Cleanup: Split SEQ_sequencer.h file

82 files changed, 1238 insertions, 611 deletions

diff --git a/source/blender/blenkernel/intern/bpath.c b/source/blender/blenkernel/intern/bpath.c
index f624d0ae057..762ced7dc5f 100644
--- a/source/blender/blenkernel/intern/bpath.c
+++ b/source/blender/blenkernel/intern/bpath.c
@@ -78,7 +78,7 @@
 
 #include "CLG_log.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 #ifndef _MSC_VER
 #  include "BLI_strict_flags.h"
diff --git a/source/blender/blenkernel/intern/image.c b/source/blender/blenkernel/intern/image.c
index 090ab571542..ab57d14d2cf 100644
--- a/source/blender/blenkernel/intern/image.c
+++ b/source/blender/blenkernel/intern/image.c
@@ -93,7 +93,7 @@
 
 #include "RE_pipeline.h"
 
-#include "SEQ_sequencer.h" /* seq_foreground_frame_get() */
+#include "SEQ_utils.h" /* SEQ_get_topmost_sequence() */
 
 #include "GPU_texture.h"
 
diff --git a/source/blender/blenkernel/intern/ipo.c b/source/blender/blenkernel/intern/ipo.c
index 0e611b21304..1ab6e61e20e 100644
--- a/source/blender/blenkernel/intern/ipo.c
+++ b/source/blender/blenkernel/intern/ipo.c
@@ -74,7 +74,7 @@
 
 #include "MEM_guardedalloc.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 #include "BLO_read_write.h"
 
diff --git a/source/blender/blenkernel/intern/scene.c b/source/blender/blenkernel/intern/scene.c
index 7acd54b6af1..c099fdb0e19 100644
--- a/source/blender/blenkernel/intern/scene.c
+++ b/source/blender/blenkernel/intern/scene.c
@@ -109,7 +109,13 @@
 
 #include "RE_engine.h"
 
+#include "SEQ_edit.h"
+#include "SEQ_iterator.h"
+#include "SEQ_modifier.h"
+#include "SEQ_proxy.h"
+#include "SEQ_relations.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_sound.h"
 
 #include "BLO_read_write.h"
 
@@ -3733,6 +3739,6 @@ void BKE_scene_eval_sequencer_sequences(Depsgraph *depsgraph, Scene *scene)
     }
   }
   SEQ_ALL_END;
-  SEQ_sound_update_muting(scene->ed);
+  SEQ_edit_update_muting(scene->ed);
   SEQ_sound_update_bounds_all(scene);
 }
diff --git a/source/blender/blenkernel/intern/sound.c b/source/blender/blenkernel/intern/sound.c
index d167fc4e51f..78729fb9261 100644
--- a/source/blender/blenkernel/intern/sound.c
+++ b/source/blender/blenkernel/intern/sound.c
@@ -68,6 +68,7 @@
 #include "BLO_read_write.h"
 
 #include "SEQ_sequencer.h"
+#include "SEQ_sound.h"
 
 static void sound_free_audio(bSound *sound);
 
diff --git a/source/blender/blenloader/intern/readfile.c b/source/blender/blenloader/intern/readfile.c
index 73606db9a41..b61abd4ed06 100644
--- a/source/blender/blenloader/intern/readfile.c
+++ b/source/blender/blenloader/intern/readfile.c
@@ -105,6 +105,9 @@
 #include "BLO_readfile.h"
 #include "BLO_undofile.h"
 
+#include "SEQ_clipboard.h"
+#include "SEQ_iterator.h"
+#include "SEQ_modifier.h"
 #include "SEQ_sequencer.h"
 
 #include "readfile.h"
diff --git a/source/blender/blenloader/intern/versioning_250.c b/source/blender/blenloader/intern/versioning_250.c
index b282a978e8a..23f46e15f51 100644
--- a/source/blender/blenloader/intern/versioning_250.c
+++ b/source/blender/blenloader/intern/versioning_250.c
@@ -77,7 +77,7 @@
 #include "BKE_sound.h"
 #include "BKE_texture.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 #include "NOD_socket.h"
 
diff --git a/source/blender/blenloader/intern/versioning_260.c b/source/blender/blenloader/intern/versioning_260.c
index 86085ddbc73..767f24cf175 100644
--- a/source/blender/blenloader/intern/versioning_260.c
+++ b/source/blender/blenloader/intern/versioning_260.c
@@ -67,7 +67,9 @@
 #include "BKE_texture.h"
 #include "BKE_tracking.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
+#include "SEQ_modifier.h"
+#include "SEQ_utils.h"
 
 #ifdef WITH_FFMPEG
 #  include "BKE_writeffmpeg.h"
diff --git a/source/blender/blenloader/intern/versioning_270.c b/source/blender/blenloader/intern/versioning_270.c
index ee5efff7216..df9268f0da1 100644
--- a/source/blender/blenloader/intern/versioning_270.c
+++ b/source/blender/blenloader/intern/versioning_270.c
@@ -66,7 +66,8 @@
 #include "BKE_tracking.h"
 #include "DNA_material_types.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_effects.h"
+#include "SEQ_iterator.h"
 
 #include "BLI_listbase.h"
 #include "BLI_math.h"
diff --git a/source/blender/blenloader/intern/versioning_280.c b/source/blender/blenloader/intern/versioning_280.c
index f7ef7f74a42..88493de5076 100644
--- a/source/blender/blenloader/intern/versioning_280.c
+++ b/source/blender/blenloader/intern/versioning_280.c
@@ -97,7 +97,9 @@
 #include "BKE_unit.h"
 #include "BKE_workspace.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
+#include "SEQ_modifier.h"
+#include "SEQ_utils.h"
 
 /* Only for IMB_BlendMode */
 #include "IMB_imbuf.h"
diff --git a/source/blender/blenloader/intern/versioning_290.c b/source/blender/blenloader/intern/versioning_290.c
index 86293f273b3..b27e62c9218 100644
--- a/source/blender/blenloader/intern/versioning_290.c
+++ b/source/blender/blenloader/intern/versioning_290.c
@@ -66,6 +66,8 @@
 
 #include "RNA_access.h"
 
+#include "SEQ_proxy.h"
+#include "SEQ_render.h"
 #include "SEQ_sequencer.h"
 
 #include "BLO_readfile.h"
diff --git a/source/blender/blenloader/intern/versioning_legacy.c b/source/blender/blenloader/intern/versioning_legacy.c
index 6f459339675..dc8f7a0305a 100644
--- a/source/blender/blenloader/intern/versioning_legacy.c
+++ b/source/blender/blenloader/intern/versioning_legacy.c
@@ -80,7 +80,7 @@
 #include "BKE_particle.h"
 #include "BKE_pointcache.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 #include "NOD_socket.h"
 
