,14 @@ static void draw_seq_waveform(View2D *v2d,
       else {
         BLI_spin_unlock(sound->spinlock);
       }
-      return; /* nothing to draw */
+      return; /* Nothing to draw. */
     }
     BLI_spin_unlock(sound->spinlock);
 
     waveform = sound->waveform;
 
+    /* Waveform could not be built. */
     if (waveform->length == 0) {
-      /* BKE_sound_read_waveform() set an empty SoundWaveform data in case it cannot generate a
-       * valid one. See T45726. */
       return;
     }
 
@@ -299,6 +290,9 @@ static void draw_seq_waveform(View2D *v2d,
       return;
     }
 
+    /* Fcurve lookup is quite expensive, so do this after precondition. */
+    FCurve *fcu = id_data_find_fcurve(&scene->id, seq, &RNA_Sequence, "volume", 0, NULL);
+
     GPU_blend(true);
     GPUVertFormat *format = immVertexFormat();
     uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
@@ -325,7 +319,7 @@ static void draw_seq_waveform(View2D *v2d,
         }
       }
       else if (p + 1 < waveform->length) {
-        /* use simple linear interpolation */
+        /* Use simple linear interpolation. */
         float f = sampleoffset - p;
         value1 = (1.0f - f) * value1 + f * waveform->data[p * 3 + 3];
         value2 = (1.0f - f) * value2 + f * waveform->data[p * 3 + 4];
@@ -361,10 +355,6 @@ static void draw_seq_waveform(View2D *v2d,
 
 static void drawmeta_contents(Scene *scene, Sequence *seqm, float x1, float y1, float x2, float y2)
 {
-  /* note: this used to use SEQ_BEGIN/SEQ_END, but it messes up the
-   * seq->depth value, (needed by transform when doing overlap checks)
-   * so for now, just use the meta's immediate children, could be fixed but
-   * its only drawing - campbell */
   Sequence *seq;
   uchar col[4];
 
@@ -400,12 +390,12 @@ static void drawmeta_contents(Scene *scene, Sequence *seqm, float x1, float y1,
   chan_range = (chan_max - chan_min) + 1;
   draw_height = draw_range / chan_range;
 
-  col[3] = 196; /* alpha, used for all meta children */
+  col[3] = 196; /* Alpha, used for all meta children. */
 
   uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
-
   immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
 
+  /* Draw only immediate children (1 level depth). */
   for (seq = seqbase->first; seq; seq = seq->next) {
     const int startdisp = seq->startdisp + offset;
     const int enddisp = seq->enddisp + offset;
@@ -433,7 +423,7 @@ static void drawmeta_contents(Scene *scene, Sequence *seqm, float x1, float y1,
 
       immUniformColor4ubv(col);
 
-      /* clamp within parent sequence strip bounds */
+      /* Clamp within parent sequence strip bounds. */
       if (x1_chan < x1) {
         x1_chan = x1;
       }
@@ -453,16 +443,16 @@ static void drawmeta_contents(Scene *scene, Sequence *seqm, float x1, float y1,
   GPU_blend(false);
 }
 
-/* clamp handles to defined size in pixel space */
+/* Get handle width in pixels. */
 float sequence_handle_size_get_clamped(Sequence *seq, const float pixelx)
 {
   const float maxhandle = (pixelx * SEQ_HANDLE_SIZE) * U.pixelsize;
 
-  /* ensure we're not greater than half width */
+  /* Ensure that handle is not wider, than half of strip. */
   return min_ff(maxhandle, ((float)(seq->enddisp - seq->startdisp) / 2.0f) / pixelx);
 }
 
-/* draw a handle, for each end of a sequence strip */
+/* Draw a handle, on left or right side of strip. */
 static void draw_seq_handle(View2D *v2d,
                             Sequence *seq,
                             const float handsize_clamped,
@@ -483,7 +473,7 @@ static void draw_seq_handle(View2D *v2d,
   y1 = seq->machine + SEQ_STRIP_OFSBOTTOM;
   y2 = seq->machine + SEQ_STRIP_OFSTOP;
 
-  /* set up co-ordinates/dimensions for either left or right handle */
+  /* Set up co-ordinates and dimensions for either left or right handle. */
   if (direction == SEQ_LEFTHANDLE) {
     rx1 = x1;
     rx2 = x1 + handsize_clamped;
@@ -495,7 +485,6 @@ static void draw_seq_handle(View2D *v2d,
     whichsel = SEQ_RIGHTSEL;
   }
 
-  /* draw! */
   if (!(seq->type & SEQ_TYPE_EFFECT) || BKE_sequence_effect_get_num_inputs(seq->type) == 0) {
     GPU_blend(true);
 
@@ -522,9 +511,7 @@ static void draw_seq_handle(View2D *v2d,
     GPU_blend(false);
   }
 
-  /* Draw numbers for start and end of the strip next to its handles.
-   *  - Draw only when handles are selected or while translating the strip.
-   */
+  /* Draw numbers for start and end of the strip next to its handles. */
   if (y_threshold &&
       (((seq->flag & SELECT) && (G.moving & G_TRANSFORM_SEQ)) || (seq->flag & whichsel))) {
 
@@ -575,8 +562,8 @@ static void draw_seq_outline(Sequence *seq,
   else if (seq->flag & SELECT) {
     UI_GetThemeColor3ubv(TH_SEQ_SELECTED, col);
   }
-  /* Regular color for unselected strips: a bit darker than the background. */
   else {
+    /* Color for unselected strips is a bit darker than the background. */
     UI_GetThemeColor3ubv(TH_BACK, col);
     UI_GetColorPtrShade3ubv(col, col, -40);
   }
@@ -610,13 +597,13 @@ static void draw_seq_outline(Sequence *seq,
     /* Top */
     immRectf(pos, x1 - pixelx, y2 - 2 * pixely, x2 + pixelx, y2);
   }
-  /* 1px wide outline for unselected strips. */
   else {
+    /* 1px wide outline for unselected strips. */
     imm_draw_box_wire_2d(pos, x1, y1, x2, y2);
   }
 }
 
-/* draw info text on a sequence strip */
+/* Draw info text on a sequence strip. */
 static void draw_seq_text(View2D *v2d,
                           Sequence *seq,
                           SpaceSeq *sseq,
@@ -633,7 +620,7 @@ static void draw_seq_text(View2D *v2d,
   const char *name = seq->name + 2;
   uchar col[4];
 
-  /* note, all strings should include 'name' */
+  /* All strings should include name. */
   if (name[0] == '\0') {
     name = BKE_sequence_give_name(seq);
   }
@@ -723,7 +710,7 @@ static void draw_seq_text(View2D *v2d,
                            seq->len);
   }
   else {
-    /* should never get here!, but might with files from future */
+    /* Should never get here!, but might with files from future. */
     BLI_assert(0);
 
     str_len = BLI_snprintf(str, sizeof(str), "%s | %d", name, seq->len);
@@ -888,7 +875,7 @@ static void draw_seq_background(Scene *scene,
     }
   }
 
-  /* Transition strips.. Draw right half. */
+  /* Draw right half of transition strips. */
   if (ELEM(seq->type, SEQ_TYPE_CROSS, SEQ_TYPE_GAMCROSS, SEQ_TYPE_WIPE)) {
     float vert_pos[3][2];
     Sequence *seq1 = seq->seq1;
@@ -966,7 +953,7 @@ static void calculate_seq_text_offsets(
 
   float scroller_vert_xoffs = (V2D_SCROLL_HANDLE_WIDTH + SEQ_SCROLLER_TEXT_OFFSET) * pixelx;
 
-  /* info text on the strip */
+  /* Info text on the strip. */
   if (*x1 < v2d->cur.xmin + scroller_vert_xoffs) {
     *x1 = v2d->cur.xmin + scroller_vert_xoffs;
   }
@@ -981,11 +968,7 @@ static void calculate_seq_text_offsets(
   }
 }
 
-/*
- * Draw a sequence strip, bounds check already made
- * ARegion is currently only used to get the windows width in pixels
- * so wave file sample drawing precision is zoom adjusted
- */
+/* Draw visible strips. */
 static void draw_seq_strip(const bContext *C,
                            SpaceSeq *sseq,
                            Scene *scene,
@@ -999,20 +982,19 @@ static void draw_seq_strip(const bContext *C,
   const float handsize_clamped = sequence_handle_size_get_clamped(seq, pixelx);
   float pixely = BLI_rctf_size_y(&v2d->cur) / BLI_rcti_size_y(&v2d->mask);
 
-  /* We need to know if this is a single image/color or not for drawing. */
+  /* Check if we are doing "solo preview". */
   bool is_single_image = (char)BKE_sequence_single_check(seq);
 
-  /* body */
+  /* Draw strip body. */
   x1 = (seq->startstill) ? seq->start : seq->startdisp;
   y1 = seq->machine + SEQ_STRIP_OFSBOTTOM;
   x2 = (seq->endstill) ? (seq->start + seq->len) : seq->enddisp;
   y2 = seq->machine + SEQ_STRIP_OFSTOP;
 
-  /* Position of the text,
-   * make sure that the strip content is visible also when the strip height gets lower. */
+  /* Calculate height needed for drawing text on strip. */
   float text_margin_y = y2 - min_ff(0.40f, 20 * U.dpi_fac * pixely);
 
-  /* Show some content only when the strip is high enough. */
+  /* Is there enough space for drawing something else than text? */
   bool y_threshold = ((y2 - y1) / pixely) > 20 * U.dpi_fac;
 
   uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
@@ -1020,12 +1002,12 @@ static void draw_seq_strip(const bContext *C,
 
   draw_seq_background(scene, seq, pos, x1, x2, y1, y2, is_single_image);
 
-  /* Color strips.. Draw a band with the strip's color on its lower part. */
+  /* Draw a color band inside color strip. */
   if (seq->type == SEQ_TYPE_COLOR && y_threshold) {
     draw_color_strip_band(seq, pos, text_margin_y, y1);
   }
 
-  /* Draw strip's offsets when flag is enabled or during "solo preview". */
+  /* Draw strip offsets when flag is enabled or during "solo preview". */
   if (!is_single_image && (seq->startofs || seq->endofs) && pixely > 0) {
     if ((sseq->draw_flag & SEQ_DRAW_OFFSET_EXT) || (seq == special_seq_update)) {
       draw_sequence_extensions(scene, seq, pos, pixely);
@@ -1042,7 +1024,7 @@ static void draw_seq_strip(const bContext *C,
     drawmeta_contents(scene, seq, x1, y1, x2, y2);
   }
 
-  /* Sound strips.. Draw waveforms. */
+  /* Draw sound strip waveform. */
   if ((seq->type == SEQ_TYPE_SOUND_RAM) && (sseq->flag & SEQ_NO_WAVEFORMS) == 0) {
     draw_seq_waveform(v2d,
                       C,
@@ -1061,7 +1043,7 @@ static void draw_seq_strip(const bContext *C,
     draw_seq_locked(x1, y1, x2, y2);
   }
 
-  /* Missing media indication.. Draw a red line on the top of the strip. */
+  /* Draw Red line on the top of invalid strip (Missing media). */
   if (!BKE_sequence_is_valid_check(seq)) {
     draw_seq_invalid(x1, x2, y2, text_margin_y);
   }
@@ -1082,11 +1064,9 @@ static void draw_seq_strip(const bContext *C,
 
   calculate_seq_text_offsets(v2d, seq, &x1, &x2, pixelx);
 
-  /* Draw the text on the top section of the strip,
-   *  - depending on the vertical space, move it to the center or don't draw it.
-   *  - don't draw it when there is not enough horizontal space.
-   */
+  /* Don't draw strip if there is not enough vertical or horizontal space. */
   if (((x2 - x1) > 32 * pixelx * U.dpi_fac) && ((y2 - y1) > 8 * pixely * U.dpi_fac)) {
+    /* Depending on the vertical space, draw text on top or in the center of strip. */
     draw_seq_text(
         v2d, seq, sseq, x1, x2, y_threshold ? text_margin_y : y1, y2, seq_active, y_threshold);
   }
@@ -1203,7 +1183,7 @@ ImBuf *sequencer_ibuf_get(struct Main *bmain,
     GPU_framebuffer_bind(fb);
   }
 
-  /* restore state so real rendering would be canceled (if needed) */
+  /* Restore state so real rendering would be canceled if needed. */
   G.is_break = is_break;
 
   return ibuf;
@@ -1264,17 +1244,17 @@ static void sequencer_display_size(Scene *scene, float r_viewrect[2])
 
 static void sequencer_draw_gpencil(const bContext *C)
 {
-  /* draw grease-pencil (image aligned) */
+  /* Draw grease-pencil (image aligned). */
   ED_annotation_draw_2dimage(C);
 
-  /* ortho at pixel level */
+  /* Ortho at pixel level. */
   UI_view2d_view_restore(C);
 
-  /* draw grease-pencil (screen aligned) */
+  /* Draw grease-pencil (screen aligned). */
   ED_annotation_draw_view2d(C, 0);
 }
 
-/* draws content borders plus safety borders if needed */
+/* Draw content and safety borders borders. */
 static void sequencer_draw_borders(const SpaceSeq *sseq, const View2D *v2d, const Scene *scene)
 {
   float x1 = v2d->tot.xmin;
@@ -1284,7 +1264,7 @@ static void sequencer_draw_borders(const SpaceSeq *sseq, const View2D *v2d, cons
 
   GPU_line_width(1.0f);
 
-  /* border */
+  /* Draw border. */
   const uint shdr_pos = GPU_vertformat_attr_add(
       immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
 
@@ -1301,7 +1281,7 @@ static void sequencer_draw_borders(const SpaceSeq *sseq, const View2D *v2d, cons
 
   imm_draw_box_wire_2d(shdr_pos, x1 - 0.5f, y1 - 0.5f, x2 + 0.5f, y2 + 0.5f);
 
-  /* safety border */
+  /* Draw safety border. */
   if (sseq->flag & SEQ_SHOW_SAFE_MARGINS) {
     immUniformThemeColorBlend(TH_VIEW_OVERLAY, TH_BACK, 0.25f);
 
@@ -1325,8 +1305,8 @@ static void sequencer_draw_borders(const SpaceSeq *sseq, const View2D *v2d, cons
 #if 0
 void sequencer_draw_maskedit(const bContext *C, Scene *scene, ARegion *region, SpaceSeq *sseq)
 {
-  /* NOTE: sequencer mask editing isnt finished, the draw code is working but editing not,
-   * for now just disable drawing since the strip frame will likely be offset */
+  /* NOTE: sequencer mask editing isnt finished, the draw code is working but editing not.
+   * For now just disable drawing since the strip frame will likely be offset. */
 
   // if (sc->mode == SC_MODE_MASKEDIT)
   if (0 && sseq->mainb == SEQ_DRAW_IMG_IMBUF) {
@@ -1377,8 +1357,8 @@ static void *sequencer_OCIO_transform_ibuf(
   force_fallback |= (ED_draw_imbuf_method(ibuf) != IMAGE_DRAW_METHOD_GLSL);
   force_fallback |= (ibuf->dither != 0.0f);
 
+  /* Fallback to CPU based color space conversion. */
   if (force_fallback) {
-    /* Fallback to CPU based color space conversion */
     *r_glsl_used = false;
     *r_format = GL_RGBA;
     *r_type = GL_UNSIGNED_BYTE;
@@ -1423,9 +1403,8 @@ static void *sequencer_OCIO_transform_ibuf(
     display_buffer = NULL;
   }
 
-  /* there's a data to be displayed, but GLSL is not initialized
-   * properly, in this case we fallback to CPU-based display transform
-   */
+  /* There is data to be displayed, but GLSL is not initialized
+   * properly, in this case we fallback to CPU-based display transform. */
   if ((ibuf->rect || ibuf->rect_float) && !*r_glsl_used) {
     display_buffer = IMB_display_buffer_acquire_ctx(C, ibuf, &cache_handle);
     *r_format = GL_RGBA;
@@ -1441,14 +1420,12 @@ static void *sequencer_OCIO_transform_ibuf(
 static void sequencer_stop_running_jobs(const bContext *C, Scene *scene)
 {
   if (G.is_rendering == false && (scene->r.seq_prev_type) == OB_RENDER) {
-    /* stop all running jobs, except screen one. currently previews frustrate Render
-     * needed to make so sequencer's rendering doesn't conflict with compositor
-     */
+    /* Stop all running jobs, except screen one. Currently previews frustrate Render.
+     * Need to make so sequencer's rendering doesn't conflict with compositor. */
     WM_jobs_kill_type(CTX_wm_manager(C), NULL, WM_JOB_TYPE_COMPOSITE);
 
-    /* in case of final rendering used for preview, kill all previews,
-     * otherwise threading conflict will happen in rendering module
-     */
+    /* In case of final rendering used for preview, kill all previews,
+     * otherwise threading conflict will happen in rendering module. */
     WM_jobs_kill_type(CTX_wm_manager(C), NULL, WM_JOB_TYPE_RENDER_PREVIEW);
   }
 }
@@ -1521,8 +1498,7 @@ static void sequencer_draw_display_buffer(const bContext *C,
   }
 
   /* Format needs to be created prior to any immBindProgram call.
-   * Do it here because OCIO binds it's own shader.
-   */
+   * Do it here because OCIO binds it's own shader. */
   int format, type;
   bool glsl_used = false;
   GLuint texid;
@@ -1671,7 +1647,7 @@ static ImBuf *sequencer_get_scope(Scene *scene, SpaceSeq *sseq, ImBuf *ibuf, boo
         break;
     }
 
-    /* future files may have new scopes we don't catch above */
+    /* Future files may have new scopes we don't catch above. */
     if (scope) {
       scopes->reference_ibuf = ibuf;
     }
@@ -1708,13 +1684,13 @@ void sequencer_draw_preview(const bContext *C,
     return;
   }
 
-  /* Setup view */
+  /* Setup view. */
   sequencer_display_size(scene, viewrect);
   UI_view2d_totRect_set(v2d, viewrect[0] + 0.5f, viewrect[1] + 0.5f);
   UI_view2d_curRect_validate(v2d);
   UI_view2d_view_ortho(v2d);
 