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
index e5301532ddc..eb20dfb69a2 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_nodes.cc
@@ -109,7 +109,7 @@
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 #include "intern/builder/deg_builder.h"
 #include "intern/depsgraph.h"
diff --git a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
index de68ec6210e..df48cb91ce7 100644
--- a/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
+++ b/source/blender/depsgraph/intern/builder/deg_builder_relations.cc
@@ -99,7 +99,7 @@
 #include "RNA_access.h"
 #include "RNA_types.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 #include "DEG_depsgraph.h"
 #include "DEG_depsgraph_build.h"
diff --git a/source/blender/depsgraph/intern/eval/deg_eval_copy_on_write.cc b/source/blender/depsgraph/intern/eval/deg_eval_copy_on_write.cc
index 5119de1ed9e..2544bb1642c 100644
--- a/source/blender/depsgraph/intern/eval/deg_eval_copy_on_write.cc
+++ b/source/blender/depsgraph/intern/eval/deg_eval_copy_on_write.cc
@@ -92,7 +92,7 @@
 #include "BKE_pointcache.h"
 #include "BKE_sound.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_relations.h"
 
 #include "intern/builder/deg_builder.h"
 #include "intern/builder/deg_builder_nodes.h"
diff --git a/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup_sequencer.cc b/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup_sequencer.cc
index c0e284a930e..34c23740730 100644
--- a/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup_sequencer.cc
+++ b/source/blender/depsgraph/intern/eval/deg_eval_runtime_backup_sequencer.cc
@@ -30,7 +30,7 @@
 
 #include "BKE_sound.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 namespace blender::deg {
 
diff --git a/source/blender/editors/animation/anim_deps.c b/source/blender/editors/animation/anim_deps.c
index fbd55592729..17251587d3b 100644
--- a/source/blender/editors/animation/anim_deps.c
+++ b/source/blender/editors/animation/anim_deps.c
@@ -50,6 +50,7 @@
 #include "RNA_access.h"
 
 #include "SEQ_sequencer.h"
+#include "SEQ_utils.h"
 
 #include "ED_anim_api.h"
 
diff --git a/source/blender/editors/animation/anim_filter.c b/source/blender/editors/animation/anim_filter.c
index 83665d7a053..f2022194ed5 100644
--- a/source/blender/editors/animation/anim_filter.c
+++ b/source/blender/editors/animation/anim_filter.c
@@ -101,6 +101,7 @@
 #include "ED_markers.h"
 
 #include "SEQ_sequencer.h"
+#include "SEQ_utils.h"
 
 #include "UI_resources.h" /* for TH_KEYFRAME_SCALE lookup */
 
diff --git a/source/blender/editors/animation/anim_ops.c b/source/blender/editors/animation/anim_ops.c
index 07601414fb0..a5514f6517e 100644
--- a/source/blender/editors/animation/anim_ops.c
+++ b/source/blender/editors/animation/anim_ops.c
@@ -56,6 +56,7 @@
 #include "DEG_depsgraph_query.h"
 
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
 
 #include "anim_intern.h"
 
diff --git a/source/blender/editors/render/render_internal.c b/source/blender/editors/render/render_internal.c
index 46680f649cd..10cf4131584 100644
--- a/source/blender/editors/render/render_internal.c
+++ b/source/blender/editors/render/render_internal.c
@@ -83,7 +83,7 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_relations.h"
 
 #include "BLO_undofile.h"
 
diff --git a/source/blender/editors/render/render_opengl.c b/source/blender/editors/render/render_opengl.c
index f7275b06804..1069f942a7a 100644
--- a/source/blender/editors/render/render_opengl.c
+++ b/source/blender/editors/render/render_opengl.c
@@ -77,7 +77,7 @@
 #include "RNA_access.h"
 #include "RNA_define.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_render.h"
 
 #include "GPU_framebuffer.h"
 #include "GPU_matrix.h"
diff --git a/source/blender/editors/sound/sound_ops.c b/source/blender/editors/sound/sound_ops.c
index 5bc13ec1b75..34617804888 100644
--- a/source/blender/editors/sound/sound_ops.c
+++ b/source/blender/editors/sound/sound_ops.c
@@ -52,7 +52,7 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 #include "UI_interface.h"
 
diff --git a/source/blender/editors/space_outliner/outliner_select.c b/source/blender/editors/space_outliner/outliner_select.c
index a1df922b335..6380bb9505e 100644
--- a/source/blender/editors/space_outliner/outliner_select.c
+++ b/source/blender/editors/space_outliner/outliner_select.c
@@ -72,6 +72,7 @@
 #include "ED_sequencer.h"
 #include "ED_undo.h"
 
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
 
 #include "WM_api.h"
diff --git a/source/blender/editors/space_outliner/outliner_sync.c b/source/blender/editors/space_outliner/outliner_sync.c
index b3e8761f60b..0b2d1ce34ec 100644
--- a/source/blender/editors/space_outliner/outliner_sync.c
+++ b/source/blender/editors/space_outliner/outliner_sync.c
@@ -46,7 +46,7 @@
 #include "ED_object.h"
 #include "ED_outliner.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_select.h"
 
 #include "WM_api.h"
 #include "WM_types.h"
diff --git a/source/blender/editors/space_sequencer/sequencer_add.c b/source/blender/editors/space_sequencer/sequencer_add.c
index e40e9f5429d..f9076145f2f 100644
--- a/source/blender/editors/space_sequencer/sequencer_add.c
+++ b/source/blender/editors/space_sequencer/sequencer_add.c
@@ -50,7 +50,15 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
+#include "SEQ_add.h"
+#include "SEQ_effects.h"
+#include "SEQ_relations.h"
+#include "SEQ_render.h"
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
+#include "SEQ_transform.h"
+#include "SEQ_utils.h"
 
 /* For menu, popup, icons, etc. */
 #include "ED_screen.h"
diff --git a/source/blender/editors/space_sequencer/sequencer_draw.c b/source/blender/editors/space_sequencer/sequencer_draw.c
index 2f146690416..1b213746add 100644
--- a/source/blender/editors/space_sequencer/sequencer_draw.c
+++ b/source/blender/editors/space_sequencer/sequencer_draw.c
@@ -68,7 +68,16 @@
 
 #include "BIF_glutil.h"
 
+#include "SEQ_effects.h"
+#include "SEQ_prefetch.h"
+#include "SEQ_proxy.h"
+#include "SEQ_relations.h"
+#include "SEQ_render.h"
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
+#include "SEQ_transform.h"
+#include "SEQ_utils.h"
 
 #include "UI_interface.h"
 #include "UI_resources.h"
diff --git a/source/blender/editors/space_sequencer/sequencer_edit.c b/source/blender/editors/space_sequencer/sequencer_edit.c
index f78b602ceda..c3553ac88ad 100644
--- a/source/blender/editors/space_sequencer/sequencer_edit.c
+++ b/source/blender/editors/space_sequencer/sequencer_edit.c
@@ -45,7 +45,19 @@
 #include "BKE_report.h"
 #include "BKE_sound.h"
 