-  /* Draw background */
+  /* Draw background. */
   if (!draw_backdrop && (!draw_overlay || sseq->overlay_type == SEQ_DRAW_OVERLAY_REFERENCE)) {
     sequencer_preview_clear();
 
@@ -1722,18 +1698,18 @@ void sequencer_draw_preview(const bContext *C,
       imm_draw_box_checker_2d(v2d->tot.xmin, v2d->tot.ymin, v2d->tot.xmax, v2d->tot.ymax);
     }
   }
-  /* Get image */
+  /* Get image. */
   ibuf = sequencer_ibuf_get(
       bmain, depsgraph, scene, sseq, cfra, frame_ofs, names[sseq->multiview_eye]);
 
   if (ibuf) {
     scope = sequencer_get_scope(scene, sseq, ibuf, draw_backdrop);
 
-    /* Draw image */
+    /* Draw image. */
     sequencer_draw_display_buffer(
         C, scene, region, sseq, ibuf, scope, draw_overlay, draw_backdrop);
 
-    /* Draw over image */
+    /* Draw over image. */
     if (sseq->flag & SEQ_SHOW_METADATA) {
       ED_region_image_metadata_draw(0.0, 0.0, ibuf, &v2d->tot, 1.0, 1.0);
     }
@@ -1746,12 +1722,11 @@ void sequencer_draw_preview(const bContext *C,
   if (draw_gpencil && show_imbuf) {
     sequencer_draw_gpencil(C);
   }
+#if 0
+  sequencer_draw_maskedit(C, scene, region, sseq);
+#endif
 
-  /* TODO */
-  /* sequencer_draw_maskedit(C, scene, region, sseq); */
-
-  /* Scope is freed in sequencer_check_scopes when ibuf changes and
-   * scope image is to be replaced. */
+  /* Scope is freed in sequencer_check_scopes when ibuf changes and redraw is needed. */
   if (ibuf) {
     IMB_freeImBuf(ibuf);
   }
@@ -1760,7 +1735,7 @@ void sequencer_draw_preview(const bContext *C,
   seq_prefetch_wm_notify(C, scene);
 }
 
-/* draw backdrop of the sequencer strips view */
+/* Draw backdrop in sequencer timeline. */
 static void draw_seq_backdrop(View2D *v2d)
 {
   int i;
@@ -1768,11 +1743,11 @@ static void draw_seq_backdrop(View2D *v2d)
   uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
   immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
 
-  /* darker gray overlay over the view backdrop */
+  /* Darker gray overlay over the view backdrop. */
   immUniformThemeColorShade(TH_BACK, -20);
   immRectf(pos, v2d->cur.xmin, -1.0, v2d->cur.xmax, 1.0);
 
-  /* Alternating horizontal stripes */
+  /* Alternating horizontal stripes. */
   i = max_ii(1, ((int)v2d->cur.ymin) - 1);
 
   while (i < v2d->cur.ymax) {
@@ -1788,7 +1763,7 @@ static void draw_seq_backdrop(View2D *v2d)
     i++;
   }
 
-  /* Darker lines separating the horizontal bands */
+  /* Darker lines separating the horizontal bands. */
   i = max_ii(1, ((int)v2d->cur.ymin) - 1);
   int line_len = (int)v2d->cur.ymax - i + 1;
   immUniformThemeColor(TH_GRID);
@@ -1802,7 +1777,6 @@ static void draw_seq_backdrop(View2D *v2d)
   immUnbindProgram();
 }
 
-/* draw the contents of the sequencer strips view */
 static void draw_seq_strips(const bContext *C, Editing *ed, ARegion *region)
 {
   Scene *scene = CTX_data_scene(C);
@@ -1812,12 +1786,12 @@ static void draw_seq_strips(const bContext *C, Editing *ed, ARegion *region)
   int sel = 0, j;
   float pixelx = BLI_rctf_size_x(&v2d->cur) / BLI_rcti_size_x(&v2d->mask);
 
-  /* loop through twice, first unselected, then selected */
+  /* Loop through twice, first unselected, then selected. */
   for (j = 0; j < 2; j++) {
     Sequence *seq;
-    /* loop through strips, checking for those that are visible */
+    /* Loop through strips, checking for those that are visible. */
     for (seq = ed->seqbasep->first; seq; seq = seq->next) {
-      /* boundbox and selection tests for NOT drawing the strip... */
+      /* Boundbox and selection tests for NOT drawing the strip. */
       if ((seq->flag & SELECT) != sel) {
         continue;
       }
@@ -1837,11 +1811,11 @@ static void draw_seq_strips(const bContext *C, Editing *ed, ARegion *region)
         continue;
       }
 
-      /* strip passed all tests unscathed... so draw it now */
+      /* Strip passed all tests, draw it now. */
       draw_seq_strip(C, sseq, scene, region, seq, pixelx, seq == last_seq ? true : false);
     }
 
-    /* draw selected next time round */
+    /* Draw selected next time round. */
     sel = SELECT;
   }
 
@@ -1872,7 +1846,7 @@ static void draw_seq_strips(const bContext *C, Editing *ed, ARegion *region)
     }
   }
 
-  /* draw highlight when previewing a single strip */
+  /* Draw highlight if "solo preview" is used. */
   if (special_seq_update) {
     const Sequence *seq = special_seq_update;
     GPU_blend(true);
@@ -1904,8 +1878,7 @@ static void seq_draw_sfra_efra(Scene *scene, View2D *v2d)
   uint pos = GPU_vertformat_attr_add(immVertexFormat(), "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
   immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
 
-  /* draw darkened area outside of active timeline
-   * frame range used is preview range or scene range */
+  /* Draw overlay outside of frame range. */
   immUniformThemeColorShadeAlpha(TH_BACK, -25, -100);
 
   if (frame_sta < frame_end) {
@@ -1918,7 +1891,7 @@ static void seq_draw_sfra_efra(Scene *scene, View2D *v2d)
 
   immUniformThemeColorShade(TH_BACK, -60);
 
-  /* thin lines where the actual frames are */
+  /* Draw frame range boundary. */
   immBegin(GPU_PRIM_LINES, 4);
 
   immVertex2f(pos, frame_sta, v2d->cur.ymin);
@@ -1929,7 +1902,7 @@ static void seq_draw_sfra_efra(Scene *scene, View2D *v2d)
 
   immEnd();
 
-  /* While inside a meta strip, draw a checkerboard pattern outside of its range. */
+  /* While in meta strip, draw a checkerboard overlay outside of frame range. */
   if (ed && !BLI_listbase_is_empty(&ed->metastack)) {
     MetaStack *ms = ed->metastack.last;
     immUnbindProgram();
@@ -1979,7 +1952,7 @@ typedef struct CacheDrawData {
   size_t final_out_vert_count;
 } CacheDrawData;
 
-/* Called as a callback */
+/* Called as a callback. */
 static bool draw_cache_view_init_fn(void *userdata, size_t item_count)
 {
   if (item_count == 0) {
@@ -2175,7 +2148,7 @@ static void draw_cache_view(const bContext *C)
   GPU_blend(false);
 }
 
-/* Draw Timeline/Strip Editor Mode for Sequencer */
+/* Draw sequencer timeline. */
 void draw_timeline_seq(const bContext *C, ARegion *region)
 {
   Scene *scene = CTX_data_scene(C);
@@ -2188,7 +2161,6 @@ void draw_timeline_seq(const bContext *C, ARegion *region)
 
   seq_prefetch_wm_notify(C, scene);
 
-  /* clear and setup matrix */
   UI_GetThemeColor3fv(TH_BACK, col);
   if (ed && ed->metastack.first) {
     GPU_clear_color(col[0], col[1], col[2] - 0.1f, 0.0f);
@@ -2199,44 +2171,36 @@ void draw_timeline_seq(const bContext *C, ARegion *region)
   GPU_clear(GPU_COLOR_BIT);
 
   UI_view2d_view_ortho(v2d);
-
-  /* calculate extents of sequencer strips/data
-   * NOTE: needed for the scrollers later
-   */
+  /* Get timeline boundbox, needed for the scrollers. */
   boundbox_seq(scene, &v2d->tot);
-
-  /* draw backdrop */
   draw_seq_backdrop(v2d);
-
-  /* regular grid-pattern over the rest of the view (i.e. 1-second grid lines) */
   UI_view2d_constant_grid_draw(v2d, FPS);
 
-  /* Only draw backdrop in pure sequence view. */
+  /* Only draw backdrop in timeline view. */
   if (sseq->view == SEQ_VIEW_SEQUENCE && sseq->draw_flag & SEQ_DRAW_BACKDROP) {
     sequencer_draw_preview(C, scene, region, sseq, scene->r.cfra, 0, false, true);
     UI_view2d_view_ortho(v2d);
   }
 
+  /* Draw attached callbacks. */
   ED_region_draw_cb_draw(C, region, REGION_DRAW_PRE_VIEW);
-
   seq_draw_sfra_efra(scene, v2d);
 
-  /* sequence strips (if there is data available to be drawn) */
   if (ed) {
-    /* draw the data */
     draw_seq_strips(C, ed, region);
-    /* text draw cached (for sequence names), in pixelspace now */
+    /* Draw text added in previous function. */
     UI_view2d_text_cache_draw(region);
   }
 
-  /* current frame */
   UI_view2d_view_ortho(v2d);
   if ((sseq->flag & SEQ_DRAWFRAMES) == 0) {
     cfra_flag |= DRAWCFRA_UNIT_SECONDS;
   }
+
+  /* Draw playhead. */
   ANIM_draw_cfra(C, v2d, cfra_flag);
 
-  /* overlap playhead */
+  /* Draw overlap playhead. */
   if (scene->ed && scene->ed->over_flag & SEQ_EDIT_OVERLAY_SHOW) {
     int cfra_over = (scene->ed->over_flag & SEQ_EDIT_OVERLAY_ABS) ?
                         scene->ed->over_cfra :
@@ -2247,7 +2211,8 @@ void draw_timeline_seq(const bContext *C, ARegion *region)
     float viewport_size[4];
     GPU_viewport_size_get_f(viewport_size);
     immUniform2f("viewport_size", viewport_size[2], viewport_size[3]);
-    immUniform1i("colors_len", 0); /* "simple" mode */
+    /* Shader may have color set from past usage - reset it. */
+    immUniform1i("colors_len", 0);
     immUniform1f("dash_width", 20.0f * U.pixelsize);
     immUniform1f("dash_factor", 0.5f);
     immUniformThemeColor(TH_CFRAME);
@@ -2260,7 +2225,6 @@ void draw_timeline_seq(const bContext *C, ARegion *region)
     immUnbindProgram();
   }
 
-  /* markers */
   UI_view2d_view_orthoSpecial(region, v2d, 1);
   int marker_draw_flag = DRAW_MARKERS_MARGIN;
   if (sseq->flag & SEQ_SHOW_MARKERS) {
@@ -2268,28 +2232,22 @@ void draw_timeline_seq(const bContext *C, ARegion *region)
   }
 
   UI_view2d_view_ortho(v2d);
-  /* draw cache on top of markers area */
+
   if (ed) {
     draw_cache_view(C);
   }
-  /* preview range */
+
   ANIM_draw_previewrange(C, v2d, 1);
 
-  /* callback */
+  /* Draw registered callbacks. */
   ED_region_draw_cb_draw(C, region, REGION_DRAW_POST_VIEW);
-
-  /* reset view matrix */
   UI_view2d_view_restore(C);
-
-  /* scrubbing region */
   ED_time_scrub_draw(region, scene, !(sseq->flag & SEQ_DRAWFRAMES), true);
-
-  /* scrollers */
   scrollers = UI_view2d_scrollers_calc(v2d, NULL);
   UI_view2d_scrollers_draw(v2d, scrollers);
   UI_view2d_scrollers_free(scrollers);
 
-  /* channel numbers */
+  /* Draw channel numbers. */
   {
     rcti rect;
     BLI_rcti_init(
diff --git a/source/blender/editors/space_sequencer/sequencer_edit.c b/source/blender/editors/space_sequencer/sequencer_edit.c
index 3d9de1f567c..c2ffb2f55c2 100644
--- a/source/blender/editors/space_sequencer/sequencer_edit.c
+++ b/source/blender/editors/space_sequencer/sequencer_edit.c
@@ -52,7 +52,7 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
-/* for menu/popup icons etc etc*/
+/* For menu, popup, icons, etc. */
 
 #include "ED_anim_api.h"
 #include "ED_numinput.h"
@@ -67,11 +67,11 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
 
-/* own include */
+/* Own include. */
 #include "sequencer_intern.h"
 
 /* XXX */
-/* RNA Enums, used in multiple files */
+/* RNA Enums, used in multiple files. */
 EnumPropertyItem sequencer_prop_effect_types[] = {
     {SEQ_TYPE_CROSS, "CROSS", 0, "Crossfade", "Crossfade effect strip type"},
     {SEQ_TYPE_ADD, "ADD", 0, "Add", "Add effect strip type"},
@@ -94,8 +94,6 @@ EnumPropertyItem sequencer_prop_effect_types[] = {
     {0, NULL, 0, NULL, NULL},
 };
 
-/* mute operator */
-
 #define SEQ_SIDE_MOUSE -1
 
 EnumPropertyItem prop_side_types[] = {
@@ -144,7 +142,7 @@ static void proxy_freejob(void *pjv)
   MEM_freeN(pj);
 }
 
-/* only this runs inside thread */
+/* Only this runs inside thread. */
 static void proxy_startjob(void *pjv, short *stop, short *do_update, float *progress)
 {
   ProxyJob *pj = pjv;
@@ -291,7 +289,7 @@ static int mouse_frame_side(View2D *v2d, short mouse_x, int frame)
   mval[0] = mouse_x;
   mval[1] = 0;
 
-  /* choose the side based on which side of the playhead the mouse is on */
+  /* Choose the side based on which side of the playhead the mouse is on. */
   UI_view2d_region_to_view(v2d, mval[0], mval[1], &mouseloc[0], &mouseloc[1]);
 
   return mouseloc[0] > frame ? SEQ_SIDE_RIGHT : SEQ_SIDE_LEFT;
@@ -299,7 +297,7 @@ static int mouse_frame_side(View2D *v2d, short mouse_x, int frame)
 
 Sequence *find_neighboring_sequence(Scene *scene, Sequence *test, int lr, int sel)
 {
-  /* sel - 0==unselected, 1==selected, -1==done care*/
+  /* sel: 0==unselected, 1==selected, -1==don't care. */
   Sequence *seq;
   Editing *ed = BKE_sequencer_editing_get(scene, false);
 
@@ -334,7 +332,7 @@ Sequence *find_neighboring_sequence(Scene *scene, Sequence *test, int lr, int se
 
 static Sequence *find_next_prev_sequence(Scene *scene, Sequence *test, int lr, int sel)
 {
-  /* sel - 0==unselected, 1==selected, -1==done care*/
+  /* sel: 0==unselected, 1==selected, -1==don't care. */
   Sequence *seq, *best_seq = NULL;
   Editing *ed = BKE_sequencer_editing_get(scene, false);
 
@@ -375,7 +373,7 @@ static Sequence *find_next_prev_sequence(Scene *scene, Sequence *test, int lr, i
     }
     seq = seq->next;
   }
-  return best_seq; /* can be null */
+  return best_seq; /* Can be null. */
 }
 
 Sequence *find_nearest_seq(Scene *scene, View2D *v2d, int *hand, const int mval[2])
@@ -400,22 +398,21 @@ Sequence *find_nearest_seq(Scene *scene, View2D *v2d, int *hand, const int mval[
 
   while (seq) {
     if (seq->machine == (int)y) {
-      /* check for both normal strips, and strips that have been flipped horizontally */
+      /* Check for both normal strips, and strips that have been flipped horizontally. */
       if (((seq->startdisp < seq->enddisp) && (seq->startdisp <= x && seq->enddisp >= x)) ||
           ((seq->startdisp > seq->enddisp) && (seq->startdisp >= x && seq->enddisp <= x))) {
         if (BKE_sequence_tx_test(seq)) {
 
-          /* clamp handles to defined size in pixel space */
-
+          /* Clamp handles to defined size in pixel space. */
           handsize = 2.0f * sequence_handle_size_get_clamped(seq, pixelx);
           displen = (float)abs(seq->startdisp - seq->enddisp);
 
-          /* don't even try to grab the handles of small strips */
+          /* Don't even try to grab the handles of small strips. */
           if (displen / pixelx > 16) {
+
             /* Set the max value to handle to 1/3 of the total len when its
              * less than 28. This is important because otherwise selecting
              * handles happens even when you click in the middle. */
-
             if ((displen / 3) < 30 * pixelx) {
               handsize = displen / 3;
             }
@@ -510,7 +507,6 @@ void recurs_sel_seq(Sequence *seqm)
 
 bool ED_space_sequencer_maskedit_mask_poll(bContext *C)
 {
-  /* in this case both funcs are the same, for clip editor not */
   return ED_space_sequencer_maskedit_poll(C);
 }
 
@@ -535,7 +531,7 @@ bool ED_space_sequencer_maskedit_poll(bContext *C)
   return false;
 }
 
-/* are we displaying the seq output (not channels or histogram)*/
+/* Are we displaying the seq output (not channels or histogram). */
 bool ED_space_sequencer_check_show_imbuf(SpaceSeq *sseq)
 {
   return (ELEM(sseq->view, SEQ_VIEW_PREVIEW, SEQ_VIEW_SEQUENCE_PREVIEW) &&
@@ -589,8 +585,8 @@ int seq_effect_find_selected(Scene *scene,
     }
   }
 
-  /* make sequence selection a little bit more intuitive
-   * for 3 strips: the last-strip should be sequence3 */
+  /* Make sequence selection a little bit more intuitive
+   * for 3 strips: the last-strip should be seq3. */
   if (seq3 != NULL && seq2 != NULL) {
     Sequence *tmp = seq2;
     seq2 = seq3;
@@ -600,7 +596,7 @@ int seq_effect_find_selected(Scene *scene,
   switch (BKE_sequence_effect_get_num_inputs(type)) {
     case 0:
       *r_selseq1 = *r_selseq2 = *r_selseq3 = NULL;
-      return 1; /* success */
+      return 1; /* Success. */
     case 1:
       if (seq2 == NULL) {
         *r_error_str = N_("At least one selected sequence strip is needed");
@@ -640,8 +636,8 @@ static Sequence *del_seq_find_replace_recurs(Scene *scene, Sequence *seq)
 {
   Sequence *seq1, *seq2, *seq3;
 
-  /* try to find a replacement input sequence, and flag for later deletion if
-   * no replacement can be found */
+  /* Try to find a replacement input sequence, and flag for later deletion if
+   * no replacement can be found. */
 
   if (!seq) {
     return NULL;
@@ -650,13 +646,13 @@ static Sequence *del_seq_find_replace_recurs(Scene *scene, Sequence *seq)
     return ((seq->flag & SELECT) ? NULL : seq);
   }
   else if (!(seq->flag & SELECT)) {
-    /* try to find replacement for effect inputs */
+    /* Try to find replacement for effect inputs. */
     seq1 = del_seq_find_replace_recurs(scene, seq->seq1);
     seq2 = del_seq_find_replace_recurs(scene, seq->seq2);
     seq3 = del_seq_find_replace_recurs(scene, seq->seq3);
 
     if (seq1 == seq->seq1 && seq2 == seq->seq2 && seq3 == seq->seq3) {
-      /* pass */
+      /* Pass. */
     }
     else if (seq1 || seq2 || seq3) {
       seq->seq1 = (seq1) ? seq1 : (seq2) ? seq2 : seq3;
@@ -666,7 +662,7 @@ static Sequence *del_seq_find_replace_recurs(Scene *scene, Sequence *seq)
       BKE_sequencer_update_changed_seq_and_deps(scene, seq, 1, 1);
     }
     else {
-      seq->flag |= SELECT; /* mark for delete */
+      seq->flag |= SELECT; /* Mark for delete. */
     }
   }
 
@@ -740,7 +736,7 @@ static Sequence *split_seq_hard(
   /* Unlike soft-split, it's important to use the same value for both strips. */
   const bool is_end_exact = ((seq->start + seq->len) == split_frame);
 
-  /* backup values */
+  /* Backup values. */
   ts.start = seq->start;
   ts.machine = seq->machine;
   ts.startstill = seq->startstill;
@@ -753,21 +749,19 @@ static Sequence *split_seq_hard(
   ts.anim_endofs = seq->anim_endofs;
   ts.len = seq->len;
 
-  /* First Strip! */
-  /* strips with extended stillfames before */
-
-  /* Precaution, needed because the length saved on-disk may not match the length saved in the
-   * blend file, or our code may have minor differences reading file length between versions.
-   * This causes hard-split to fail, see: T47862 */
   if (seq->type != SEQ_TYPE_META) {
+    /* Precaution, needed because the length saved on-disk may not match the length saved in the
+     * blend file, or our code may have minor differences reading file length between versions.
+     * This causes hard-split to fail, see: T47862. */
     BKE_sequence_reload_new_file(bmain, scene, seq, true);
     BKE_sequence_calc(scene, seq);
   }
 
+  /* First Strip. */
   /* Important to offset the start when 'split_frame == seq->start'
    * because we need at least one frame of content after start/end still have clipped it. */
   if ((seq->startstill) && (split_frame <= seq->start)) {
-    /* don't do funny things with METAs ... */
+    /* Don't do funny things with METAs. */
     if (seq->type == SEQ_TYPE_META) {
       skip_dup = true;
       seq->startstill = seq->start - split_frame;
@@ -779,18 +773,18 @@ static Sequence *split_seq_hard(
       seq->endstill = 0;
     }
   }
-  /* normal strip */
+  /* Normal strip. */
   else if ((is_end_exact == false) &&
            ((split_frame >= seq->start) && (split_frame <= (seq->start + seq->len)))) {
     seq->endofs = 0;
     seq->endstill = 0;
     seq->anim_endofs += (seq->start + seq->len) - split_frame;
   }
-  /* strips with extended stillframes after */
+  /* Strips with extended stillframes. */
   else if ((is_end_exact == true) ||
            (((seq->start + seq->len) < split_frame) && (seq->endstill))) {
     seq->endstill -= seq->enddisp - split_frame;
-    /* don't do funny things with METAs ... */
+    /* Don't do funny things with METAs. */
     if (seq->type == SEQ_TYPE_META) {
       skip_dup = true;
     }
@@ -800,7 +794,7 @@ static Sequence *split_seq_hard(
   BKE_sequence_calc(scene, seq);
 
   if (!skip_dup) {
-    /* Duplicate AFTER the first change */
+    /* Duplicate AFTER the first change. */
     seqn = BKE_sequence_dupli_recursive(
         scene, scene, new_seq_list, seq, SEQ_DUPE_UNIQUE_NAME | SEQ_DUPE_ANIM);
   }
@@ -808,12 +802,11 @@ static Sequence *split_seq_hard(
   if (seqn) {
     seqn->flag |= SELECT;
 
-    /* Important not to re-assign this (unlike soft-split) */
 #if 0
     is_end_exact = ((seqn->start + seqn->len) == split_frame);
 #endif
-    /* Second Strip! */
-    /* strips with extended stillframes before */
+    /* Second Strip. */
+    /* strips with extended stillframes. */
     if ((seqn->startstill) && (split_frame == seqn->start + 1)) {
       seqn->start = ts.start;
       seqn->startstill = ts.start - split_frame;
@@ -821,7 +814,7 @@ static Sequence *split_seq_hard(
       seqn->endstill = ts.endstill;
     }
 
-    /* normal strip */
+    /* Normal strip. */
     else if ((is_end_exact == false) &&
              ((split_frame >= seqn->start) && (split_frame <= (seqn->start + seqn->len)))) {
       seqn->start = split_frame;
@@ -833,7 +826,7 @@ static Sequence *split_seq_hard(
       seqn->endstill = ts.endstill;
     }
 
-    /* strips with extended stillframes after */
+    /* Strips with extended stillframes after. */
     else if ((is_end_exact == true) ||
              (((seqn->start + seqn->len) < split_frame) && (seqn->endstill))) {
       seqn->start = split_frame;
@@ -858,7 +851,7 @@ static Sequence *split_seq_soft(
 
   bool is_end_exact = ((seq->start + seq->len) == split_frame);
 
-  /* backup values */
+  /* Backup values. */
   ts.start = seq->start;
   ts.machine = seq->machine;
   ts.startstill = seq->startstill;
@@ -871,9 +864,8 @@ static Sequence *split_seq_soft(
   ts.anim_endofs = seq->anim_endofs;
   ts.len = seq->len;
 
-  /* First Strip! */
-  /* strips with extended stillfames before */
-
+  /* First Strip. */
+  /* Strips with extended stillfames. */
   /* Important to offset the start when 'split_frame == seq->start'
    * because we need at least one frame of content after start/end still have clipped it. */
   if ((seq->startstill) && (split_frame <= seq->start)) {
@@ -889,16 +881,16 @@ static Sequence *split_seq_soft(
       seq->endstill = 0;
     }
   }
-  /* normal strip */
+  /* Normal strip. */
   else if ((is_end_exact == false) && (split_frame >= seq->start) &&
            (split_frame <= (seq->start + seq->len))) {
     seq->endofs = (seq->start + seq->len) - split_frame;
   }
-  /* strips with extended stillframes after */
+  /* Strips with extended stillframes. */
   else if ((is_end_exact == true) ||
            (((seq->start + seq->len) < split_frame) && (seq->endstill))) {
     seq->endstill -= seq->enddisp - split_frame;
-    /* don't do funny things with METAs ... */
+    /* Don't do funny things with METAs. */
     if (seq->type == SEQ_TYPE_META) {
       skip_dup = true;
     }
@@ -907,7 +899,7 @@ static Sequence *split_seq_soft(
   BKE_sequence_calc(scene, seq);
 
   if (!skip_dup) {
-    /* Duplicate AFTER the first change */
+    /* Duplicate AFTER the first change. */
     seqn = BKE_sequence_dupli_recursive(
         scene, scene, new_seq_list, seq, SEQ_DUPE_UNIQUE_NAME | SEQ_DUPE_ANIM);
   }
@@ -917,8 +909,8 @@ static Sequence *split_seq_soft(
 
     is_end_exact = ((seqn->start + seqn->len) == split_frame);
 
-    /* Second Strip! */
-    /* strips with extended stillframes before */
+    /* Second Strip. */
+    /* Strips with extended stillframes. */
     if ((seqn->startstill) && (split_frame == seqn->start + 1)) {
       seqn->start = ts.start;
       seqn->startstill = ts.start - split_frame;
@@ -926,7 +918,7 @@ static Sequence *split_seq_soft(
       seqn->endstill = ts.endstill;
     }
 
-    /* normal strip */
+    /* Normal strip. */
     else if ((is_end_exact == false) && (split_frame >= seqn->start) &&
              (split_frame <= (seqn->start + seqn->len))) {
       seqn->startstill = 0;
@@ -935,7 +927,7 @@ static Sequence *split_seq_soft(
       seqn->endstill = ts.endstill;
     }
 
-    /* strips with extended stillframes after */
+    /* Strips with extended stillframes. */
     else if ((is_end_exact == true) ||
              (((seqn->start + seqn->len) < split_frame) && (seqn->endstill))) {
       seqn->start = split_frame - ts.len + 1;
@@ -949,12 +941,12 @@ static Sequence *split_seq_soft(
   return seqn;
 }
 
-/* like duplicate, but only duplicate and split overlapping strips,
+/* Like duplicate, but only duplicate and split overlapping strips,
  * strips to the left of the split_frame are ignored and strips to the right
- * are moved to the end of slist
- * we have to work on the same slist (not using a separate list), since
+ * are moved to the end of slist.
+ * We have to work on the same slist (not using a separate list), since
  * otherwise dupli_seq can't check for duplicate names properly and
- * may generate strips with the same name (which will mess up animdata)
+ * may generate strips with the same name which will mess up animdata.
  */
 
 static bool split_seq_list(
@@ -973,7 +965,7 @@ static bool split_seq_list(
   seq = slist->first;
 
   while (seq && seq != seq_first_new) {
-    seq_next_iter = seq->next; /* we need this because we may remove seq */
+    seq_next_iter = seq->next; /* We need this because we may remove seq. */
     seq->tmp = NULL;
     if (use_cursor_position) {
       if (seq->machine == channel && seq->startdisp < split_frame && seq->enddisp > split_frame) {
@@ -996,10 +988,10 @@ static bool split_seq_list(
           }
         }
         else if (seq->enddisp <= split_frame) {
-          /* do nothing */
+          /* Pass. */
         }
         else if (seq->startdisp >= split_frame) {
-          /* move to tail */
+          /* Move to tail. */
           BLI_remlink(slist, seq);
           BLI_addtail(slist, seq);
 
@@ -1022,7 +1014,7 @@ static bool sequence_offset_after_frame(Scene *scene, const int delta, const int
   bool done = false;
   TimeMarker *marker;
 
-  /* all strips >= cfra are shifted */
+  /* All strips >= cfra are shifted. */
 
   if (ed == NULL) {
     return 0;
@@ -1085,12 +1077,12 @@ static void UNUSED_FUNCTION(seq_remap_paths)(Scene *scene)
   }
 
   BLI_strncpy(from, last_seq->strip->dir, sizeof(from));
-  // XXX  if (0 == sbutton(from, 0, sizeof(from) - 1, "From: "))
-  //      return;
+  /* XXX  if (0 == sbutton(from, 0, sizeof(from) - 1, "From: "))
+   *      return; */
 
   BLI_strncpy(to, from, sizeof(to));
-  // XXX  if (0 == sbutton(to, 0, sizeof(to) - 1, "To: "))
-  //      return;
+  /* XXX  if (0 == sbutton(to, 0, sizeof(to) - 1, "To: "))
+   *      return; */
 
   if (STREQ(to, from)) {
     return;
@@ -1101,11 +1093,11 @@ static void UNUSED_FUNCTION(seq_remap_paths)(Scene *scene)
       if (STREQLEN(seq->strip->dir, from, strlen(from))) {
         printf("found %s\n", seq->strip->dir);
 
-        /* strip off the beginning */
+        /* Strip off the beginning. */
         stripped[0] = 0;
         BLI_strncpy(stripped, seq->strip->dir + strlen(from), FILE_MAX);
 
-        /* new path */
+        /* New path. */
         BLI_snprintf(seq->strip->dir, sizeof(seq->strip->dir), "%s%s", to, stripped);
         printf("new %s\n", seq->strip->dir);
       }
@@ -1122,12 +1114,12 @@ static int sequencer_gap_remove_exec(bContext *C, wmOperator *op)
   bool first = false, done;
   bool do_all = RNA_boolean_get(op->ptr, "all");
 
-  /* get first and last frame */
+  /* Get first and last frame. */
   boundbox_seq(scene, &rectf);
   sfra = (int)rectf.xmin;
   efra = (int)rectf.xmax;
 
-  /* first check if the current frame has a gap already */
+  /* Check if the current frame has a gap already. */
   for (cfra = CFRA; cfra >= sfra; cfra--) {
     if (BKE_sequencer_evaluate_frame(scene, cfra)) {
       first = true;
@@ -1136,7 +1128,7 @@ static int sequencer_gap_remove_exec(bContext *C, wmOperator *op)
   }
 
   for (; cfra < efra; cfra++) {
-    /* first == 0 means there's still no strip to remove a gap for */
+    /* There's still no strip to remove a gap for. */
     if (first == false) {
       if (BKE_sequencer_evaluate_frame(scene, cfra)) {
         first = true;
@@ -1164,19 +1156,19 @@ static int sequencer_gap_remove_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_gap_remove(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Remove Gaps";
   ot->idname = "SEQUENCER_OT_gap_remove";
   ot->description =
       "Remove gap at current frame to first strip at the right, independent of selection or "
       "locked state of strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   //  ot->invoke = sequencer_snap_invoke;
   ot->exec = sequencer_gap_remove_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   RNA_def_boolean(ot->srna, "all", 0, "All Gaps", "Do all gaps to right of current frame");
@@ -1196,19 +1188,19 @@ static int sequencer_gap_insert_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_gap_insert(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Insert Gaps";
   ot->idname = "SEQUENCER_OT_gap_insert";
   ot->description =
       "Insert gap at current frame to first strips at the right, independent of selection or "
       "locked state of strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   //  ot->invoke = sequencer_snap_invoke;
   ot->exec = sequencer_gap_insert_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   RNA_def_int(ot->srna,
@@ -1238,7 +1230,7 @@ static int seq_get_snaplimit(View2D *v2d)
 }
 #endif
 
-/* Operator functions */
+/* Operator functions. */
 bool sequencer_edit_poll(bContext *C)
 {
   return (BKE_sequencer_editing_get(CTX_data_scene(C), false) != NULL);
@@ -1282,7 +1274,7 @@ bool sequencer_view_strips_poll(bContext *C)
   return 0;
 }
 
-/* snap operator*/
+/* Snap operator. */
 static int sequencer_snap_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -1293,14 +1285,11 @@ static int sequencer_snap_exec(bContext *C, wmOperator *op)
 
   snap_frame = RNA_int_get(op->ptr, "frame");
 
-  /* also check metas */
+  /* Check metas. */
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if (seq->flag & SELECT && !(seq->depth == 0 && seq->flag & SEQ_LOCK) &&
         BKE_sequence_tx_test(seq)) {
       if ((seq->flag & (SEQ_LEFTSEL + SEQ_RIGHTSEL)) == 0) {
-        /* simple but no anim update */
-        /* seq->start = snap_frame-seq->startofs+seq->startstill; */
-
         BKE_sequence_translate(
             scene, seq, (snap_frame - seq->startofs + seq->startstill) - seq->start);
       }
@@ -1318,8 +1307,8 @@ static int sequencer_snap_exec(bContext *C, wmOperator *op)
     }
   }
 
-  /* test for effects and overlap
-   * don't use SEQP_BEGIN since that would be recursive */
+  /* Test for effects and overlap.
+   * Don't use SEQP_BEGIN since that would be recursive. */
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if (seq->flag & SELECT && !(seq->depth == 0 && seq->flag & SEQ_LOCK)) {
       seq->flag &= ~SEQ_OVERLAP;
@@ -1340,7 +1329,6 @@ static int sequencer_snap_exec(bContext *C, wmOperator *op)
     }
   }
 
-  /* as last: */
   BKE_sequencer_sort(scene);
 
   DEG_id_tag_update(&scene->id, ID_RECALC_SEQUENCER_STRIPS);
@@ -1363,17 +1351,17 @@ static int sequencer_snap_invoke(bContext *C, wmOperator *op, const wmEvent *UNU
 
 void SEQUENCER_OT_snap(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Snap Strips to Playhead";
   ot->idname = "SEQUENCER_OT_snap";
   ot->description = "Frame where selected strips will be snapped";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_snap_invoke;
   ot->exec = sequencer_snap_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   RNA_def_int(ot->srna,
@@ -1395,7 +1383,7 @@ typedef struct SlipData {
   bool *trim;
   int num_seq;
   bool slow;
-  int slow_offset; /* offset at the point where offset was turned on */
+  int slow_offset; /* Offset at the point where offset was turned on. */
   NumInput num_input;
 } SlipData;
 
@@ -1442,7 +1430,7 @@ static int slip_add_sequences_recursive(
       num_items++;
 
       if (seq->type == SEQ_TYPE_META) {
-        /* trim the sub-sequences */
+        /* Trim the sub-sequences. */
         num_items += slip_add_sequences_recursive(
             &seq->seqbase, seq_array, trim, num_items + offset, false);
       }
@@ -1465,7 +1453,7 @@ static int slip_count_sequences_recursive(ListBase *seqbasep, bool first_level)
       trimmed_sequences++;
 
       if (seq->type == SEQ_TYPE_META) {
-        /* trim the sub-sequences */
+        /* Trim the sub-sequences. */
         trimmed_sequences += slip_count_sequences_recursive(&seq->seqbase, false);
       }
     }
@@ -1483,7 +1471,7 @@ static int sequencer_slip_invoke(bContext *C, wmOperator *op, const wmEvent *eve
   int num_seq, i;
   View2D *v2d = UI_view2d_fromcontext(C);
 