+#include "SEQ_add.h"
+#include "SEQ_clipboard.h"
+#include "SEQ_edit.h"
+#include "SEQ_effects.h"
+#include "SEQ_iterator.h"
+#include "SEQ_prefetch.h"
+#include "SEQ_relations.h"
+#include "SEQ_render.h"
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
+#include "SEQ_transform.h"
+#include "SEQ_utils.h"
 
 #include "WM_api.h"
 #include "WM_types.h"
diff --git a/source/blender/editors/space_sequencer/sequencer_modifier.c b/source/blender/editors/space_sequencer/sequencer_modifier.c
index e8f4fac1920..f11a879912c 100644
--- a/source/blender/editors/space_sequencer/sequencer_modifier.c
+++ b/source/blender/editors/space_sequencer/sequencer_modifier.c
@@ -34,6 +34,10 @@
 #include "RNA_define.h"
 #include "RNA_enum_types.h"
 
+#include "SEQ_iterator.h"
+#include "SEQ_modifier.h"
+#include "SEQ_relations.h"
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
 
 /* Own include. */
diff --git a/source/blender/editors/space_sequencer/sequencer_proxy.c b/source/blender/editors/space_sequencer/sequencer_proxy.c
index 032885c2719..b04363a4f33 100644
--- a/source/blender/editors/space_sequencer/sequencer_proxy.c
+++ b/source/blender/editors/space_sequencer/sequencer_proxy.c
@@ -34,6 +34,9 @@
 #include "BKE_main.h"
 #include "BKE_report.h"
 
+#include "SEQ_iterator.h"
+#include "SEQ_proxy.h"
+#include "SEQ_relations.h"
 #include "SEQ_sequencer.h"
 
 #include "WM_api.h"
diff --git a/source/blender/editors/space_sequencer/sequencer_select.c b/source/blender/editors/space_sequencer/sequencer_select.c
index 6534a63f03e..a6027a2472c 100644
--- a/source/blender/editors/space_sequencer/sequencer_select.c
+++ b/source/blender/editors/space_sequencer/sequencer_select.c
@@ -39,6 +39,8 @@
 
 #include "RNA_define.h"
 
+#include "SEQ_iterator.h"
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
 
 /* For menu, popup, icons, etc. */
diff --git a/source/blender/editors/space_sequencer/sequencer_view.c b/source/blender/editors/space_sequencer/sequencer_view.c
index 250a0afc717..8805d5af227 100644
--- a/source/blender/editors/space_sequencer/sequencer_view.c
+++ b/source/blender/editors/space_sequencer/sequencer_view.c
@@ -38,7 +38,9 @@
 
 #include "RNA_define.h"
 
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
 
 /* For menu, popup, icons, etc. */
 #include "ED_anim_api.h"
diff --git a/source/blender/editors/space_sequencer/space_sequencer.c b/source/blender/editors/space_sequencer/space_sequencer.c
index 19146db3719..b11e2a32b87 100644
--- a/source/blender/editors/space_sequencer/space_sequencer.c
+++ b/source/blender/editors/space_sequencer/space_sequencer.c
@@ -52,6 +52,7 @@
 #include "RNA_access.h"
 
 #include "SEQ_sequencer.h"
+#include "SEQ_utils.h"
 
 #include "UI_interface.h"
 #include "UI_resources.h"
diff --git a/source/blender/editors/transform/transform_convert_sequencer.c b/source/blender/editors/transform/transform_convert_sequencer.c
index 83e384010bd..ebb0b6823a3 100644
--- a/source/blender/editors/transform/transform_convert_sequencer.c
+++ b/source/blender/editors/transform/transform_convert_sequencer.c
@@ -32,7 +32,11 @@
 
 #include "ED_markers.h"
 
+#include "SEQ_relations.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
+#include "SEQ_transform.h"
+#include "SEQ_utils.h"
 
 #include "UI_view2d.h"
 
diff --git a/source/blender/editors/transform/transform_snap.c b/source/blender/editors/transform/transform_snap.c
index 8d20f1686f2..d407cea0033 100644
--- a/source/blender/editors/transform/transform_snap.c
+++ b/source/blender/editors/transform/transform_snap.c
@@ -42,6 +42,7 @@
 #include "RNA_access.h"
 
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
 
 #include "WM_types.h"
 
diff --git a/source/blender/editors/util/ed_util_imbuf.c b/source/blender/editors/util/ed_util_imbuf.c
index ca97a7b21c3..0f2e280251f 100644
--- a/source/blender/editors/util/ed_util_imbuf.c
+++ b/source/blender/editors/util/ed_util_imbuf.c
@@ -42,6 +42,7 @@
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
 
+#include "SEQ_render.h"
 #include "SEQ_sequencer.h"
 
 #include "UI_view2d.h"
diff --git a/source/blender/imbuf/intern/colormanagement.c b/source/blender/imbuf/intern/colormanagement.c
index 2c95d49612f..046e233fd05 100644
--- a/source/blender/imbuf/intern/colormanagement.c
+++ b/source/blender/imbuf/intern/colormanagement.c
@@ -57,7 +57,7 @@
 
 #include "RNA_define.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 #include <ocio_capi.h>
 
diff --git a/source/blender/makesrna/intern/rna_camera.c b/source/blender/makesrna/intern/rna_camera.c
index 2ac8b50f381..9d0ee90de60 100644
--- a/source/blender/makesrna/intern/rna_camera.c
+++ b/source/blender/makesrna/intern/rna_camera.c
@@ -40,7 +40,7 @@
 #  include "DEG_depsgraph.h"
 #  include "DEG_depsgraph_build.h"
 
-#  include "SEQ_sequencer.h"
+#  include "SEQ_relations.h"
 
 static float rna_Camera_angle_get(PointerRNA *ptr)
 {
diff --git a/source/blender/makesrna/intern/rna_color.c b/source/blender/makesrna/intern/rna_color.c
index 2293b892ddb..39aeeb430c2 100644
--- a/source/blender/makesrna/intern/rna_color.c
+++ b/source/blender/makesrna/intern/rna_color.c
@@ -60,7 +60,8 @@
 #  include "IMB_colormanagement.h"
 #  include "IMB_imbuf.h"
 
-#  include "SEQ_sequencer.h"
+#  include "SEQ_iterator.h"
+#  include "SEQ_relations.h"
 
 static int rna_CurveMapping_curves_length(PointerRNA *ptr)
 {
diff --git a/source/blender/makesrna/intern/rna_movieclip.c b/source/blender/makesrna/intern/rna_movieclip.c
index e7f697b281d..d32872d1682 100644
--- a/source/blender/makesrna/intern/rna_movieclip.c
+++ b/source/blender/makesrna/intern/rna_movieclip.c
@@ -49,7 +49,7 @@
 #  include "DNA_screen_types.h"
 #  include "DNA_space_types.h"
 