-  /* first recursively count the trimmed elements */
+  /* Recursively count the trimmed elements. */
   num_seq = slip_count_sequences_recursive(ed->seqbasep, true);
 
   if (num_seq == 0) {
@@ -1517,7 +1505,7 @@ static int sequencer_slip_invoke(bContext *C, wmOperator *op, const wmEvent *eve
 
   WM_event_add_modal_handler(C, op);
 
-  /* notify so we draw extensions immediately */
+  /* Notify so we draw extensions immediately. */
   WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, scene);
 
   return OPERATOR_RUNNING_MODAL;
@@ -1529,20 +1517,19 @@ static bool sequencer_slip_recursively(Scene *scene, SlipData *data, int offset)
   Editing *ed = BKE_sequencer_editing_get(scene, false);
   bool changed = false;
 
-  /* We iterate in reverse so meta-strips are iterated after their children. */
+  /* Iterate in reverse so meta-strips are iterated after their children. */
   for (int i = data->num_seq - 1; i >= 0; i--) {
     Sequence *seq = data->seq_array[i];
     int endframe;
-    /* We have the offset, apply the values to the sequence strips. */
 
-    /* first, do the offset */
+    /* Offset seq start. */
     seq->start = data->ts[i].start + offset;
 
     if (data->trim[i]) {
       /* Find the end-frame. */
       endframe = seq->start + seq->len;
 
-      /* Now compute the sequence offsets. */
+      /* Compute the sequence offsets. */
       if (endframe > seq->enddisp) {
         seq->endstill = 0;
         seq->endofs = endframe - seq->enddisp;
@@ -1566,7 +1553,7 @@ static bool sequencer_slip_recursively(Scene *scene, SlipData *data, int offset)
       }
     }
     else {
-      /* If no real trim, don't change the data, rather transform the strips themselves. */
+      /* No transform data (likely effect strip). Only move start and end. */
       seq->startdisp = data->ts[i].startdisp + offset;
       seq->enddisp = data->ts[i].enddisp + offset;
       changed = true;
@@ -1575,7 +1562,7 @@ static bool sequencer_slip_recursively(Scene *scene, SlipData *data, int offset)
     /* Effects are only added if we they are in a meta-strip.
      * In this case, dependent strips will just be transformed and
      * we can skip calculating for effects.
-     * This way we can avoid an extra loop just for effects*/
+     * This way we can avoid an extra loop just for effects. */
     if (!(seq->type & SEQ_TYPE_EFFECT)) {
       BKE_sequence_calc(scene, seq);
     }
@@ -1595,7 +1582,7 @@ static int sequencer_slip_exec(bContext *C, wmOperator *op)
   int offset = RNA_int_get(op->ptr, "offset");
   bool success = false;
 
-  /* first recursively count the trimmed elements */
+  /* Recursively count the trimmed elements. */
   num_seq = slip_count_sequences_recursive(ed->seqbasep, true);
 
   if (num_seq == 0) {
@@ -1658,7 +1645,7 @@ static int sequencer_slip_modal(bContext *C, wmOperator *op, const wmEvent *even
   const bool has_numInput = hasNumInput(&data->num_input);
   bool handled = true;
 
-  /* Modal numinput active, try to handle numeric inputs first... */
+  /* Modal numinput active, try to handle numeric inputs. */
   if (event->val == KM_PRESS && has_numInput && handleNumInput(C, &data->num_input, event)) {
     float offset;
     applyNumInput(&data->num_input, &offset);
@@ -1691,7 +1678,7 @@ static int sequencer_slip_modal(bContext *C, wmOperator *op, const wmEvent *even
           mouse_x = event->mval[0];
         }
 
-        /* choose the side based on which side of the playhead the mouse is on */
+        /* Choose the side based on which side of the playhead the mouse is. */
         UI_view2d_region_to_view(v2d, mouse_x, 0, &mouseloc[0], &mouseloc[1]);
         offset = mouseloc[0] - data->init_mouseloc[0];
 
@@ -1772,7 +1759,7 @@ static int sequencer_slip_modal(bContext *C, wmOperator *op, const wmEvent *even
       break;
   }
 
-  /* Modal numinput inactive, try to handle numeric inputs last... */
+  /* Modal numinput inactive, try to handle numeric inputs. */
   if (!handled && event->val == KM_PRESS && handleNumInput(C, &data->num_input, event)) {
     float offset;
     applyNumInput(&data->num_input, &offset);
@@ -1791,18 +1778,18 @@ static int sequencer_slip_modal(bContext *C, wmOperator *op, const wmEvent *even
 
 void SEQUENCER_OT_slip(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Trim Strips";
   ot->idname = "SEQUENCER_OT_slip";
   ot->description = "Trim the contents of the active strip";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_slip_invoke;
   ot->modal = sequencer_slip_modal;
   ot->exec = sequencer_slip_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   RNA_def_int(ot->srna,
@@ -1816,7 +1803,7 @@ void SEQUENCER_OT_slip(struct wmOperatorType *ot)
               INT32_MAX);
 }
 
-/* mute operator */
+/* Mute operator. */
 static int sequencer_mute_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -1828,7 +1815,7 @@ static int sequencer_mute_exec(bContext *C, wmOperator *op)
 
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if ((seq->flag & SEQ_LOCK) == 0) {
-      if (selected) { /* mute unselected */
+      if (selected) {
         if (seq->flag & SELECT) {
           seq->flag |= SEQ_MUTE;
           BKE_sequence_invalidate_dependent(scene, seq);
@@ -1851,23 +1838,23 @@ static int sequencer_mute_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_mute(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Mute Strips";
   ot->idname = "SEQUENCER_OT_mute";
   ot->description = "Mute (un)selected strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_mute_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   RNA_def_boolean(
       ot->srna, "unselected", 0, "Unselected", "Mute unselected rather than selected strips");
 }
 
-/* unmute operator */
+/* Unmute operator. */
 static int sequencer_unmute_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -1879,7 +1866,7 @@ static int sequencer_unmute_exec(bContext *C, wmOperator *op)
 
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if ((seq->flag & SEQ_LOCK) == 0) {
-      if (selected) { /* unmute unselected */
+      if (selected) {
         if (seq->flag & SELECT) {
           seq->flag &= ~SEQ_MUTE;
           BKE_sequence_invalidate_dependent(scene, seq);
@@ -1902,23 +1889,23 @@ static int sequencer_unmute_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_unmute(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Unmute Strips";
   ot->idname = "SEQUENCER_OT_unmute";
   ot->description = "Unmute (un)selected strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_unmute_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   RNA_def_boolean(
       ot->srna, "unselected", 0, "Unselected", "Unmute unselected rather than selected strips");
 }
 
-/* lock operator */
+/* Lock operator. */
 static int sequencer_lock_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
@@ -1938,20 +1925,20 @@ static int sequencer_lock_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_lock(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Lock Strips";
   ot->idname = "SEQUENCER_OT_lock";
   ot->description = "Lock strips so they can't be transformed";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_lock_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-/* unlock operator */
+/* Unlock operator. */
 static int sequencer_unlock_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
@@ -1971,20 +1958,20 @@ static int sequencer_unlock_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_unlock(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Unlock Strips";
   ot->idname = "SEQUENCER_OT_unlock";
   ot->description = "Unlock strips so they can be transformed";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_unlock_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-/* reload operator */
+/* Reload operator. */
 static int sequencer_reload_exec(bContext *C, wmOperator *op)
 {
   Main *bmain = CTX_data_main(C);
@@ -2015,17 +2002,17 @@ void SEQUENCER_OT_reload(struct wmOperatorType *ot)
 {
   PropertyRNA *prop;
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Reload Strips";
   ot->idname = "SEQUENCER_OT_reload";
   ot->description = "Reload strips in the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_reload_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
-  ot->flag = OPTYPE_REGISTER; /* no undo, the data changed is stored outside 'main' */
+  /* Flags. */
+  ot->flag = OPTYPE_REGISTER; /* No undo, the data changed is stored outside 'main'. */
 
   prop = RNA_def_boolean(ot->srna,
                          "adjust_length",
@@ -2035,7 +2022,7 @@ void SEQUENCER_OT_reload(struct wmOperatorType *ot)
   RNA_def_property_flag(prop, PROP_SKIP_SAVE);
 }
 
-/* reload operator */
+/* Reload operator. */
 static bool sequencer_refresh_all_poll(bContext *C)
 {
   if (G.is_rendering) {
@@ -2058,12 +2045,12 @@ static int sequencer_refresh_all_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_refresh_all(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Refresh Sequencer";
   ot->idname = "SEQUENCER_OT_refresh_all";
   ot->description = "Refresh the sequencer editor";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_refresh_all_exec;
   ot->poll = sequencer_refresh_all_poll;
 }
@@ -2079,7 +2066,7 @@ static int sequencer_reassign_inputs_exec(bContext *C, wmOperator *op)
     BKE_report(op->reports, RPT_ERROR, error_msg);
     return OPERATOR_CANCELLED;
   }
-  /* see reassigning would create a cycle */
+  /* Check if reassigning would create recursivity. */
   if (seq_is_predecessor(seq1, last_seq) || seq_is_predecessor(seq2, last_seq) ||
       seq_is_predecessor(seq3, last_seq)) {
     BKE_report(op->reports, RPT_ERROR, "Cannot reassign inputs: no cycles allowed");
@@ -2114,16 +2101,16 @@ static bool sequencer_effect_poll(bContext *C)
 
 void SEQUENCER_OT_reassign_inputs(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Reassign Inputs";
   ot->idname = "SEQUENCER_OT_reassign_inputs";
   ot->description = "Reassign the inputs for the effect strip";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_reassign_inputs_exec;
   ot->poll = sequencer_effect_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
@@ -2149,20 +2136,20 @@ static int sequencer_swap_inputs_exec(bContext *C, wmOperator *op)
 }
 void SEQUENCER_OT_swap_inputs(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Swap Inputs";
   ot->idname = "SEQUENCER_OT_swap_inputs";
   ot->description = "Swap the first two inputs for the effect strip";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_swap_inputs_exec;
   ot->poll = sequencer_effect_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-/* split operator */
+/* Split operator. */
 static const EnumPropertyItem prop_split_types[] = {
     {SEQ_SPLIT_SOFT, "SOFT", 0, "Soft", ""},
     {SEQ_SPLIT_HARD, "HARD", 0, "Hard", ""},
@@ -2203,7 +2190,7 @@ static int sequencer_split_exec(bContext *C, wmOperator *op)
                              use_cursor_position,
                              split_seq_soft);
   }
-  if (changed) { /* got new strips ? */
+  if (changed) { /* Got new strips? */
     Sequence *seq;
     if (ignore_selection) {
       if (use_cursor_position) {
@@ -2246,7 +2233,7 @@ static int sequencer_split_exec(bContext *C, wmOperator *op)
       }
     }
     SEQ_END;
-    /* as last: */
+
     BKE_sequencer_sort(scene);
   }
   if (changed) {
@@ -2285,24 +2272,24 @@ static int sequencer_split_invoke(bContext *C, wmOperator *op, const wmEvent *ev
   }
   RNA_int_set(op->ptr, "channel", mouseloc[1]);
   RNA_enum_set(op->ptr, "side", split_side);
-  /*RNA_enum_set(op->ptr, "type", split_hard); */ /*This type is set from the key
-                                                     shortsplit */
+  /*RNA_enum_set(op->ptr, "type", split_hard); */
+
   return sequencer_split_exec(C, op);
 }
 
 void SEQUENCER_OT_split(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Split Strips";
   ot->idname = "SEQUENCER_OT_split";
   ot->description = "Split the selected strips in two";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_split_invoke;
   ot->exec = sequencer_split_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   PropertyRNA *prop;
@@ -2358,7 +2345,7 @@ void SEQUENCER_OT_split(struct wmOperatorType *ot)
 
 #undef SEQ_SIDE_MOUSE
 
-/* duplicate operator */
+/* Duplicate operator. */
 static int apply_unique_name_fn(Sequence *seq, void *arg_pt)
 {
   Scene *scene = (Scene *)arg_pt;
@@ -2385,7 +2372,7 @@ static int sequencer_add_duplicate_exec(bContext *C, wmOperator *UNUSED(op))
 
   if (nseqbase.first) {
     Sequence *seq = nseqbase.first;
-    /* rely on the nseqbase list being added at the end */
+    /* Rely on the nseqbase list being added at the end. */
     BLI_movelisttolist(ed->seqbasep, &nseqbase);
 
     for (; seq; seq = seq->next) {
@@ -2401,20 +2388,20 @@ static int sequencer_add_duplicate_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_duplicate(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Duplicate Strips";
   ot->idname = "SEQUENCER_OT_duplicate";
   ot->description = "Duplicate the selected strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_add_duplicate_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-/* delete operator */
+/* Delete operator. */
 static int sequencer_delete_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Main *bmain = CTX_data_main(C);
@@ -2425,7 +2412,7 @@ static int sequencer_delete_exec(bContext *C, wmOperator *UNUSED(op))
   bool nothing_selected = true;
 
   seq = BKE_sequencer_active_get(scene);
-  if (seq && seq->flag & SELECT) { /* avoid a loop since this is likely to be selected */
+  if (seq && seq->flag & SELECT) { /* Avoid a loop since this is likely to be selected. */
     nothing_selected = false;
   }
   else {
@@ -2441,7 +2428,7 @@ static int sequencer_delete_exec(bContext *C, wmOperator *UNUSED(op))
     return OPERATOR_FINISHED;
   }
 
-  /* for effects and modifiers, try to find a replacement input */
+  /* For effects and modifiers, try to find a replacement input. */
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if (!(seq->flag & SELECT)) {
       if ((seq->type & SEQ_TYPE_EFFECT)) {
@@ -2453,17 +2440,17 @@ static int sequencer_delete_exec(bContext *C, wmOperator *UNUSED(op))
     }
   }
 
-  /* delete all selected strips */
+  /* Delete all selected strips. */
   recurs_del_seq_flag(scene, ed->seqbasep, SELECT, 0);
 
-  /* updates lengths etc */
+  /* Update lengths, etc. */
   seq = ed->seqbasep->first;
   while (seq) {
     BKE_sequence_calc(scene, seq);
     seq = seq->next;
   }
 
-  /* free parent metas */
+  /* Free parent metas. */
   ms = ed->metastack.last;
   while (ms) {
     BKE_sequence_calc(scene, ms->parseq);
@@ -2482,8 +2469,8 @@ static int sequencer_delete_invoke(bContext *C, wmOperator *op, const wmEvent *e
   ARegion *region = CTX_wm_region(C);
 
   if (region->regiontype == RGN_TYPE_WINDOW) {
-    /* bounding box of 30 pixels is used for markers shortcuts,
-     * prevent conflict with markers shortcuts here
+    /* Bounding box of 30 pixels is used for markers shortcuts,
+     * prevent conflict with markers shortcuts here.
      */
     if (event->mval[1] <= 30) {
       return OPERATOR_PASS_THROUGH;
@@ -2496,35 +2483,35 @@ static int sequencer_delete_invoke(bContext *C, wmOperator *op, const wmEvent *e
 void SEQUENCER_OT_delete(wmOperatorType *ot)
 {
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Erase Strips";
   ot->idname = "SEQUENCER_OT_delete";
   ot->description = "Erase selected strips from the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_delete_invoke;
   ot->exec = sequencer_delete_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-/* offset clear operator */
+/* Offset clear operator. */
 static int sequencer_offset_clear_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
   Editing *ed = BKE_sequencer_editing_get(scene, false);
   Sequence *seq;
 
-  /* for effects, try to find a replacement input */
+  /* For effects, try to find a replacement input. */
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if ((seq->type & SEQ_TYPE_EFFECT) == 0 && (seq->flag & SELECT)) {
       seq->startofs = seq->endofs = seq->startstill = seq->endstill = 0;
     }
   }
 
-  /* updates lengths etc */
+  /* Update lengths, etc. */
   seq = ed->seqbasep->first;
   while (seq) {
     BKE_sequence_calc(scene, seq);
@@ -2547,20 +2534,20 @@ static int sequencer_offset_clear_exec(bContext *C, wmOperator *UNUSED(op))
 void SEQUENCER_OT_offset_clear(wmOperatorType *ot)
 {
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Clear Strip Offset";
   ot->idname = "SEQUENCER_OT_offset_clear";
   ot->description = "Clear strip offsets from the start and end frames";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_offset_clear_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-/* separate_images operator */
+/* Separate_images operator. */
 static int sequencer_separate_images_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -2572,13 +2559,13 @@ static int sequencer_separate_images_exec(bContext *C, wmOperator *op)
   int start_ofs, cfra, frame_end;
   int step = RNA_int_get(op->ptr, "length");
 
-  seq = ed->seqbasep->first; /* poll checks this is valid */
+  seq = ed->seqbasep->first; /* Poll checks this is valid. */
 
   while (seq) {
     if ((seq->flag & SELECT) && (seq->type == SEQ_TYPE_IMAGE) && (seq->len > 1)) {
       Sequence *seq_next;
 
-      /* remove seq so overlap tests don't conflict,
+      /* Remove seq so overlap tests don't conflict,
        * see seq_free_sequence below for the real freeing. */
       BLI_remlink(ed->seqbasep, seq);
       /* if (seq->ipo) id_us_min(&seq->ipo->id); */
@@ -2588,7 +2575,7 @@ static int sequencer_separate_images_exec(bContext *C, wmOperator *op)
       frame_end = BKE_sequence_tx_get_final_right(seq, false);
 
       while (cfra < frame_end) {
-        /* new seq */
+        /* New seq. */
         se = BKE_sequencer_give_stripelem(seq, cfra);
 
         seq_new = BKE_sequence_dupli_recursive(
@@ -2599,11 +2586,11 @@ static int sequencer_separate_images_exec(bContext *C, wmOperator *op)
         seq_new->len = 1;
         seq_new->endstill = step - 1;
 
-        /* new strip */
+        /* New strip. */
         strip_new = seq_new->strip;
         strip_new->us = 1;
 
-        /* new stripdata (only one element now!) */
+        /* New stripdata, only one element now. */
         /* Note this assume all elements (images) have the same dimension,
          * since we only copy the name here. */
         se_new = MEM_reallocN(strip_new->stripdata, sizeof(*se_new));
@@ -2634,7 +2621,6 @@ static int sequencer_separate_images_exec(bContext *C, wmOperator *op)
     }
   }
 
-  /* as last: */
   BKE_sequencer_sort(scene);
 
   WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, scene);
@@ -2644,25 +2630,25 @@ static int sequencer_separate_images_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_images_separate(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Separate Images";
   ot->idname = "SEQUENCER_OT_images_separate";
   ot->description = "On image sequence strips, it returns a strip for each image";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_separate_images_exec;
   ot->invoke = WM_operator_props_popup_confirm;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   RNA_def_int(ot->srna, "length", 1, 1, INT_MAX, "Length", "Length of each frame", 1, 1000);
 }
 
-/* META Operators */
+/* META Operators. */
 
-/* separate_meta_toggle operator */
+/* Separate_meta_toggle operator. */
 static int sequencer_meta_toggle_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
@@ -2671,7 +2657,7 @@ static int sequencer_meta_toggle_exec(bContext *C, wmOperator *UNUSED(op))
   MetaStack *ms;
 
   if (last_seq && last_seq->type == SEQ_TYPE_META && last_seq->flag & SELECT) {
-    /* Enter Metastrip */
+    /* Enter metastrip. */
     ms = MEM_mallocN(sizeof(MetaStack), "metastack");
     BLI_addtail(&ed->metastack, ms);
     ms->parseq = last_seq;
@@ -2683,7 +2669,7 @@ static int sequencer_meta_toggle_exec(bContext *C, wmOperator *UNUSED(op))
     BKE_sequencer_active_set(scene, NULL);
   }
   else {
-    /* Exit Metastrip (if possible) */
+    /* Exit metastrip if possible. */
 
     Sequence *seq;
 
@@ -2696,18 +2682,18 @@ static int sequencer_meta_toggle_exec(bContext *C, wmOperator *UNUSED(op))
 
     ed->seqbasep = ms->oldbasep;
 
-    /* for old files, update from meta */
+    /* For old files, update from meta. */
     if (ms->disp_range[0] == ms->disp_range[1]) {
       copy_v2_v2_int(ms->disp_range, &ms->parseq->startdisp);
     }
 
-    /* recalc all: the meta can have effects connected to it */
+    /* Recalc all: the meta can have effects connected to it. */
     for (seq = ed->seqbasep->first; seq; seq = seq->next) {
       BKE_sequence_calc(scene, seq);
     }
 
     /* 2.73+, keeping endpoints is important!
-     * moving them around means you can't usefully use metas in a complex edit. */
+     * Moving them around means you can't usefully use metas in a complex edit. */
 #if 1
     BKE_sequence_tx_set_final_left(ms->parseq, ms->disp_range[0]);
     BKE_sequence_tx_set_final_right(ms->parseq, ms->disp_range[1]);
@@ -2735,20 +2721,20 @@ static int sequencer_meta_toggle_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_meta_toggle(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Toggle Meta Strip";
   ot->idname = "SEQUENCER_OT_meta_toggle";
   ot->description = "Toggle a metastrip (to edit enclosed strips)";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_meta_toggle_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-/* separate_meta_make operator */
+/* Separate_meta_make operator. */
 static int sequencer_meta_make_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -2762,9 +2748,9 @@ static int sequencer_meta_make_exec(bContext *C, wmOperator *op)
     return OPERATOR_CANCELLED;
   }
 
-  /* remove all selected from main list, and put in meta */
+  /* Remove all selected from main list, and put in meta. */
 
-  seqm = BKE_sequence_alloc(ed->seqbasep, 1, 1, SEQ_TYPE_META); /* channel number set later */
+  seqm = BKE_sequence_alloc(ed->seqbasep, 1, 1, SEQ_TYPE_META); /* Channel number set later. */
   strcpy(seqm->name + 2, "MetaStrip");
   seqm->flag = SELECT;
 
@@ -2799,16 +2785,16 @@ static int sequencer_meta_make_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_meta_make(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Make Meta Strip";
   ot->idname = "SEQUENCER_OT_meta_make";
   ot->description = "Group selected strips into a metastrip";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_meta_make_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
@@ -2831,7 +2817,7 @@ static int seq_depends_on_meta(Sequence *seq, Sequence *seqm)
   }
 }
 
-/* separate_meta_make operator */
+/* Separate_meta_make operator. */
 static int sequencer_meta_separate_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
@@ -2854,7 +2840,7 @@ static int sequencer_meta_separate_exec(bContext *C, wmOperator *UNUSED(op))
   BLI_remlink(ed->seqbasep, last_seq);
   BKE_sequence_free(scene, last_seq);
 
-  /* empty meta strip, delete all effects depending on it */
+  /* Empty meta strip, delete all effects depending on it. */
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if ((seq->type & SEQ_TYPE_EFFECT) && seq_depends_on_meta(seq, last_seq)) {
       seq->flag |= SEQ_FLAG_DELETE;
@@ -2863,8 +2849,8 @@ static int sequencer_meta_separate_exec(bContext *C, wmOperator *UNUSED(op))
 
   recurs_del_seq_flag(scene, ed->seqbasep, SEQ_FLAG_DELETE, 0);
 
-  /* test for effects and overlap
-   * don't use SEQP_BEGIN since that would be recursive */
+  /* Test for effects and overlap
+   * don't use SEQP_BEGIN since that would be recursive. */
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if (seq->flag & SELECT) {
       seq->flag &= ~SEQ_OVERLAP;
@@ -2884,20 +2870,20 @@ static int sequencer_meta_separate_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_meta_separate(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "UnMeta Strip";
   ot->idname = "SEQUENCER_OT_meta_separate";
   ot->description = "Put the contents of a metastrip back in the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_meta_separate_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 }
 
-/* view_all operator */
+/* View_all operator. */
 static int sequencer_view_all_exec(bContext *C, wmOperator *op)
 {
   ARegion *region = CTX_wm_region(C);
@@ -2912,16 +2898,16 @@ static int sequencer_view_all_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_view_all(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "View All";
   ot->idname = "SEQUENCER_OT_view_all";
   ot->description = "View all the strips in the sequencer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_view_all_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER;
 }
 
@@ -2935,20 +2921,20 @@ static int sequencer_view_frame_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_view_frame(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Go to Current Frame";
   ot->idname = "SEQUENCER_OT_view_frame";
   ot->description = "Move the view to the playhead";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_view_frame_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = 0;
 }
 
-/* view_all operator */
+/* View_all operator. */
 static int sequencer_view_all_preview_exec(bContext *C, wmOperator *UNUSED(op))
 {
   bScreen *screen = CTX_wm_screen(C);
@@ -2965,7 +2951,7 @@ static int sequencer_view_all_preview_exec(bContext *C, wmOperator *UNUSED(op))
   UI_view2d_sync(screen, area, v2d, V2D_LOCK_COPY);
 
 #if 0
-  /* Like zooming on an image view */
+  /* Like zooming on an image view. */
   float zoomX, zoomY;
   int width, height, imgwidth, imgheight;
 
@@ -2977,11 +2963,11 @@ static int sequencer_view_all_preview_exec(bContext *C, wmOperator *UNUSED(op))
   imgwidth = (scene->r.size * scene->r.xsch) / 100;
   imgheight = (scene->r.size * scene->r.ysch) / 100;
 
-  /* Apply aspect, doesn't need to be that accurate */
+  /* Apply aspect, doesn't need to be that accurate. */
   imgwidth = (int)(imgwidth * (scene->r.xasp / scene->r.yasp));
 
   if (((imgwidth >= width) || (imgheight >= height)) && ((width > 0) && (height > 0))) {
-    /* Find the zoom value that will fit the image in the image space */
+    /* Find the zoom value that will fit the image in the image space. */
     zoomX = ((float)width) / ((float)imgwidth);
     zoomY = ((float)height) / ((float)imgheight);
     sseq->zoom = (zoomX < zoomY) ? zoomX : zoomY;
@@ -2999,16 +2985,16 @@ static int sequencer_view_all_preview_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_view_all_preview(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "View All";
   ot->idname = "SEQUENCER_OT_view_all_preview";
   ot->description = "Zoom preview to fit in the area";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_view_all_preview_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER;
 }
 
@@ -3034,16 +3020,16 @@ static int sequencer_view_zoom_ratio_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_view_zoom_ratio(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Sequencer View Zoom Ratio";
   ot->idname = "SEQUENCER_OT_view_zoom_ratio";
   ot->description = "Change zoom ratio of sequencer preview";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_view_zoom_ratio_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* properties */
+  /* Properties. */
   RNA_def_float(ot->srna,
                 "ratio",
                 1.0f,
@@ -3068,7 +3054,7 @@ static const EnumPropertyItem view_type_items[] = {
 };
 #endif
 
-/* view_all operator */
+/* View_all operator. */
 static int sequencer_view_toggle_exec(bContext *C, wmOperator *UNUSED(op))
 {
   SpaceSeq *sseq = (SpaceSeq *)CTX_wm_space_data(C);
@@ -3085,20 +3071,20 @@ static int sequencer_view_toggle_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_view_toggle(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "View Toggle";
   ot->idname = "SEQUENCER_OT_view_toggle";
   ot->description = "Toggle between sequencer views (sequence, preview, both)";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_view_toggle_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER;
 }
 
-/* view_selected operator */
+/* View_selected operator. */
 static int sequencer_view_selected_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -3148,7 +3134,7 @@ static int sequencer_view_selected_exec(bContext *C, wmOperator *op)
     cur_new.ymin = ymin;
     cur_new.ymax = ymax;
 
-    /* only zoom out vertically */
+    /* Only zoom out vertically. */
     if (orig_height > BLI_rctf_size_y(&cur_new)) {
       ymid = BLI_rctf_cent_y(&cur_new);
 
@@ -3167,16 +3153,16 @@ static int sequencer_view_selected_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_view_selected(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Frame Selected";
   ot->idname = "SEQUENCER_OT_view_selected";
   ot->description = "Zoom the sequencer on the selected strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_view_selected_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER;
 }
 
@@ -3199,7 +3185,7 @@ static bool strip_jump_internal(Scene *scene,
 
 static bool sequencer_strip_jump_poll(bContext *C)
 {
-  /* prevent changes during render */
+  /* Prevent changes during render. */
   if (G.is_rendering) {
     return 0;
   }
@@ -3207,14 +3193,14 @@ static bool sequencer_strip_jump_poll(bContext *C)
   return sequencer_edit_poll(C);
 }
 
-/* jump frame to edit point operator */
+/* Jump frame to edit point operator. */
 static int sequencer_strip_jump_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
   const bool next = RNA_boolean_get(op->ptr, "next");
   const bool center = RNA_boolean_get(op->ptr, "center");
 
-  /* currently do_skip_mute is always true */
+  /* Currently do_skip_mute is always true. */
   if (!strip_jump_internal(scene, next ? SEQ_SIDE_RIGHT : SEQ_SIDE_LEFT, true, center)) {
     return OPERATOR_CANCELLED;
   }
@@ -3226,19 +3212,19 @@ static int sequencer_strip_jump_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_strip_jump(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Jump to Strip";
   ot->idname = "SEQUENCER_OT_strip_jump";
   ot->description = "Move frame to previous edit point";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_strip_jump_exec;
   ot->poll = sequencer_strip_jump_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_UNDO;
 
-  /* properties */
+  /* Properties. */
   RNA_def_boolean(ot->srna, "next", true, "Next Strip", "");
   RNA_def_boolean(ot->srna, "center", true, "Use strip center", "");
 }
@@ -3296,7 +3282,7 @@ static int sequencer_swap_exec(bContext *C, wmOperator *op)
 
   if (seq) {
 
-    /* disallow effect strips */
+    /* Disallow effect strips. */
     if (BKE_sequence_effect_get_num_inputs(seq->type) >= 1 &&
         (seq->effectdata || seq->seq1 || seq->seq2 || seq->seq3)) {
       return OPERATOR_CANCELLED;
@@ -3315,7 +3301,7 @@ static int sequencer_swap_exec(bContext *C, wmOperator *op)
         break;
     }
 
-    // XXX - should be a generic function
+    /* XXX - Should be a generic function. */
     for (iseq = scene->ed->seqbasep->first; iseq; iseq = iseq->next) {
       if ((iseq->type & SEQ_TYPE_EFFECT) &&
           (seq_is_parent(iseq, active_seq) || seq_is_parent(iseq, seq))) {
@@ -3323,11 +3309,11 @@ static int sequencer_swap_exec(bContext *C, wmOperator *op)
       }
     }
 
-    /* do this in a new loop since both effects need to be calculated first */
+    /* Do this in a new loop since both effects need to be calculated first. */
     for (iseq = scene->ed->seqbasep->first; iseq; iseq = iseq->next) {
       if ((iseq->type & SEQ_TYPE_EFFECT) &&
           (seq_is_parent(iseq, active_seq) || seq_is_parent(iseq, seq))) {
-        /* this may now overlap */
+        /* This may now overlap. */
         if (BKE_sequence_test_overlap(ed->seqbasep, iseq)) {
           BKE_sequence_base_shuffle(ed->seqbasep, iseq, scene);
         }
@@ -3346,19 +3332,19 @@ static int sequencer_swap_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_swap(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Swap Strip";
   ot->idname = "SEQUENCER_OT_swap";
   ot->description = "Swap active strip with strip to the right or left";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_swap_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
-  /* properties */
+  /* Properties. */
   RNA_def_enum(
       ot->srna, "side", prop_side_lr_types, SEQ_SIDE_RIGHT, "Side", "Side of the strip to swap");
 }
@@ -3392,7 +3378,7 @@ static int sequencer_rendersize_exec(bContext *C, wmOperator *UNUSED(op))
   }
 
   if (se) {
-    // prevent setting the render size if sequence values aren't initialized
+    /* Prevent setting the render size if sequence values aren't initialized. */
     if ((se->orig_width > 0) && (se->orig_height > 0)) {
       scene->r.xsch = se->orig_width;
       scene->r.ysch = se->orig_height;
@@ -3406,19 +3392,17 @@ static int sequencer_rendersize_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_rendersize(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Set Render Size";
   ot->idname = "SEQUENCER_OT_rendersize";
   ot->description = "Set render size and aspect from active sequence";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_rendersize_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-
-  /* properties */
 }
 
 static void seq_copy_del_sound(Scene *scene, Sequence *seq)
@@ -3453,9 +3437,8 @@ static int sequencer_copy_exec(bContext *C, wmOperator *op)
   BKE_sequence_base_dupli_recursive(
       scene, scene, &nseqbase, ed->seqbasep, SEQ_DUPE_UNIQUE_NAME, LIB_ID_CREATE_NO_USER_REFCOUNT);
 
-  /* To make sure the copied strips have unique names between each other add
-   * them temporarily to the end of the original seqbase. (bug 25932)
-   */
+  /* Make sure that copied strips have unique names.
+   * Add them temporarily to the end of the original seqbase (bug 25932). */
   if (nseqbase.first) {
     Sequence *seq, *first_seq = nseqbase.first;
     BLI_movelisttolist(ed->seqbasep, &nseqbase);
@@ -3476,7 +3459,7 @@ static int sequencer_copy_exec(bContext *C, wmOperator *op)
 
   seqbase_clipboard_frame = scene->r.cfra;
 
-  /* Need to remove anything that references the current scene */
+  /* Remove anything that references the current scene. */
   LISTBASE_FOREACH (Sequence *, seq, &seqbase_clipboard) {
     seq_copy_del_sound(scene, seq);
   }
@@ -3490,26 +3473,24 @@ static int sequencer_copy_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_copy(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Copy";
   ot->idname = "SEQUENCER_OT_copy";
   ot->description = "Copy selected strips to clipboard";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_copy_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER;
-
-  /* properties */
 }
 
 static int sequencer_paste_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Main *bmain = CTX_data_main(C);
   Scene *scene = CTX_data_scene(C);
-  Editing *ed = BKE_sequencer_editing_get(scene, true); /* create if needed */
+  Editing *ed = BKE_sequencer_editing_get(scene, true); /* Create if needed. */
   ListBase nseqbase = {NULL, NULL};
   int ofs;
   Sequence *iseq, *iseq_first;
@@ -3525,7 +3506,7 @@ static int sequencer_paste_exec(bContext *C, wmOperator *UNUSED(op))
       scene, scene, &nseqbase, &seqbase_clipboard, SEQ_DUPE_UNIQUE_NAME, 0);
   BKE_sequencer_base_clipboard_pointers_store(bmain, &seqbase_clipboard);
 
-  /* transform pasted strips before adding */
+  /* Transform pasted strips before adding. */
   if (ofs) {
     for (iseq = nseqbase.first; iseq; iseq = iseq->next) {
       BKE_sequence_translate(scene, iseq, ofs);
@@ -3536,12 +3517,12 @@ static int sequencer_paste_exec(bContext *C, wmOperator *UNUSED(op))
 
   BLI_movelisttolist(ed->seqbasep, &nseqbase);
 
-  /* make sure the pasted strips have unique names between them */
+  /* Make sure, that pasted strips have unique names. */
   for (iseq = iseq_first; iseq; iseq = iseq->next) {
     BKE_sequencer_recursive_apply(iseq, apply_unique_name_fn, scene);
   }
 
-  /* ensure pasted strips don't overlap */
+  /* Ensure, that pasted strips don't overlap. */
   for (iseq = iseq_first; iseq; iseq = iseq->next) {
     if (BKE_sequence_test_overlap(ed->seqbasep, iseq)) {
       BKE_sequence_base_shuffle(ed->seqbasep, iseq, scene);
@@ -3556,19 +3537,17 @@ static int sequencer_paste_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_paste(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Paste";
   ot->idname = "SEQUENCER_OT_paste";
   ot->description = "Paste strips from clipboard";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_paste_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-
-  /* properties */
 }
 
 static int sequencer_swap_data_exec(bContext *C, wmOperator *op)
@@ -3619,22 +3598,20 @@ static int sequencer_swap_data_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_swap_data(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Sequencer Swap Data";
   ot->idname = "SEQUENCER_OT_swap_data";
   ot->description = "Swap 2 sequencer strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_swap_data_exec;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-
-  /* properties */
 }
 
-/* box select operator */
+/* Box select operator. */
 static int view_ghost_border_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -3642,7 +3619,7 @@ static int view_ghost_border_exec(bContext *C, wmOperator *op)
 
   rctf rect;
 