-#  include "SEQ_sequencer.h"
+#  include "SEQ_relations.h"
 
 static void rna_MovieClip_reload_update(Main *UNUSED(bmain), Scene *UNUSED(scene), PointerRNA *ptr)
 {
diff --git a/source/blender/makesrna/intern/rna_scene.c b/source/blender/makesrna/intern/rna_scene.c
index bce10b42ea8..b93922e46f2 100644
--- a/source/blender/makesrna/intern/rna_scene.c
+++ b/source/blender/makesrna/intern/rna_scene.c
@@ -699,7 +699,9 @@ const EnumPropertyItem rna_enum_transform_orientation_items[] = {
 #  include "DEG_depsgraph_build.h"
 #  include "DEG_depsgraph_query.h"
 
+#  include "SEQ_relations.h"
 #  include "SEQ_sequencer.h"
+#  include "SEQ_sound.h"
 
 #  ifdef WITH_FREESTYLE
 #    include "FRS_freestyle.h"
diff --git a/source/blender/makesrna/intern/rna_sequencer.c b/source/blender/makesrna/intern/rna_sequencer.c
index 43d65a4380b..4ab32d54665 100644
--- a/source/blender/makesrna/intern/rna_sequencer.c
+++ b/source/blender/makesrna/intern/rna_sequencer.c
@@ -46,7 +46,18 @@
 
 #include "rna_internal.h"
 
+#include "SEQ_add.h"
+#include "SEQ_effects.h"
+#include "SEQ_iterator.h"
+#include "SEQ_modifier.h"
+#include "SEQ_prefetch.h"
+#include "SEQ_proxy.h"
+#include "SEQ_relations.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_sound.h"
+#include "SEQ_time.h"
+#include "SEQ_transform.h"
+#include "SEQ_utils.h"
 
 #include "WM_types.h"
 
diff --git a/source/blender/makesrna/intern/rna_sequencer_api.c b/source/blender/makesrna/intern/rna_sequencer_api.c
index 67497c2da2a..070fb08c3b4 100644
--- a/source/blender/makesrna/intern/rna_sequencer_api.c
+++ b/source/blender/makesrna/intern/rna_sequencer_api.c
@@ -51,6 +51,10 @@
 #  include "IMB_imbuf.h"
 #  include "IMB_imbuf_types.h"
 
+#  include "SEQ_add.h"
+#  include "SEQ_edit.h"
+#  include "SEQ_relations.h"
+#  include "SEQ_render.h"
 #  include "SEQ_sequencer.h"
 
 #  include "WM_api.h"
diff --git a/source/blender/makesrna/intern/rna_space.c b/source/blender/makesrna/intern/rna_space.c
index 5604ccd9655..acfb317c616 100644
--- a/source/blender/makesrna/intern/rna_space.c
+++ b/source/blender/makesrna/intern/rna_space.c
@@ -53,7 +53,7 @@
 
 #include "rna_internal.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_relations.h"
 
 #include "WM_api.h"
 #include "WM_types.h"
diff --git a/source/blender/render/intern/pipeline.c b/source/blender/render/intern/pipeline.c
index fc6ff51976d..f484977d2b4 100644
--- a/source/blender/render/intern/pipeline.c
+++ b/source/blender/render/intern/pipeline.c
@@ -88,7 +88,8 @@
 #include "RE_pipeline.h"
 #include "RE_texture.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_relations.h"
+#include "SEQ_render.h"
 
 #include "../../windowmanager/WM_api.h"    /* XXX */
 #include "../../windowmanager/wm_window.h" /* XXX */
diff --git a/source/blender/sequencer/CMakeLists.txt b/source/blender/sequencer/CMakeLists.txt
index db46fe91718..82e303806b3 100644
--- a/source/blender/sequencer/CMakeLists.txt
+++ b/source/blender/sequencer/CMakeLists.txt
@@ -44,7 +44,22 @@ set(INC_SYS
 )
 
 set(SRC
+  SEQ_add.h
+  SEQ_clipboard.h
+  SEQ_edit.h
+  SEQ_effects.h
+  SEQ_iterator.h
+  SEQ_modifier.h
+  SEQ_prefetch.h
+  SEQ_proxy.h
+  SEQ_relations.h
+  SEQ_render.h
+  SEQ_select.h
   SEQ_sequencer.h
+  SEQ_sound.h
+  SEQ_time.h
+  SEQ_transform.h
+  SEQ_utils.h
 
   intern/clipboard.c
   intern/effects.c
diff --git a/source/blender/sequencer/SEQ_add.h b/source/blender/sequencer/SEQ_add.h
new file mode 100644
index 00000000000..9ed617e6963
--- /dev/null
+++ b/source/blender/sequencer/SEQ_add.h
@@ -0,0 +1,89 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+struct ListBase;
+struct bContext;
+
+/* api for adding new sequence strips */
+typedef struct SeqLoadInfo {
+  int start_frame;
+  int end_frame;
+  int channel;
+  int flag; /* use sound, replace sel */
+  int type;
+  int len;         /* only for image strips */
+  char path[1024]; /* 1024 = FILE_MAX */
+  eSeqImageFitMethod fit_method;
+
+  /* multiview */
+  char views_format;
+  struct Stereo3dFormat *stereo3d_format;
+
+  /* return values */
+  char name[64];
+  struct Sequence *seq_sound; /* for movie's */
+  int tot_success;
+  int tot_error;
+} SeqLoadInfo;
+
+/* SeqLoadInfo.flag */
+#define SEQ_LOAD_REPLACE_SEL (1 << 0)
+#define SEQ_LOAD_FRAME_ADVANCE (1 << 1)
+#define SEQ_LOAD_MOVIE_SOUND (1 << 2)
+#define SEQ_LOAD_SOUND_CACHE (1 << 3)
+#define SEQ_LOAD_SYNC_FPS (1 << 4)
+#define SEQ_LOAD_SOUND_MONO (1 << 5)
+
+/* use as an api function */
+typedef struct Sequence *(*SeqLoadFn)(struct bContext *, ListBase *, struct SeqLoadInfo *);
+
+struct Sequence *SEQ_add_image_strip(struct bContext *C,
+                                     ListBase *seqbasep,
+                                     struct SeqLoadInfo *seq_load);
+struct Sequence *SEQ_add_sound_strip(struct bContext *C,
+                                     ListBase *seqbasep,
+                                     struct SeqLoadInfo *seq_load);
+struct Sequence *SEQ_add_movie_strip(struct bContext *C,
+                                     ListBase *seqbasep,
+                                     struct SeqLoadInfo *seq_load);
+void SEQ_add_reload_new_file(struct Main *bmain,
+                             struct Scene *scene,
+                             struct Sequence *seq,
+                             const bool lock_range);
+void SEQ_add_movie_reload_if_needed(struct Main *bmain,
+                                    struct Scene *scene,
+                                    struct Sequence *seq,
+                                    bool *r_was_reloaded,
+                                    bool *r_can_produce_frames);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_clipboard.h b/source/blender/sequencer/SEQ_clipboard.h
new file mode 100644
index 00000000000..4b2bf69a8ac
--- /dev/null
+++ b/source/blender/sequencer/SEQ_clipboard.h
@@ -0,0 +1,41 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct ListBase;
+struct Main;
+
+extern struct ListBase seqbase_clipboard;
+extern int seqbase_clipboard_frame;
+void SEQ_clipboard_pointers_store(struct Main *bmain, struct ListBase *seqbase);
+void SEQ_clipboard_pointers_restore(struct ListBase *seqbase, struct Main *bmain);
+void SEQ_clipboard_free(void);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_edit.h b/source/blender/sequencer/SEQ_edit.h
new file mode 100644
index 00000000000..b0c5d46d713
--- /dev/null
+++ b/source/blender/sequencer/SEQ_edit.h
@@ -0,0 +1,59 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+struct Main;
+struct ListBase;
+
+int SEQ_edit_sequence_swap(struct Sequence *seq_a, struct Sequence *seq_b, const char **error_str);
+void SEQ_edit_flag_for_removal(struct Scene *scene,
+                               struct ListBase *seqbase,
+                               struct Sequence *seq);
+void SEQ_edit_remove_flagged_sequences(struct Scene *scene, struct ListBase *seqbase);
+void SEQ_edit_update_muting(struct Editing *ed);
+
+typedef enum eSeqSplitMethod {
+  SEQ_SPLIT_SOFT,
+  SEQ_SPLIT_HARD,
+} eSeqSplitMethod;
+
+struct Sequence *SEQ_edit_strip_split(struct Main *bmain,
+                                      struct Scene *scene,
+                                      struct ListBase *seqbase,
+                                      struct Sequence *seq,
+                                      const int timeline_frame,
+                                      const eSeqSplitMethod method);
+bool SEQ_edit_remove_gaps(struct Scene *scene,
+                          struct ListBase *seqbase,
+                          const int initial_frame,
+                          const bool remove_all_gaps);
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_effects.h b/source/blender/sequencer/SEQ_effects.h
new file mode 100644
index 00000000000..1258efd2694
--- /dev/null
+++ b/source/blender/sequencer/SEQ_effects.h
@@ -0,0 +1,118 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Sequence;
+struct ImBuf;
+struct SeqRenderData;
+struct TextVars;
+
+/* Wipe effect */
+enum {
+  DO_SINGLE_WIPE,
+  DO_DOUBLE_WIPE,
+  /* DO_BOX_WIPE, */   /* UNUSED */
+  /* DO_CROSS_WIPE, */ /* UNUSED */
+  DO_IRIS_WIPE,
+  DO_CLOCK_WIPE,
+};
+
+struct SeqEffectHandle {
+  bool multithreaded;
+  bool supports_mask;
+
+  /* constructors & destructor */
+  /* init is _only_ called on first creation */
+  void (*init)(struct Sequence *seq);
+
+  /* number of input strips needed
+   * (called directly after construction) */
+  int (*num_inputs)(void);
+
+  /* load is called first time after readblenfile in
+   * get_sequence_effect automatically */
+  void (*load)(struct Sequence *seqconst);
+
+  /* duplicate */
+  void (*copy)(struct Sequence *dst, struct Sequence *src, const int flag);
+
+  /* destruct */
+  void (*free)(struct Sequence *seq, const bool do_id_user);
+
+  /* returns: -1: no input needed,
+   * 0: no early out,
+   * 1: out = ibuf1,
+   * 2: out = ibuf2 */
+  int (*early_out)(struct Sequence *seq, float facf0, float facf1);
+
+  /* stores the y-range of the effect IPO */
+  void (*store_icu_yrange)(struct Sequence *seq, short adrcode, float *ymin, float *ymax);
+
+  /* stores the default facf0 and facf1 if no IPO is present */
+  void (*get_default_fac)(struct Sequence *seq, float timeline_frame, float *facf0, float *facf1);
+
+  /* execute the effect
+   * sequence effects are only required to either support
+   * float-rects or byte-rects
+   * (mixed cases are handled one layer up...) */
+
+  struct ImBuf *(*execute)(const struct SeqRenderData *context,
+                           struct Sequence *seq,
+                           float timeline_frame,
+                           float facf0,
+                           float facf1,
+                           struct ImBuf *ibuf1,