-  /* convert coordinates of rect to 'tot' rect coordinates */
+  /* Convert coordinates of rect to 'tot' rect coordinates. */
   WM_operator_properties_border_to_rctf(op, &rect);
   UI_view2d_region_to_view_rctf(v2d, &rect, &rect);
 
@@ -3669,30 +3646,28 @@ static int view_ghost_border_exec(bContext *C, wmOperator *op)
   return OPERATOR_FINISHED;
 }
 
-/* ****** Box Select ****** */
 void SEQUENCER_OT_view_ghost_border(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Border Offset View";
   ot->idname = "SEQUENCER_OT_view_ghost_border";
   ot->description = "Set the boundaries of the border used for offset-view";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = WM_gesture_box_invoke;
   ot->exec = view_ghost_border_exec;
   ot->modal = WM_gesture_box_modal;
   ot->poll = sequencer_view_preview_poll;
   ot->cancel = WM_gesture_box_cancel;
 
-  /* flags */
+  /* Flags. */
   ot->flag = 0;
 
-  /* rna */
+  /* Properties. */
   WM_operator_properties_gesture_box(ot);
 }
 
-/* rebuild_proxy operator */
-
+/* Rebuild_proxy operator. */
 static int sequencer_rebuild_proxy_invoke(bContext *C,
                                           wmOperator *op,
                                           const wmEvent *UNUSED(event))
@@ -3743,16 +3718,16 @@ static int sequencer_rebuild_proxy_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_rebuild_proxy(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Rebuild Proxy and Timecode Indices";
   ot->idname = "SEQUENCER_OT_rebuild_proxy";
   ot->description = "Rebuild all selected proxies and timecode indices using the job system";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_rebuild_proxy_invoke;
   ot->exec = sequencer_rebuild_proxy_exec;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER;
 }
 
@@ -3838,16 +3813,16 @@ static int sequencer_enable_proxies_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_enable_proxies(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Set Selected Strip Proxies";
   ot->idname = "SEQUENCER_OT_enable_proxies";
   ot->description = "Enable selected proxies on all selected Movie, Image and Meta strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_enable_proxies_invoke;
   ot->exec = sequencer_enable_proxies_exec;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER;
 
   RNA_def_boolean(ot->srna, "proxy_25", false, "25%", "");
@@ -3857,8 +3832,7 @@ void SEQUENCER_OT_enable_proxies(wmOperatorType *ot)
   RNA_def_boolean(ot->srna, "overwrite", false, "Overwrite", "");
 }
 
-/* change ops */
-
+/* Change effect inputs operator. */
 static const EnumPropertyItem prop_change_effect_input_types[] = {
     {0, "A_B", 0, "A -> B", ""},
     {1, "B_C", 0, "B -> C", ""},
@@ -3899,9 +3873,8 @@ static int sequencer_change_effect_input_exec(bContext *C, wmOperator *op)
 
   BKE_sequencer_update_changed_seq_and_deps(scene, seq, 0, 1);
 
-  /* important else we don't get the imbuf cache flushed */
+  /* Invalidate cache. */
   BKE_sequencer_free_imbuf(scene, &ed->seqbase, false);
-
   WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, scene);
 
   return OPERATOR_FINISHED;
@@ -3909,21 +3882,22 @@ static int sequencer_change_effect_input_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_change_effect_input(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Change Effect Input";
   ot->idname = "SEQUENCER_OT_change_effect_input";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_change_effect_input_exec;
   ot->poll = sequencer_effect_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   ot->prop = RNA_def_enum(
       ot->srna, "swap", prop_change_effect_input_types, 0, "Swap", "The effect inputs to swap");
 }
 
+/* Change effect type operator. */
 static int sequencer_change_effect_type_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -3931,14 +3905,14 @@ static int sequencer_change_effect_type_exec(bContext *C, wmOperator *op)
   Sequence *seq = BKE_sequencer_active_get(scene);
   const int new_type = RNA_enum_get(op->ptr, "type");
 
-  /* free previous effect and init new effect */
+  /* Free previous effect and init new effect. */
   struct SeqEffectHandle sh;
 
   if ((seq->type & SEQ_TYPE_EFFECT) == 0) {
     return OPERATOR_CANCELLED;
   }
 
-  /* can someone explain the logic behind only allowing to increase this,
+  /* Can someone explain the logic behind only allowing to increase this,
    * copied from 2.4x - campbell */
   if (BKE_sequence_effect_get_num_inputs(seq->type) <
       BKE_sequence_effect_get_num_inputs(new_type)) {
@@ -3955,10 +3929,8 @@ static int sequencer_change_effect_type_exec(bContext *C, wmOperator *op)
     sh.init(seq);
   }
 
-  /* update */
   BKE_sequencer_update_changed_seq_and_deps(scene, seq, 0, 1);
-
-  /* important else we don't get the imbuf cache flushed */
+  /* Invalidate cache. */
   BKE_sequencer_free_imbuf(scene, &ed->seqbase, false);
 
   WM_event_add_notifier(C, NC_SCENE | ND_SEQUENCER, scene);
@@ -3968,15 +3940,15 @@ static int sequencer_change_effect_type_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_change_effect_type(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Change Effect Type";
   ot->idname = "SEQUENCER_OT_change_effect_type";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_change_effect_type_exec;
   ot->poll = sequencer_effect_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   ot->prop = RNA_def_enum(ot->srna,
@@ -3987,6 +3959,7 @@ void SEQUENCER_OT_change_effect_type(struct wmOperatorType *ot)
                           "Sequencer effect type");
 }
 
+/* Change path operator. */
 static int sequencer_change_path_exec(bContext *C, wmOperator *op)
 {
   Main *bmain = CTX_data_main(C);
@@ -4002,7 +3975,7 @@ static int sequencer_change_path_exec(bContext *C, wmOperator *op)
     int len;
     StripElem *se;
 
-    /* need to find min/max frame for placeholders */
+    /* Need to find min/max frame for placeholders. */
     if (use_placeholders) {
       len = sequencer_image_seq_get_minmax_frame(op, seq->sfra, &minframe, &numdigits);
     }
@@ -4040,16 +4013,16 @@ static int sequencer_change_path_exec(bContext *C, wmOperator *op)
       RNA_END;
     }
 
-    /* reset these else we wont see all the images */
+    /* Reset these else we wont see all the images. */
     seq->anim_startofs = seq->anim_endofs = 0;
 
-    /* correct start/end frames so we don't move
-     * important not to set seq->len = len; allow the function to handle it */
+    /* Correct start/end frames so we don't move.
+     * Important not to set seq->len = len; allow the function to handle it. */
     BKE_sequence_reload_new_file(bmain, scene, seq, true);
 
     BKE_sequence_calc(scene, seq);
 
-    /* important else we don't get the imbuf cache flushed */
+    /* Invalidate cache. */
     BKE_sequencer_free_imbuf(scene, &ed->seqbase, false);
   }
   else if (ELEM(seq->type, SEQ_TYPE_SOUND_RAM, SEQ_TYPE_SOUND_HD)) {
@@ -4063,7 +4036,7 @@ static int sequencer_change_path_exec(bContext *C, wmOperator *op)
     BKE_sound_load(bmain, sound);
   }
   else {
-    /* lame, set rna filepath */
+    /* Lame, set rna filepath. */
     PointerRNA seq_ptr;
     PropertyRNA *prop;
     char filepath[FILE_MAX];
@@ -4092,7 +4065,7 @@ static int sequencer_change_path_invoke(bContext *C, wmOperator *op, const wmEve
   RNA_string_set(op->ptr, "directory", seq->strip->dir);
   RNA_string_set(op->ptr, "filepath", filepath);
 
-  /* set default display depending on seq type */
+  /* Set default display depending on seq type. */
   if (seq->type == SEQ_TYPE_IMAGE) {
     RNA_boolean_set(op->ptr, "filter_movie", false);
   }
@@ -4107,16 +4080,16 @@ static int sequencer_change_path_invoke(bContext *C, wmOperator *op, const wmEve
 
 void SEQUENCER_OT_change_path(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Change Data/Files";
   ot->idname = "SEQUENCER_OT_change_path";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_change_path_exec;
   ot->invoke = sequencer_change_path_invoke;
   ot->poll = sequencer_strip_has_path_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   WM_operator_properties_filesel(ot,
@@ -4134,6 +4107,7 @@ void SEQUENCER_OT_change_path(struct wmOperatorType *ot)
                   "Use placeholders for missing frames of the strip");
 }
 
+/* Export subtitles operator. */
 static int sequencer_export_subtitles_invoke(bContext *C,
                                              wmOperator *op,
                                              const wmEvent *UNUSED(event))
@@ -4176,7 +4150,7 @@ static int sequencer_export_subtitles_exec(bContext *C, wmOperator *op)
   RNA_string_get(op->ptr, "filepath", filepath);
   BLI_path_extension_ensure(filepath, sizeof(filepath), ".srt");
 
-  /* Avoid File write exceptions */
+  /* Avoid File write exceptions. */
   if (!BLI_exists(filepath)) {
     BLI_make_existing_file(filepath);
     if (!BLI_file_touch(filepath)) {
@@ -4203,7 +4177,7 @@ static int sequencer_export_subtitles_exec(bContext *C, wmOperator *op)
 
   BLI_listbase_sort(&text_seq, BKE_sequencer_cmp_time_startdisp);
 
-  /* time to open and write! */
+  /* Open and write file. */
   file = BLI_fopen(filepath, "w");
 
   for (seq = text_seq.first; seq; seq = seq_next) {
@@ -4246,17 +4220,17 @@ static bool sequencer_strip_is_text_poll(bContext *C)
 
 void SEQUENCER_OT_export_subtitles(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Export Subtitles";
   ot->idname = "SEQUENCER_OT_export_subtitles";
   ot->description = "Export .srt file containing text strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_export_subtitles_exec;
   ot->invoke = sequencer_export_subtitles_invoke;
   ot->poll = sequencer_strip_is_text_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   WM_operator_properties_filesel(ot,
@@ -4268,6 +4242,7 @@ void SEQUENCER_OT_export_subtitles(struct wmOperatorType *ot)
                                  FILE_SORT_ALPHA);
 }
 
+/* Set range to strips operator. */
 static int sequencer_set_range_to_strips_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -4316,16 +4291,16 @@ void SEQUENCER_OT_set_range_to_strips(struct wmOperatorType *ot)
 {
   PropertyRNA *prop;
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Set Range to Strips";
   ot->idname = "SEQUENCER_OT_set_range_to_strips";
   ot->description = "Set the frame range to the selected strips start and end";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_set_range_to_strips_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
   prop = RNA_def_boolean(ot->srna, "preview", false, "Preview", "Set the preview range instead");
diff --git a/source/blender/editors/space_sequencer/sequencer_intern.h b/source/blender/editors/space_sequencer/sequencer_intern.h
index f70bc06caf7..708682cd04f 100644
--- a/source/blender/editors/space_sequencer/sequencer_intern.h
+++ b/source/blender/editors/space_sequencer/sequencer_intern.h
@@ -27,7 +27,7 @@
 #include "DNA_sequence_types.h"
 #include "RNA_access.h"
 
-/* internal exports only */
+/* Internal exports only. */
 
 struct ARegion;
 struct ARegionType;
@@ -57,7 +57,7 @@ void sequencer_special_update_set(Sequence *seq);
 float sequence_handle_size_get_clamped(struct Sequence *seq, const float pixelx);
 
 /* UNUSED */
-// void seq_reset_imageofs(struct SpaceSeq *sseq);
+/* void seq_reset_imageofs(struct SpaceSeq *sseq); */
 
 struct ImBuf *sequencer_ibuf_get(struct Main *bmain,
                                  struct Depsgraph *depsgraph,
@@ -88,19 +88,19 @@ int seq_effect_find_selected(struct Scene *scene,
                              struct Sequence **r_selseq3,
                              const char **r_error_str);
 
-/* operator helpers */
+/* Operator helpers. */
 bool sequencer_edit_poll(struct bContext *C);
 /* UNUSED */
-// bool sequencer_strip_poll(struct bContext *C);
+/* bool sequencer_strip_poll(struct bContext *C); */
 bool sequencer_strip_has_path_poll(struct bContext *C);
 bool sequencer_view_preview_poll(struct bContext *C);
 bool sequencer_view_strips_poll(struct bContext *C);
 
-/* externs */
+/* Externs. */
 extern EnumPropertyItem sequencer_prop_effect_types[];
 extern EnumPropertyItem prop_side_types[];
 
-/* operators */
+/* Operators. */
 struct wmKeyConfig;
 struct wmOperatorType;
 
@@ -152,7 +152,7 @@ void SEQUENCER_OT_export_subtitles(struct wmOperatorType *ot);
 
 void SEQUENCER_OT_set_range_to_strips(struct wmOperatorType *ot);
 
-/* preview specific operators */
+/* Preview specific operators. */
 void SEQUENCER_OT_view_all_preview(struct wmOperatorType *ot);
 
 /* sequencer_select.c */
@@ -193,8 +193,8 @@ enum {
   SEQ_SELECT_LR_RIGHT,
 };
 
-/* defines used internally */
-#define SCE_MARKERS 0  // XXX - dummy
+/* Defines used internally. */
+#define SCE_MARKERS 0 /* XXX - dummy */
 
 /* sequencer_ops.c */
 void sequencer_operatortypes(void);
@@ -222,7 +222,7 @@ void SEQUENCER_OT_sample(struct wmOperatorType *ot);
 /* sequencer_preview.c */
 void sequencer_preview_add_sound(const struct bContext *C, struct Sequence *seq);
 
-/* sequencer_add */
+/* sequencer_add.c */
 int sequencer_image_seq_get_minmax_frame(struct wmOperator *op,
                                          int sfra,
                                          int *r_minframe,
diff --git a/source/blender/editors/space_sequencer/sequencer_modifier.c b/source/blender/editors/space_sequencer/sequencer_modifier.c
index b90dc5e10ff..e0f7179c3f9 100644
--- a/source/blender/editors/space_sequencer/sequencer_modifier.c
+++ b/source/blender/editors/space_sequencer/sequencer_modifier.c
@@ -35,7 +35,7 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
-/* own include */
+/* Own include. */
 #include "sequencer_intern.h"
 
 /*********************** Add modifier operator *************************/
diff --git a/source/blender/editors/space_sequencer/sequencer_ops.c b/source/blender/editors/space_sequencer/sequencer_ops.c
index 4296701366a..ac00838a079 100644
--- a/source/blender/editors/space_sequencer/sequencer_ops.c
+++ b/source/blender/editors/space_sequencer/sequencer_ops.c
@@ -32,7 +32,7 @@
 #include "ED_markers.h"
 #include "ED_select_utils.h"
 #include "ED_sequencer.h"
-#include "ED_transform.h" /* transform keymap */
+#include "ED_transform.h" /* Transform keymap. */
 
 #include "BKE_sequencer.h"
 
diff --git a/source/blender/editors/space_sequencer/sequencer_preview.c b/source/blender/editors/space_sequencer/sequencer_preview.c
index d50047c4839..7d416884721 100644
--- a/source/blender/editors/space_sequencer/sequencer_preview.c
+++ b/source/blender/editors/space_sequencer/sequencer_preview.c
@@ -52,9 +52,9 @@ typedef struct PreviewJobAudio {
   struct PreviewJobAudio *next, *prev;
   struct Main *bmain;
   bSound *sound;
-  int lr; /* sample left or right */
+  int lr; /* Sample left or right. */
   int startframe;
-  bool waveform; /* reload sound or waveform */
+  bool waveform; /* Reload sound or waveform. */
 } PreviewJobAudio;
 
 static void free_preview_job(void *data)
@@ -66,7 +66,7 @@ static void free_preview_job(void *data)
   MEM_freeN(pj);
 }
 
-/* only this runs inside thread */
+/* Only this runs inside thread. */
 static void preview_startjob(void *data, short *stop, short *do_update, float *progress)
 {
   PreviewJob *pj = data;
@@ -89,7 +89,7 @@ static void preview_startjob(void *data, short *stop, short *do_update, float *p
       while (previewjb) {
         sound = previewjb->sound;
 
-        /* make sure we cleanup the loading flag! */
+        /* Make sure we cleanup the loading flag! */
         BLI_spin_lock(sound->spinlock);
         sound->tags &= ~SOUND_TAGS_WAVEFORM_LOADING;
         BLI_spin_unlock(sound->spinlock);
@@ -127,7 +127,6 @@ static void preview_endjob(void *data)
 
 void sequencer_preview_add_sound(const bContext *C, Sequence *seq)
 {
-  /* first, get the preview job, if it exists */
   wmJob *wm_job;
   PreviewJob *pj;
   ScrArea *area = CTX_wm_area(C);
@@ -139,6 +138,7 @@ void sequencer_preview_add_sound(const bContext *C, Sequence *seq)
                        WM_JOB_PROGRESS,
                        WM_JOB_TYPE_SEQ_BUILD_PREVIEW);
 
+  /* Get the preview job if it exists. */
   pj = WM_jobs_customdata_get(wm_job);
 
   if (!pj) {
@@ -152,8 +152,6 @@ void sequencer_preview_add_sound(const bContext *C, Sequence *seq)
     WM_jobs_callbacks(wm_job, preview_startjob, NULL, NULL, preview_endjob);
   }
 
-  /* attempt to lock mutex of job here */
-
   audiojob->bmain = CTX_data_main(C);
   audiojob->sound = seq->sound;
 
diff --git a/source/blender/editors/space_sequencer/sequencer_scopes.c b/source/blender/editors/space_sequencer/sequencer_scopes.c
index 02912b2755f..b08c35623af 100644
--- a/source/blender/editors/space_sequencer/sequencer_scopes.c
+++ b/source/blender/editors/space_sequencer/sequencer_scopes.c
@@ -42,7 +42,7 @@ static void rgb_to_yuv_normalized(const float rgb[3], float yuv[3])
   yuv[1] = 0.492f * (rgb[2] - yuv[0]);
   yuv[2] = 0.877f * (rgb[0] - yuv[0]);
 
-  /* Normalize */
+  /* Normalize. */
   yuv[1] *= 255.0f / (122 * 2.0f);
   yuv[1] += 0.5f;
 
diff --git a/source/blender/editors/space_sequencer/sequencer_select.c b/source/blender/editors/space_sequencer/sequencer_select.c
index 810e1009ecb..c5472ed88e5 100644
--- a/source/blender/editors/space_sequencer/sequencer_select.c
+++ b/source/blender/editors/space_sequencer/sequencer_select.c
@@ -40,7 +40,7 @@
 
 #include "RNA_define.h"
 
-/* for menu/popup icons etc etc*/
+/* For menu, popup, icons, etc. */
 
 #include "ED_outliner.h"
 #include "ED_screen.h"
@@ -49,7 +49,7 @@
 
 #include "UI_view2d.h"
 
-/* own include */
+/* Own include. */
 #include "sequencer_intern.h"
 
 static void *find_nearest_marker(int UNUSED(d1), int UNUSED(d2))
@@ -147,7 +147,7 @@ static void select_active_side_range(ListBase *seqbase,
   }
 }
 
-/* used for mouse selection in SEQUENCER_OT_select */
+/* Used for mouse selection in SEQUENCER_OT_select */
 static void select_linked_time(ListBase *seqbase, Sequence *seq_link)
 {
   Sequence *seq;
@@ -158,7 +158,7 @@ static void select_linked_time(ListBase *seqbase, Sequence *seq_link)
       int right_match = (seq->enddisp == seq_link->enddisp) ? 1 : 0;
 
       if (left_match && right_match) {
-        /* a direct match, copy the selection settinhs */
+        /* Direct match, copy the selection settings. */
         seq->flag &= ~(SELECT | SEQ_LEFTSEL | SEQ_RIGHTSEL);
         seq->flag |= seq_link->flag & (SELECT | SEQ_LEFTSEL | SEQ_RIGHTSEL);
 
@@ -166,7 +166,7 @@ static void select_linked_time(ListBase *seqbase, Sequence *seq_link)
       }
       else if (seq_link->flag & SELECT && (left_match || right_match)) {
 
-        /* clear for reselection */
+        /* Clear for reselection. */
         seq->flag &= ~(SEQ_LEFTSEL | SEQ_RIGHTSEL);
 
         if (left_match && seq_link->flag & SEQ_LEFTSEL) {
@@ -248,12 +248,11 @@ static void select_neighbor_from_last(Scene *scene, int lr)
     }
   }
   if (changed) {
-    /* pass */
+    /* Pass. */
   }
 }
 #endif
 
-/* (de)select operator */
 static int sequencer_de_select_all_exec(bContext *C, wmOperator *op)
 {
   int action = RNA_enum_get(op->ptr, "action");
@@ -302,22 +301,21 @@ static int sequencer_de_select_all_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_select_all(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "(De)select All";
   ot->idname = "SEQUENCER_OT_select_all";
   ot->description = "Select or deselect all strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_de_select_all_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_UNDO;
 
   WM_operator_properties_select_all(ot);
 }
 
-/* (de)select operator */
 static int sequencer_select_inverse_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
@@ -343,16 +341,16 @@ static int sequencer_select_inverse_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_select_inverse(struct wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select Inverse";
   ot->idname = "SEQUENCER_OT_select_inverse";
   ot->description = "Select unselected strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_select_inverse_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_UNDO;
 }
 
@@ -385,18 +383,18 @@ static int sequencer_select_exec(bContext *C, wmOperator *op)
     wait_to_deselect_others = false;
   }
 
-  marker = find_nearest_marker(SCE_MARKERS, 1);  // XXX - dummy function for now
+  marker = find_nearest_marker(SCE_MARKERS, 1); /* XXX - dummy function for now */
 
   seq = find_nearest_seq(scene, v2d, &hand, mval);
 
-  // XXX - not nice, Ctrl+RMB needs to do left_right only when not over a strip
+  /* XXX - not nice, Ctrl+RMB needs to do left_right only when not over a strip */
   if (seq && linked_time && (left_right == SEQ_SELECT_LR_MOUSE)) {
     left_right = SEQ_SELECT_LR_NONE;
   }
 
   if (marker) {
     int oldflag;
-    /* select timeline marker */
+    /* Select timeline marker. */
     if (extend) {
       oldflag = marker->flag;
       if (oldflag & SELECT) {
@@ -415,7 +413,7 @@ static int sequencer_select_exec(bContext *C, wmOperator *op)
     ret_value = OPERATOR_FINISHED;
   }
   else if (left_right != SEQ_SELECT_LR_NONE) {
-    /* use different logic for this */
+    /* Use different logic for this. */
     float x;
     if (extend == false) {
       ED_sequencer_deselect_all(scene);
@@ -494,7 +492,7 @@ static int sequencer_select_exec(bContext *C, wmOperator *op)
         }
       }
 
-      /* On Alt selection, select the strip and bordering handles */
+      /* On Alt selection, select the strip and bordering handles. */
       if (linked_handle) {
         if (!ELEM(hand, SEQ_SIDE_LEFT, SEQ_SIDE_RIGHT)) {
           /* First click selects the strip and its adjacent handles (if valid).
@@ -510,7 +508,7 @@ static int sequencer_select_exec(bContext *C, wmOperator *op)
           select_surrounding_handles(scene, seq);
         }
         else {
-          /* always select the strip under the cursor */
+          /* Always select the strip under the cursor. */
           seq->flag |= SELECT;
 
           /* First click selects adjacent handles on that side.
@@ -635,21 +633,21 @@ void SEQUENCER_OT_select(wmOperatorType *ot)
   };
   PropertyRNA *prop;
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select";
   ot->idname = "SEQUENCER_OT_select";
   ot->description = "Select a strip (last selected becomes the \"active strip\")";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_select_exec;
   ot->invoke = WM_generic_select_invoke;
   ot->modal = WM_generic_select_modal;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_UNDO;
 
-  /* properties */
+  /* Properties. */
   WM_operator_properties_generic_select(ot);
   RNA_def_boolean(ot->srna, "extend", 0, "Extend", "Extend the selection");
   prop = RNA_def_boolean(ot->srna,
@@ -660,7 +658,7 @@ void SEQUENCER_OT_select(wmOperatorType *ot)
   RNA_def_property_flag(prop, PROP_SKIP_SAVE);
   RNA_def_boolean(
       ot->srna, "linked_handle", 0, "Linked Handle", "Select handles next to the active strip");
-  /* for animation this is an enum but atm having an enum isn't useful for us */
+  /* For animation this is enum but atm having an enum isn't useful for us. */
   RNA_def_enum(ot->srna,
                "left_right",
                sequencer_select_left_right_types,
@@ -671,7 +669,7 @@ void SEQUENCER_OT_select(wmOperatorType *ot)
       ot->srna, "linked_time", 0, "Linked Time", "Select other strips at the same time");
 }
 
-/* run recursively to select linked */
+/* Run recursively to select linked. */
 static bool select_more_less_seq__internal(Scene *scene, bool sel, const bool linked)
 {
   Editing *ed = BKE_sequencer_editing_get(scene, false);
@@ -693,7 +691,7 @@ static bool select_more_less_seq__internal(Scene *scene, bool sel, const bool li
   }
 
   if (!linked) {
-    /* if not linked we only want to touch each seq once, newseq */
+    /* If not linked we only want to touch each seq once, newseq. */
     for (seq = ed->seqbasep->first; seq; seq = seq->next) {
       seq->tmp = NULL;
     }
@@ -702,7 +700,7 @@ static bool select_more_less_seq__internal(Scene *scene, bool sel, const bool li
   for (seq = ed->seqbasep->first; seq; seq = seq->next) {
     if ((seq->flag & SELECT) == sel) {
       if (linked || (seq->tmp == NULL)) {
-        /* only get unselected neighbors */
+        /* Only get unselected neighbors. */
         neighbor = find_neighboring_sequence(scene, seq, SEQ_SIDE_LEFT, isel);
         if (neighbor) {
           if (sel) {
@@ -738,7 +736,6 @@ static bool select_more_less_seq__internal(Scene *scene, bool sel, const bool li
   return changed;
 }
 
-/* select more operator */
 static int sequencer_select_more_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
@@ -756,22 +753,19 @@ static int sequencer_select_more_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_select_more(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select More";
   ot->idname = "SEQUENCER_OT_select_more";
   ot->description = "Select more strips adjacent to the current selection";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_select_more_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-
-  /* properties */
 }
 
-/* select less operator */
 static int sequencer_select_less_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
@@ -789,22 +783,19 @@ static int sequencer_select_less_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_select_less(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select Less";
   ot->idname = "SEQUENCER_OT_select_less";
   ot->description = "Shrink the current selection of adjacent selected strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_select_less_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-
-  /* properties */
 }
 
-/* select pick linked operator (uses the mouse) */
 static int sequencer_select_linked_pick_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 {
   Scene *scene = CTX_data_scene(C);
@@ -815,10 +806,10 @@ static int sequencer_select_linked_pick_invoke(bContext *C, wmOperator *op, cons
   Sequence *mouse_seq;
   int selected, hand;
 
-  /* this works like UV, not mesh */
+  /* This works like UV, not mesh. */
   mouse_seq = find_nearest_seq(scene, v2d, &hand, event->mval);
   if (!mouse_seq) {
-    return OPERATOR_FINISHED; /* user error as with mesh?? */
+    return OPERATOR_FINISHED; /* User error as with mesh?? */
   }
 
   if (extend == 0) {
@@ -842,23 +833,22 @@ static int sequencer_select_linked_pick_invoke(bContext *C, wmOperator *op, cons
 
 void SEQUENCER_OT_select_linked_pick(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select Pick Linked";
   ot->idname = "SEQUENCER_OT_select_linked_pick";
   ot->description = "Select a chain of linked strips nearest to the mouse pointer";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_select_linked_pick_invoke;
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
-  /* properties */
+  /* Properties. */
   RNA_def_boolean(ot->srna, "extend", 0, "Extend", "Extend the selection");
 }
 
-/* select linked operator */
 static int sequencer_select_linked_exec(bContext *C, wmOperator *UNUSED(op))
 {
   Scene *scene = CTX_data_scene(C);
@@ -878,22 +868,19 @@ static int sequencer_select_linked_exec(bContext *C, wmOperator *UNUSED(op))
 
 void SEQUENCER_OT_select_linked(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select Linked";
   ot->idname = "SEQUENCER_OT_select_linked";
   ot->description = "Select all strips adjacent to the current selection";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_select_linked_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
-
-  /* properties */
 }
 
-/* select handles operator */
 static int sequencer_select_handles_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -928,19 +915,19 @@ static int sequencer_select_handles_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_select_handles(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select Handles";
   ot->idname = "SEQUENCER_OT_select_handles";
   ot->description = "Select gizmo handles on the sides of the selected strip";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_select_handles_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
-  /* properties */
+  /* Properties. */
   RNA_def_enum(ot->srna,
                "side",
                prop_side_types,
@@ -949,7 +936,6 @@ void SEQUENCER_OT_select_handles(wmOperatorType *ot)
                "The side of the handle that is selected");
 }
 
-/* select side operator */
 static int sequencer_select_side_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -993,19 +979,19 @@ static int sequencer_select_side_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_select_side(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select Side";
   ot->idname = "SEQUENCER_OT_select_side";
   ot->description = "Select strips on the nominated side of the selected strips";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->exec = sequencer_select_side_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
-  /* properties */
+  /* Properties. */
   RNA_def_enum(ot->srna,
                "side",
                prop_side_types,
@@ -1014,7 +1000,6 @@ void SEQUENCER_OT_select_side(wmOperatorType *ot)
                "The side to which the selection is applied");
 }
 
-/* box_select operator */
 static int sequencer_box_select_exec(bContext *C, wmOperator *op)
 {
   Scene *scene = CTX_data_scene(C);
@@ -1089,7 +1074,6 @@ static int sequencer_box_select_exec(bContext *C, wmOperator *op)
   return OPERATOR_FINISHED;
 }
 
-/* ****** Box Select ****** */
 static int sequencer_box_select_invoke(bContext *C, wmOperator *op, const wmEvent *event)
 {
   Scene *scene = CTX_data_scene(C);
@@ -1112,12 +1096,12 @@ void SEQUENCER_OT_select_box(wmOperatorType *ot)
 {
   PropertyRNA *prop;
 
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Box Select";
   ot->idname = "SEQUENCER_OT_select_box";
   ot->description = "Select strips using box selection";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sequencer_box_select_invoke;
   ot->exec = sequencer_box_select_exec;
   ot->modal = WM_gesture_box_modal;
@@ -1125,10 +1109,10 @@ void SEQUENCER_OT_select_box(wmOperatorType *ot)
 
   ot->poll = ED_operator_sequencer_active;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_UNDO;
 
-  /* properties */
+  /* Properties. */
   WM_operator_properties_gesture_box(ot);
   WM_operator_properties_select_operation_simple(ot);
 
@@ -1140,8 +1124,6 @@ void SEQUENCER_OT_select_box(wmOperatorType *ot)
   RNA_def_property_flag(prop, PROP_SKIP_SAVE);
 }
 
-/* ****** Selected Grouped ****** */
-
 enum {
   SEQ_SELECT_GROUP_TYPE,
   SEQ_SELECT_GROUP_TYPE_BASIC,
@@ -1366,7 +1348,7 @@ static bool select_grouped_effect_link(Editing *ed, Sequence *actseq, const int
        BKE_sequence_iterator_next(&iter)) {
     seq = iter.seq;
 
-    /* Ignore all seqs already selected! */
+    /* Ignore all seqs already selected. */
     /* Ignore all seqs not sharing some time with active one. */
     /* Ignore all seqs of incompatible types (audio vs video). */
     if (!SEQ_CHANNEL_CHECK(seq, channel) || (seq->flag & SELECT) || (seq->startdisp >= enddisp) ||
@@ -1375,7 +1357,7 @@ static bool select_grouped_effect_link(Editing *ed, Sequence *actseq, const int
       continue;
     }
 
-    /* If the seq is an effect one, we need extra checking! */
+    /* If the seq is an effect one, we need extra checking. */
     if (SEQ_IS_EFFECT(seq) && ((seq->seq1 && seq->seq1->tmp) || (seq->seq2 && seq->seq2->tmp) ||
                                (seq->seq3 && seq->seq3->tmp))) {
       if (startdisp > seq->startdisp) {
@@ -1398,7 +1380,7 @@ static bool select_grouped_effect_link(Editing *ed, Sequence *actseq, const int
       BKE_sequence_iterator_begin(ed, &iter, true);
     }
 
-    /* Video strips below active one, or any strip for audio (order do no matters here!). */
+    /* Video strips below active one, or any strip for audio (order doesn't matter here). */
     else if (seq->machine < machine || is_audio) {
       seq->flag |= SELECT;
       changed = true;
@@ -1476,20 +1458,20 @@ static int sequencer_select_grouped_exec(bContext *C, wmOperator *op)
 
 void SEQUENCER_OT_select_grouped(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Select Grouped";
   ot->description = "Select all strips grouped by various properties";
   ot->idname = "SEQUENCER_OT_select_grouped";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = WM_menu_invoke;
   ot->exec = sequencer_select_grouped_exec;
   ot->poll = sequencer_edit_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_REGISTER | OPTYPE_UNDO;
 
-  /* properties */
+  /* Properties. */
   ot->prop = RNA_def_enum(ot->srna, "type", sequencer_prop_select_grouped_types, 0, "Type", "");
   RNA_def_boolean(ot->srna,
                   "extend",
diff --git a/source/blender/editors/space_sequencer/sequencer_view.c b/source/blender/editors/space_sequencer/sequencer_view.c
index b2114eab62e..a890b770c83 100644
--- a/source/blender/editors/space_sequencer/sequencer_view.c
+++ b/source/blender/editors/space_sequencer/sequencer_view.c
@@ -46,7 +46,7 @@
 
 #include "UI_view2d.h"
 
-/* own include */
+/* Own include. */
 #include "sequencer_intern.h"
 
 /******************** sample backdrop operator ********************/
@@ -158,7 +158,7 @@ static void sample_apply(bContext *C, wmOperator *op, const wmEvent *event)
       info->colf[3] = fp[3];
       info->colfp = info->colf;
 
-      /* sequencer's image buffers are in non-linear space, need to make them linear */
+      /* Sequencer's image buffers are in non-linear space, need to make them linear. */
       copy_v4_v4(info->linearcol, info->colf);
       BKE_sequencer_pixel_from_sequencer_space_v4(scene, info->linearcol);
 
@@ -236,17 +236,17 @@ static bool sample_poll(bContext *C)
 
 void SEQUENCER_OT_sample(wmOperatorType *ot)
 {
-  /* identifiers */
+  /* Identifiers. */
   ot->name = "Sample Color";
   ot->idname = "SEQUENCER_OT_sample";
   ot->description = "Use mouse to sample color in current frame";
 
-  /* api callbacks */
+  /* Api callbacks. */
   ot->invoke = sample_invoke;
   ot->modal = sample_modal;
   ot->cancel = sample_cancel;
   ot->poll = sample_poll;
 
-  /* flags */
+  /* Flags. */
   ot->flag = OPTYPE_BLOCKING;
 }
diff --git a/source/blender/editors/space_sequencer/space_sequencer.c b/source/blender/editors/space_sequencer/space_sequencer.c
index ed8117fda31..e40fe91ae99 100644
--- a/source/blender/editors/space_sequencer/space_sequencer.c
+++ b/source/blender/editors/space_sequencer/space_sequencer.c
@@ -43,7 +43,7 @@
 #include "ED_screen.h"
 #include "ED_space_api.h"
 #include "ED_view3d.h"
-#include "ED_view3d_offscreen.h" /* only for sequencer view3d drawing callback */
+#include "ED_view3d_offscreen.h" /* Only for sequencer view3d drawing callback. */
 
 #include "WM_api.h"
 #include "WM_message.h"
@@ -57,7 +57,8 @@
 
 #include "IMB_imbuf.h"
 
-#include "sequencer_intern.h"  // own include
+/* Own include. */
+#include "sequencer_intern.h"
 
 /**************************** common state *****************************/
 
@@ -97,7 +98,7 @@ static SpaceLink *sequencer_new(const ScrArea *UNUSED(area), const Scene *scene)
   sseq->mainb = SEQ_DRAW_IMG_IMBUF;
   sseq->flag = SEQ_SHOW_GPENCIL | SEQ_USE_ALPHA | SEQ_SHOW_MARKERS;
 