+                           struct ImBuf *ibuf2,
+                           struct ImBuf *ibuf3);
+
+  struct ImBuf *(*init_execution)(const struct SeqRenderData *context,
+                                  struct ImBuf *ibuf1,
+                                  struct ImBuf *ibuf2,
+                                  struct ImBuf *ibuf3);
+
+  void (*execute_slice)(const struct SeqRenderData *context,
+                        struct Sequence *seq,
+                        float timeline_frame,
+                        float facf0,
+                        float facf1,
+                        struct ImBuf *ibuf1,
+                        struct ImBuf *ibuf2,
+                        struct ImBuf *ibuf3,
+                        int start_line,
+                        int total_lines,
+                        struct ImBuf *out);
+};
+
+struct SeqEffectHandle SEQ_effect_handle_get(struct Sequence *seq);
+int SEQ_effect_get_num_inputs(int seq_type);
+void SEQ_effect_text_font_unload(struct TextVars *data, const bool do_id_user);
+void SEQ_effect_text_font_load(struct TextVars *data, const bool do_id_user);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_iterator.h b/source/blender/sequencer/SEQ_iterator.h
new file mode 100644
index 00000000000..05fd706a8de
--- /dev/null
+++ b/source/blender/sequencer/SEQ_iterator.h
@@ -0,0 +1,75 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Sequence;
+struct Editing;
+
+typedef struct SeqIterator {
+  struct Sequence **array;
+  int tot, cur;
+
+  struct Sequence *seq;
+  int valid;
+} SeqIterator;
+
+#define SEQ_ALL_BEGIN(ed, _seq) \
+  { \
+    SeqIterator iter_macro; \
+    for (SEQ_iterator_begin(ed, &iter_macro, false); iter_macro.valid; \
+         SEQ_iterator_next(&iter_macro)) { \
+      _seq = iter_macro.seq;
+
+#define SEQ_ALL_END \
+  } \
+  SEQ_iterator_end(&iter_macro); \
+  } \
+  ((void)0)
+
+#define SEQ_CURRENT_BEGIN(_ed, _seq) \
+  { \
+    SeqIterator iter_macro; \
+    for (SEQ_iterator_begin(_ed, &iter_macro, true); iter_macro.valid; \
+         SEQ_iterator_next(&iter_macro)) { \
+      _seq = iter_macro.seq;
+
+#define SEQ_CURRENT_END SEQ_ALL_END
+
+void SEQ_iterator_begin(struct Editing *ed, SeqIterator *iter, const bool use_current_sequences);
+void SEQ_iterator_next(SeqIterator *iter);
+void SEQ_iterator_end(SeqIterator *iter);
+int SEQ_iterator_seqbase_recursive_apply(struct ListBase *seqbase,
+                                         int (*apply_fn)(struct Sequence *seq, void *),
+                                         void *arg);
+int SEQ_iterator_recursive_apply(struct Sequence *seq,
+                                 int (*apply_fn)(struct Sequence *, void *),
+                                 void *arg);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_modifier.h b/source/blender/sequencer/SEQ_modifier.h
new file mode 100644
index 00000000000..74948db24d4
--- /dev/null
+++ b/source/blender/sequencer/SEQ_modifier.h
@@ -0,0 +1,88 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+struct ListBase;
+struct SequenceModifierData;
+struct SeqRenderData;
+struct ImBuf;
+struct BlendDataReader;
+struct BlendLibReader;
+struct BlendWriter;
+
+typedef struct SequenceModifierTypeInfo {
+  /* default name for the modifier */
+  char name[64]; /* MAX_NAME */
+
+  /* DNA structure name used on load/save filed */
+  char struct_name[64]; /* MAX_NAME */
+
+  /* size of modifier data structure, used by allocation */
+  int struct_size;
+
+  /* data initialization */
+  void (*init_data)(struct SequenceModifierData *smd);
+
+  /* free data used by modifier,
+   * only modifier-specific data should be freed, modifier descriptor would
+   * be freed outside of this callback
+   */
+  void (*free_data)(struct SequenceModifierData *smd);
+
+  /* copy data from one modifier to another */
+  void (*copy_data)(struct SequenceModifierData *smd, struct SequenceModifierData *target);
+
+  /* apply modifier on a given image buffer */
+  void (*apply)(struct SequenceModifierData *smd, struct ImBuf *ibuf, struct ImBuf *mask);
+} SequenceModifierTypeInfo;
+
+const struct SequenceModifierTypeInfo *SEQ_modifier_type_info_get(int type);
+struct SequenceModifierData *SEQ_modifier_new(struct Sequence *seq, const char *name, int type);
+bool SEQ_modifier_remove(struct Sequence *seq, struct SequenceModifierData *smd);
+void SEQ_modifier_clear(struct Sequence *seq);
+void SEQ_modifier_free(struct SequenceModifierData *smd);
+void SEQ_modifier_unique_name(struct Sequence *seq, struct SequenceModifierData *smd);
+struct SequenceModifierData *SEQ_modifier_find_by_name(struct Sequence *seq, const char *name);
+struct ImBuf *SEQ_modifier_apply_stack(const struct SeqRenderData *context,
+                                       struct Sequence *seq,
+                                       struct ImBuf *ibuf,
+                                       int timeline_frame);
+void SEQ_modifier_list_copy(struct Sequence *seqn, struct Sequence *seq);
+int SEQ_sequence_supports_modifiers(struct Sequence *seq);
+
+void SEQ_modifier_blend_write(struct BlendWriter *writer, struct ListBase *modbase);
+void SEQ_modifier_blend_read_data(struct BlendDataReader *reader, struct ListBase *lb);
+void SEQ_modifier_blend_read_lib(struct BlendLibReader *reader,
+                                 struct Scene *scene,
+                                 struct ListBase *lb);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_prefetch.h b/source/blender/sequencer/SEQ_prefetch.h
new file mode 100644
index 00000000000..2ec8d509a91
--- /dev/null
+++ b/source/blender/sequencer/SEQ_prefetch.h
@@ -0,0 +1,39 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Main;
+
+void SEQ_prefetch_stop_all(void);
+void SEQ_prefetch_stop(struct Scene *scene);
+bool SEQ_prefetch_need_redraw(struct Main *bmain, struct Scene *scene);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_proxy.h b/source/blender/sequencer/SEQ_proxy.h
new file mode 100644
index 00000000000..b909ac7b02d
--- /dev/null
+++ b/source/blender/sequencer/SEQ_proxy.h
@@ -0,0 +1,57 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Main;
+struct GSet;
+struct Sequence;
+struct ListBase;
+struct Depsgraph;
+struct SeqIndexBuildContext;
+struct ListBase;
+
+bool SEQ_proxy_rebuild_context(struct Main *bmain,
+                               struct Depsgraph *depsgraph,
+                               struct Scene *scene,
+                               struct Sequence *seq,
+                               struct GSet *file_list,
+                               struct ListBase *queue);
+void SEQ_proxy_rebuild(struct SeqIndexBuildContext *context,
+                       short *stop,
+                       short *do_update,
+                       float *progress);
+void SEQ_proxy_rebuild_finish(struct SeqIndexBuildContext *context, bool stop);
+void SEQ_proxy_set(struct Sequence *seq, bool value);
+bool SEQ_can_use_proxy(struct Sequence *seq, int psize);
+int SEQ_rendersize_to_proxysize(int render_size);
+double SEQ_rendersize_to_scale_factor(int size);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_relations.h b/source/blender/sequencer/SEQ_relations.h
new file mode 100644
index 00000000000..d0c5d2a474b
--- /dev/null
+++ b/source/blender/sequencer/SEQ_relations.h
@@ -0,0 +1,73 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+struct Main;
+struct ListBase;
+struct ReportList;
+struct MovieClip;
+
+void SEQ_relations_sequence_free_anim(struct Sequence *seq);
+void SEQ_relations_update_changed_seq_and_deps(struct Scene *scene,
+                                               struct Sequence *changed_seq,
+                                               int len_change,
+                                               int ibuf_change);
+bool SEQ_relations_check_scene_recursion(struct Scene *scene, struct ReportList *reports);
+bool SEQ_relations_render_loop_check(struct Sequence *seq_main, struct Sequence *seq);
+void SEQ_relations_free_imbuf(struct Scene *scene, struct ListBase *seqbasep, bool for_render);
+void SEQ_relations_invalidate_cache_raw(struct Scene *scene, struct Sequence *seq);
+void SEQ_relations_invalidate_cache_preprocessed(struct Scene *scene, struct Sequence *seq);
+void SEQ_relations_invalidate_cache_composite(struct Scene *scene, struct Sequence *seq);
+void SEQ_relations_invalidate_dependent(struct Scene *scene, struct Sequence *seq);
+void SEQ_relations_invalidate_scene_strips(struct Main *bmain, struct Scene *scene_target);
+void SEQ_relations_invalidate_movieclip_strips(struct Main *bmain, struct MovieClip *clip_target);
+void SEQ_relations_invalidate_cache_in_range(struct Scene *scene,
+                                             struct Sequence *seq,
+                                             struct Sequence *range_mask,
+                                             int invalidate_types);
+void SEQ_relations_free_all_anim_ibufs(struct Scene *scene, int timeline_frame);
+/* A debug and development function which checks whether sequences have unique UUIDs.
+ * Errors will be reported to the console. */
+void SEQ_relations_check_uuids_unique_and_report(const struct Scene *scene);
+/* Generate new UUID for the given sequence. */
+void SEQ_relations_session_uuid_generate(struct Sequence *sequence);
+
+void SEQ_cache_cleanup(struct Scene *scene);
+void SEQ_cache_iterate(struct Scene *scene,
+                       void *userdata,
+                       bool callback_init(void *userdata, size_t item_count),
+                       bool callback_iter(void *userdata,
+                                          struct Sequence *seq,
+                                          int timeline_frame,
+                                          int cache_type,
+                                          float cost));
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_render.h b/source/blender/sequencer/SEQ_render.h
new file mode 100644
index 00000000000..fea68c14c7b
--- /dev/null
+++ b/source/blender/sequencer/SEQ_render.h
@@ -0,0 +1,88 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Editing;
+struct Sequence;
+struct bSound;
+struct Main;
+struct ListBase;
+
+typedef enum eSeqTaskId {
+  SEQ_TASK_MAIN_RENDER,
+  SEQ_TASK_PREFETCH_RENDER,
+} eSeqTaskId;
+
+typedef struct SeqRenderData {
+  struct Main *bmain;
+  struct Depsgraph *depsgraph;
+  struct Scene *scene;
+  int rectx;
+  int recty;
+  int preview_render_size;
+  int for_render;
+  int motion_blur_samples;
+  float motion_blur_shutter;
+  bool skip_cache;
+  bool is_proxy_render;
+  bool is_prefetch_render;
+  int view_id;
+  /* ID of task for asigning temp cache entries to particular task(thread, etc.) */
+  eSeqTaskId task_id;
+
+  /* special case for OpenGL render */
+  struct GPUOffScreen *gpu_offscreen;
+  // int gpu_samples;
+  // bool gpu_full_samples;
+} SeqRenderData;
+
+struct ImBuf *SEQ_render_give_ibuf(const SeqRenderData *context,
+                                   float timeline_frame,
+                                   int chanshown);
+struct ImBuf *SEQ_render_give_ibuf_direct(const SeqRenderData *context,
+                                          float timeline_frame,
+                                          struct Sequence *seq);
+void SEQ_render_init_colorspace(struct Sequence *seq);
+void SEQ_render_new_render_data(struct Main *bmain,
+                                struct Depsgraph *depsgraph,
+                                struct Scene *scene,
+                                int rectx,
+                                int recty,
+                                int preview_render_size,
+                                int for_render,
+                                SeqRenderData *r_context);
+int SEQ_render_evaluate_frame(struct ListBase *seqbase, int timeline_frame);
+struct StripElem *SEQ_render_give_stripelem(struct Sequence *seq, int timeline_frame);
+
+void SEQ_render_imbuf_from_sequencer_space(struct Scene *scene, struct ImBuf *ibuf);
+void SEQ_render_pixel_from_sequencer_space_v4(struct Scene *scene, float pixel[4]);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_select.h b/source/blender/sequencer/SEQ_select.h
new file mode 100644
index 00000000000..5a65f9c0d8c
--- /dev/null
+++ b/source/blender/sequencer/SEQ_select.h
@@ -0,0 +1,41 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+
+struct Sequence *SEQ_select_active_get(struct Scene *scene);
+int SEQ_select_active_get_pair(struct Scene *scene,
+                               struct Sequence **seq_act,
+                               struct Sequence **seq_other);
+void SEQ_select_active_set(struct Scene *scene, struct Sequence *seq);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_sequencer.h b/source/blender/sequencer/SEQ_sequencer.h
index b2068a0d690..37ad71b64bd 100644
--- a/source/blender/sequencer/SEQ_sequencer.h
+++ b/source/blender/sequencer/SEQ_sequencer.h
@@ -23,15 +23,12 @@
  * \ingroup sequencer
  */
 