-  /* tool header */
+  /* Tool header. */
   region = MEM_callocN(sizeof(ARegion), "tool header for sequencer");
 
   BLI_addtail(&sseq->regionbase, region);
@@ -105,14 +106,14 @@ static SpaceLink *sequencer_new(const ScrArea *UNUSED(area), const Scene *scene)
   region->alignment = (U.uiflag & USER_HEADER_BOTTOM) ? RGN_ALIGN_BOTTOM : RGN_ALIGN_TOP;
   region->flag = RGN_FLAG_HIDDEN | RGN_FLAG_HIDDEN_BY_USER;
 
-  /* header */
+  /* Header. */
   region = MEM_callocN(sizeof(ARegion), "header for sequencer");
 
   BLI_addtail(&sseq->regionbase, region);
   region->regiontype = RGN_TYPE_HEADER;
   region->alignment = (U.uiflag & USER_HEADER_BOTTOM) ? RGN_ALIGN_BOTTOM : RGN_ALIGN_TOP;
 
-  /* buttons/list view */
+  /* Buttons/list view. */
   region = MEM_callocN(sizeof(ARegion), "buttons for sequencer");
 
   BLI_addtail(&sseq->regionbase, region);
@@ -120,7 +121,7 @@ static SpaceLink *sequencer_new(const ScrArea *UNUSED(area), const Scene *scene)
   region->alignment = RGN_ALIGN_RIGHT;
   region->flag = RGN_FLAG_HIDDEN;
 
-  /* toolbar */
+  /* Toolbar. */
   region = MEM_callocN(sizeof(ARegion), "tools for sequencer");
 
   BLI_addtail(&sseq->regionbase, region);
@@ -128,19 +129,19 @@ static SpaceLink *sequencer_new(const ScrArea *UNUSED(area), const Scene *scene)
   region->alignment = RGN_ALIGN_LEFT;
   region->flag = RGN_FLAG_HIDDEN;
 
-  /* preview region */
-  /* NOTE: if you change values here, also change them in sequencer_init_preview_region */
+  /* Preview region. */
+  /* NOTE: if you change values here, also change them in sequencer_init_preview_region. */
   region = MEM_callocN(sizeof(ARegion), "preview region for sequencer");
   BLI_addtail(&sseq->regionbase, region);
   region->regiontype = RGN_TYPE_PREVIEW;
   region->alignment = RGN_ALIGN_TOP;
   region->flag |= RGN_FLAG_HIDDEN;
-  /* for now, aspect ratio should be maintained, and zoom is clamped within sane default limits */
+  /* For now, aspect ratio should be maintained, and zoom is clamped within sane default limits. */
   region->v2d.keepzoom = V2D_KEEPASPECT | V2D_KEEPZOOM | V2D_LIMITZOOM;
   region->v2d.minzoom = 0.001f;
   region->v2d.maxzoom = 1000.0f;
-  region->v2d.tot.xmin = -960.0f; /* 1920 width centered */
-  region->v2d.tot.ymin = -540.0f; /* 1080 height centered */
+  region->v2d.tot.xmin = -960.0f; /* 1920 width centered. */
+  region->v2d.tot.ymin = -540.0f; /* 1080 height centered. */
   region->v2d.tot.xmax = 960.0f;
   region->v2d.tot.ymax = 540.0f;
   region->v2d.min[0] = 0.0f;
@@ -151,14 +152,13 @@ static SpaceLink *sequencer_new(const ScrArea *UNUSED(area), const Scene *scene)
   region->v2d.align = V2D_ALIGN_FREE;
   region->v2d.keeptot = V2D_KEEPTOT_FREE;
 
-  /* main region */
+  /* Main region. */
   region = MEM_callocN(sizeof(ARegion), "main region for sequencer");
 
   BLI_addtail(&sseq->regionbase, region);
   region->regiontype = RGN_TYPE_WINDOW;
 
-  /* seq space goes from (0,8) to (0, efra) */
-
+  /* Seq space goes from (0,8) to (0, efra). */
   region->v2d.tot.xmin = 0.0f;
   region->v2d.tot.ymin = 0.0f;
   region->v2d.tot.xmax = scene->r.efra;
@@ -184,13 +184,13 @@ static SpaceLink *sequencer_new(const ScrArea *UNUSED(area), const Scene *scene)
   return (SpaceLink *)sseq;
 }
 
-/* not spacelink itself */
+/* Not spacelink itself. */
 static void sequencer_free(SpaceLink *sl)
 {
   SpaceSeq *sseq = (SpaceSeq *)sl;
   SequencerScopes *scopes = &sseq->scopes;
 
-  // XXX  if (sseq->gpd) BKE_gpencil_free(sseq->gpd);
+  /* XXX  if (sseq->gpd) BKE_gpencil_free(sseq->gpd); */
 
   if (scopes->zebra_ibuf) {
     IMB_freeImBuf(scopes->zebra_ibuf);
@@ -213,7 +213,7 @@ static void sequencer_free(SpaceLink *sl)
   }
 }
 
-/* spacetype; init callback */
+/* Spacetype init callback. */
 static void sequencer_init(struct wmWindowManager *UNUSED(wm), ScrArea *UNUSED(area))
 {
 }
@@ -300,7 +300,7 @@ static void sequencer_refresh(const bContext *C, ScrArea *area)
           region_preview->alignment = RGN_ALIGN_TOP;
           view_changed = true;
         }
-        /* Final check that both preview and main height are reasonable! */
+        /* Final check that both preview and main height are reasonable. */
         if (region_preview->sizey < 10 || region_main->sizey < 10 ||
             region_preview->sizey + region_main->sizey > height) {
           region_preview->sizey = (int)(height * 0.4f + 0.5f);
@@ -321,8 +321,8 @@ static SpaceLink *sequencer_duplicate(SpaceLink *sl)
 {
   SpaceSeq *sseqn = MEM_dupallocN(sl);
 
-  /* clear or remove stuff from old */
-  // XXX  sseq->gpd = gpencil_data_duplicate(sseq->gpd, false);
+  /* Clear or remove stuff from old. */
+  /* XXX  sseq->gpd = gpencil_data_duplicate(sseq->gpd, false); */
 
   memset(&sseqn->scopes, 0, sizeof(sseqn->scopes));
 
@@ -334,7 +334,7 @@ static void sequencer_listener(wmWindow *UNUSED(win),
                                wmNotifier *wmn,
                                Scene *UNUSED(scene))
 {
-  /* context changes */
+  /* Context changes. */
   switch (wmn->category) {
     case NC_SCENE:
       switch (wmn->data) {
@@ -370,7 +370,7 @@ static bool image_drop_poll(bContext *C,
   int hand;
 
   if (drag->type == WM_DRAG_PATH) {
-    if (ELEM(drag->icon, ICON_FILE_IMAGE, ICON_FILE_BLANK)) { /* rule might not work? */
+    if (ELEM(drag->icon, ICON_FILE_IMAGE, ICON_FILE_BLANK)) { /* Rule might not work? */
       if (find_nearest_seq(scene, &region->v2d, &hand, event->mval) == NULL) {
         return 1;
       }
@@ -390,7 +390,7 @@ static bool movie_drop_poll(bContext *C,
   int hand;
 
   if (drag->type == WM_DRAG_PATH) {
-    if (ELEM(drag->icon, 0, ICON_FILE_MOVIE, ICON_FILE_BLANK)) { /* rule might not work? */
+    if (ELEM(drag->icon, 0, ICON_FILE_MOVIE, ICON_FILE_BLANK)) { /* Rule might not work? */
       if (find_nearest_seq(scene, &region->v2d, &hand, event->mval) == NULL) {
         return 1;
       }
@@ -409,7 +409,7 @@ static bool sound_drop_poll(bContext *C,
   int hand;
 
   if (drag->type == WM_DRAG_PATH) {
-    if (ELEM(drag->icon, ICON_FILE_SOUND, ICON_FILE_BLANK)) { /* rule might not work? */
+    if (ELEM(drag->icon, ICON_FILE_SOUND, ICON_FILE_BLANK)) { /* Rule might not work? */
       if (find_nearest_seq(scene, &region->v2d, &hand, event->mval) == NULL) {
         return 1;
       }
@@ -420,7 +420,7 @@ static bool sound_drop_poll(bContext *C,
 
 static void sequencer_drop_copy(wmDrag *drag, wmDropBox *drop)
 {
-  /* copy drag path to properties */
+  /* Copy drag path to properties. */
   if (RNA_struct_find_property(drop->ptr, "filepath")) {
     RNA_string_set(drop->ptr, "filepath", drag->path);
   }
@@ -439,7 +439,7 @@ static void sequencer_drop_copy(wmDrag *drag, wmDropBox *drop)
   }
 }
 
-/* this region dropbox definition */
+/* This region dropbox definition. */
 static void sequencer_dropboxes(void)
 {
   ListBase *lb = WM_dropboxmap_find("Sequencer", SPACE_SEQ, RGN_TYPE_WINDOW);
@@ -452,7 +452,7 @@ static void sequencer_dropboxes(void)
 /* ************* end drop *********** */
 
 /* DO NOT make this static, this hides the symbol and breaks API generation script. */
-extern const char *sequencer_context_dir[]; /* quiet warning. */
+extern const char *sequencer_context_dir[]; /* Quiet warning. */
 const char *sequencer_context_dir[] = {"edit_mask", NULL};
 
 static int sequencer_context(const bContext *C, const char *member, bContextDataResult *result)
@@ -489,7 +489,7 @@ static void sequencer_gizmos(void)
 }
 
 /* *********************** sequencer (main) region ************************ */
-/* add handlers, stuff you only do once or on area/region changes */
+/* Add handlers, stuff you only do once or on area/region changes. */
 static void sequencer_main_region_init(wmWindowManager *wm, ARegion *region)
 {
   wmKeyMap *keymap;
@@ -505,19 +505,19 @@ static void sequencer_main_region_init(wmWindowManager *wm, ARegion *region)
   keymap = WM_keymap_ensure(wm->defaultconf, "SequencerCommon", SPACE_SEQ, 0);
   WM_event_add_keymap_handler_v2d_mask(&region->handlers, keymap);
 
-  /* own keymap */
+  /* Own keymap. */
   keymap = WM_keymap_ensure(wm->defaultconf, "Sequencer", SPACE_SEQ, 0);
   WM_event_add_keymap_handler_v2d_mask(&region->handlers, keymap);
 
-  /* add drop boxes */
+  /* Add drop boxes. */
   lb = WM_dropboxmap_find("Sequencer", SPACE_SEQ, RGN_TYPE_WINDOW);
 
   WM_event_add_dropbox_handler(&region->handlers, lb);
 }
 
+/* Strip editing timeline. */
 static void sequencer_main_region_draw(const bContext *C, ARegion *region)
 {
-  /* NLE - strip editing timeline interface */
   draw_timeline_seq(C, region);
 }
 
@@ -527,14 +527,14 @@ static void sequencer_main_region_listener(wmWindow *UNUSED(win),
                                            wmNotifier *wmn,
                                            const Scene *UNUSED(scene))
 {
-  /* context changes */
+  /* Context changes. */
   switch (wmn->category) {
     case NC_SCENE:
       switch (wmn->data) {
         case ND_FRAME:
         case ND_FRAME_RANGE:
         case ND_MARKERS:
-        case ND_RENDER_OPTIONS: /* for FPS and FPS Base */
+        case ND_RENDER_OPTIONS: /* For FPS and FPS Base. */
         case ND_SEQUENCER:
         case ND_RENDER_RESULT:
           ED_region_tag_redraw(region);
@@ -625,7 +625,7 @@ static void sequencer_main_region_message_subscribe(const struct bContext *UNUSE
 }
 
 /* *********************** header region ************************ */
-/* add handlers, stuff you only do once or on area/region changes */
+/* Add handlers, stuff you only do once or on area/region changes. */
 static void sequencer_header_region_init(wmWindowManager *UNUSED(wm), ARegion *region)
 {
   ED_region_header_init(region);
@@ -637,7 +637,7 @@ static void sequencer_header_region_draw(const bContext *C, ARegion *region)
 }
 
 /* *********************** toolbar region ************************ */
-/* add handlers, stuff you only do once or on area/region changes */
+/* Add handlers, stuff you only do once or on area/region changes. */
 static void sequencer_tools_region_init(wmWindowManager *wm, ARegion *region)
 {
   wmKeyMap *keymap;
@@ -668,7 +668,7 @@ static void sequencer_preview_region_init(wmWindowManager *wm, ARegion *region)
   keymap = WM_keymap_ensure(wm->defaultconf, "SequencerCommon", SPACE_SEQ, 0);
   WM_event_add_keymap_handler_v2d_mask(&region->handlers, keymap);
 
-  /* own keymap */
+  /* Own keymap. */
   keymap = WM_keymap_ensure(wm->defaultconf, "SequencerPreview", SPACE_SEQ, 0);
   WM_event_add_keymap_handler_v2d_mask(&region->handlers, keymap);
 }
@@ -722,7 +722,7 @@ static void sequencer_preview_region_listener(wmWindow *UNUSED(win),
                                               wmNotifier *wmn,
                                               const Scene *UNUSED(scene))
 {
-  /* context changes */
+  /* Context changes. */
   switch (wmn->category) {
     case NC_GPENCIL:
       if (ELEM(wmn->action, NA_EDITED, NA_SELECTED)) {
@@ -769,7 +769,7 @@ static void sequencer_preview_region_listener(wmWindow *UNUSED(win),
 
 /* *********************** buttons region ************************ */
 
-/* add handlers, stuff you only do once or on area/region changes */
+/* Add handlers, stuff you only do once or on area/region changes. */
 static void sequencer_buttons_region_init(wmWindowManager *wm, ARegion *region)
 {
   wmKeyMap *keymap;
@@ -792,7 +792,7 @@ static void sequencer_buttons_region_listener(wmWindow *UNUSED(win),
                                               wmNotifier *wmn,
                                               const Scene *UNUSED(scene))
 {
-  /* context changes */
+  /* Context changes. */
   switch (wmn->category) {
     case NC_GPENCIL:
       if (ELEM(wmn->action, NA_EDITED, NA_SELECTED)) {
@@ -837,7 +837,7 @@ static void sequencer_id_remap(ScrArea *UNUSED(area), SpaceLink *slink, ID *old_
 
 /* ************************************* */
 
-/* only called once, from space/spacetypes.c */
+/* Only called once, from space/spacetypes.c. */
 void ED_spacetype_sequencer(void)
 {
   SpaceType *st = MEM_callocN(sizeof(SpaceType), "spacetype sequencer");
@@ -859,7 +859,8 @@ void ED_spacetype_sequencer(void)
   st->listener = sequencer_listener;
   st->id_remap = sequencer_id_remap;
 
-  /* regions: main window */
+  /* Create regions: */
+  /* Main window. */
   art = MEM_callocN(sizeof(ARegionType), "spacetype sequencer region");
   art->regionid = RGN_TYPE_WINDOW;
   art->init = sequencer_main_region_init;
@@ -867,10 +868,9 @@ void ED_spacetype_sequencer(void)
   art->listener = sequencer_main_region_listener;
   art->message_subscribe = sequencer_main_region_message_subscribe;
   art->keymapflag = ED_KEYMAP_TOOL | ED_KEYMAP_VIEW2D | ED_KEYMAP_FRAMES | ED_KEYMAP_ANIMATION;
-
   BLI_addhead(&st->regiontypes, art);
 
-  /* preview */
+  /* Preview. */
   art = MEM_callocN(sizeof(ARegionType), "spacetype sequencer region");
   art->regionid = RGN_TYPE_PREVIEW;
   art->init = sequencer_preview_region_init;
@@ -880,7 +880,7 @@ void ED_spacetype_sequencer(void)
                     ED_KEYMAP_GPENCIL;
   BLI_addhead(&st->regiontypes, art);
 
-  /* regions: listview/buttons */
+  /* Listview/buttons. */
   art = MEM_callocN(sizeof(ARegionType), "spacetype sequencer region");
   art->regionid = RGN_TYPE_UI;
   art->prefsizex = UI_SIDEBAR_PANEL_WIDTH * 1.3f;
@@ -892,7 +892,7 @@ void ED_spacetype_sequencer(void)
   BLI_addhead(&st->regiontypes, art);
 
   sequencer_buttons_register(art);
-  /* regions: tool(bar) */
+  /* Toolbar. */
   art = MEM_callocN(sizeof(ARegionType), "spacetype sequencer tools region");
   art->regionid = RGN_TYPE_TOOLS;
   art->prefsizex = 58; /* XXX */
@@ -904,7 +904,7 @@ void ED_spacetype_sequencer(void)
   art->draw = sequencer_tools_region_draw;
   BLI_addhead(&st->regiontypes, art);
 
-  /* regions: tool header */
+  /* Tool header. */
   art = MEM_callocN(sizeof(ARegionType), "spacetype sequencer tool header region");
   art->regionid = RGN_TYPE_TOOL_HEADER;
   art->prefsizey = HEADERY;
@@ -915,7 +915,7 @@ void ED_spacetype_sequencer(void)
   art->message_subscribe = ED_area_do_mgs_subscribe_for_tool_header;
   BLI_addhead(&st->regiontypes, art);
 
-  /* regions: header */
+  /* Header. */
   art = MEM_callocN(sizeof(ARegionType), "spacetype sequencer region");
   art->regionid = RGN_TYPE_HEADER;
   art->prefsizey = HEADERY;
@@ -924,16 +924,15 @@ void ED_spacetype_sequencer(void)
   art->init = sequencer_header_region_init;
   art->draw = sequencer_header_region_draw;
   art->listener = sequencer_main_region_listener;
-
   BLI_addhead(&st->regiontypes, art);
 
-  /* regions: hud */
+  /* Hud. */
   art = ED_area_type_hud(st->spaceid);
   BLI_addhead(&st->regiontypes, art);
 
   BKE_spacetype_register(st);
 
-  /* set the sequencer callback when not in background mode */
+  /* Set the sequencer callback when not in background mode. */
   if (G.background == 0) {
     sequencer_view3d_fn = ED_view3d_draw_offscreen_imbuf_simple;
   }