-#include "DNA_scene_types.h"
-
 #ifdef __cplusplus
 extern "C" {
 #endif
 
-struct BlendDataReader;
-struct BlendLibReader;
-struct BlendWriter;
+#include "DNA_scene_types.h"
+
 struct Depsgraph;
 struct Editing;
 struct GPUOffScreen;
@@ -54,16 +51,6 @@ struct BlendDataReader;
 struct BlendLibReader;
 struct SequencerToolSettings;
 
-/* Wipe effect */
-enum {
-  DO_SINGLE_WIPE,
-  DO_DOUBLE_WIPE,
-  /* DO_BOX_WIPE, */   /* UNUSED */
-  /* DO_CROSS_WIPE, */ /* UNUSED */
-  DO_IRIS_WIPE,
-  DO_CLOCK_WIPE,
-};
-
 /* RNA enums, just to be more readable */
 enum {
   SEQ_SIDE_MOUSE = -1,
@@ -74,576 +61,39 @@ enum {
   SEQ_SIDE_NO_CHANGE,
 };
 
-/* **********************************************************************
- * sequencer.c
- *
- * Sequencer iterators
- * **********************************************************************
- */
-
-typedef struct SeqIterator {
-  struct Sequence **array;
-  int tot, cur;
-
-  struct Sequence *seq;
-  int valid;
-} SeqIterator;
-
-#define SEQ_ALL_BEGIN(ed, _seq) \
-  { \
-    SeqIterator iter_macro; \
-    for (SEQ_iterator_begin(ed, &iter_macro, false); iter_macro.valid; \
-         SEQ_iterator_next(&iter_macro)) { \
-      _seq = iter_macro.seq;
-
-#define SEQ_ALL_END \
-  } \
-  SEQ_iterator_end(&iter_macro); \
-  } \
-  ((void)0)
-
-#define SEQ_CURRENT_BEGIN(_ed, _seq) \
-  { \
-    SeqIterator iter_macro; \
-    for (SEQ_iterator_begin(_ed, &iter_macro, true); iter_macro.valid; \
-         SEQ_iterator_next(&iter_macro)) { \
-      _seq = iter_macro.seq;
-
-#define SEQ_CURRENT_END SEQ_ALL_END
-
-void SEQ_iterator_begin(struct Editing *ed, SeqIterator *iter, const bool use_current_sequences);
-void SEQ_iterator_next(SeqIterator *iter);
-void SEQ_iterator_end(SeqIterator *iter);
-
-/* **********************************************************************
- * render.c
- *
- * Sequencer render functions
- * **********************************************************************
- */
-
-typedef enum eSeqTaskId {
-  SEQ_TASK_MAIN_RENDER,
-  SEQ_TASK_PREFETCH_RENDER,
-} eSeqTaskId;
-
-typedef struct SeqRenderData {
-  struct Main *bmain;
-  struct Depsgraph *depsgraph;
-  struct Scene *scene;
-  int rectx;
-  int recty;
-  int preview_render_size;
-  int for_render;
-  int motion_blur_samples;
-  float motion_blur_shutter;
-  bool skip_cache;
-  bool is_proxy_render;
-  bool is_prefetch_render;
-  int view_id;
-  /* ID of task for asigning temp cache entries to particular task(thread, etc.) */
-  eSeqTaskId task_id;
-
-  /* special case for OpenGL render */
-  struct GPUOffScreen *gpu_offscreen;
-  // int gpu_samples;
-  // bool gpu_full_samples;
-} SeqRenderData;
-
-struct ImBuf *SEQ_render_give_ibuf(const SeqRenderData *context,
-                                   float timeline_frame,
-                                   int chanshown);
-struct ImBuf *SEQ_render_give_ibuf_direct(const SeqRenderData *context,
-                                          float timeline_frame,
-                                          struct Sequence *seq);
-void SEQ_render_init_colorspace(struct Sequence *seq);
-void SEQ_render_new_render_data(struct Main *bmain,
-                                struct Depsgraph *depsgraph,
-                                struct Scene *scene,
-                                int rectx,
-                                int recty,
-                                int preview_render_size,
-                                int for_render,
-                                SeqRenderData *r_context);
-int SEQ_render_evaluate_frame(struct ListBase *seqbase, int timeline_frame);
-struct StripElem *SEQ_render_give_stripelem(struct Sequence *seq, int timeline_frame);
-
-/* **********************************************************************
- * render.c
- *
- * Sequencer color space functions
- * ********************************************************************** */
-
-void SEQ_render_imbuf_from_sequencer_space(struct Scene *scene, struct ImBuf *ibuf);
-void SEQ_render_pixel_from_sequencer_space_v4(struct Scene *scene, float pixel[4]);
+#define SEQ_CACHE_COST_MAX 10.0f
 
-/* **********************************************************************
- * sequencer.c
- *
- * Sequencer scene functions
- * ********************************************************************** */
+/* seq_dupli' flags */
+#define SEQ_DUPE_UNIQUE_NAME (1 << 0)
+#define SEQ_DUPE_CONTEXT (1 << 1)
+#define SEQ_DUPE_ANIM (1 << 2)
+#define SEQ_DUPE_ALL (1 << 3) /* otherwise only selected are copied */
+#define SEQ_DUPE_IS_RECURSIVE_CALL (1 << 4)
 
 struct SequencerToolSettings *SEQ_tool_settings_init(void);
 void SEQ_tool_settings_free(struct SequencerToolSettings *tool_settings);
 eSeqImageFitMethod SEQ_tool_settings_fit_method_get(struct Scene *scene);
 void SEQ_tool_settings_fit_method_set(struct Scene *scene, eSeqImageFitMethod fit_method);
-
 struct SequencerToolSettings *SEQ_tool_settings_copy(struct SequencerToolSettings *tool_settings);
 struct Editing *SEQ_editing_get(struct Scene *scene, bool alloc);
 struct Editing *SEQ_editing_ensure(struct Scene *scene);
 void SEQ_editing_free(struct Scene *scene, const bool do_id_user);
 struct ListBase *SEQ_active_seqbase_get(const struct Editing *ed);
-void SEQ_sort(struct Scene *scene);
-struct Sequence *SEQ_sequence_from_strip_elem(ListBase *seqbase, struct StripElem *se);
-struct Sequence *SEQ_select_active_get(struct Scene *scene);
-int SEQ_select_active_get_pair(struct Scene *scene,
-                               struct Sequence **seq_act,
-                               struct Sequence **seq_other);
-void SEQ_select_active_set(struct Scene *scene, struct Sequence *seq);
-struct Mask *SEQ_active_mask_get(struct Scene *scene);
-/* apply functions recursively */
-int SEQ_iterator_seqbase_recursive_apply(struct ListBase *seqbase,
-                                         int (*apply_fn)(struct Sequence *seq, void *),
-                                         void *arg);
-int SEQ_iterator_recursive_apply(struct Sequence *seq,
-                                 int (*apply_fn)(struct Sequence *, void *),
-                                 void *arg);
-float SEQ_time_sequence_get_fps(struct Scene *scene, struct Sequence *seq);
-int SEQ_time_find_next_prev_edit(struct Scene *scene,
-                                 int timeline_frame,
-                                 const short side,
-                                 const bool do_skip_mute,
-                                 const bool do_center,
-                                 const bool do_unselected);
-/* maintenance functions, mostly for RNA */
+struct Sequence *SEQ_sequence_alloc(ListBase *lb, int timeline_frame, int machine, int type);
 void SEQ_sequence_free(struct Scene *scene, struct Sequence *seq, const bool do_clean_animdata);
-void SEQ_relations_sequence_free_anim(struct Sequence *seq);
-const char *SEQ_sequence_give_name(struct Sequence *seq);
-ListBase *SEQ_get_seqbase_from_sequence(struct Sequence *seq, int *r_offset);
-void SEQ_time_update_sequence(struct Scene *scene, struct Sequence *seq);
-void SEQ_time_update_sequence_bounds(struct Scene *scene, struct Sequence *seq);
-void SEQ_add_reload_new_file(struct Main *bmain,
-                             struct Scene *scene,
-                             struct Sequence *seq,
-                             const bool lock_range);
-void SEQ_add_movie_reload_if_needed(struct Main *bmain,
-                                    struct Scene *scene,
-                                    struct Sequence *seq,
-                                    bool *r_was_reloaded,
-                                    bool *r_can_produce_frames);
-void SEQ_alpha_mode_from_file_extension(struct Sequence *seq);
-void SEQ_relations_update_changed_seq_and_deps(struct Scene *scene,
-                                               struct Sequence *changed_seq,
-                                               int len_change,
-                                               int ibuf_change);
-bool SEQ_relations_check_scene_recursion(struct Scene *scene, struct ReportList *reports);
-bool SEQ_relations_render_loop_check(struct Sequence *seq_main, struct Sequence *seq);
-int SEQ_time_cmp_time_startdisp(const void *a, const void *b);
-
-/* **********************************************************************
- * proxy.c
- *
- * Proxy functions
- * ********************************************************************** */
-
-bool SEQ_proxy_rebuild_context(struct Main *bmain,
-                               struct Depsgraph *depsgraph,
-                               struct Scene *scene,
-                               struct Sequence *seq,
-                               struct GSet *file_list,
-                               ListBase *queue);
-void SEQ_proxy_rebuild(struct SeqIndexBuildContext *context,
-                       short *stop,
-                       short *do_update,
-                       float *progress);
-void SEQ_proxy_rebuild_finish(struct SeqIndexBuildContext *context, bool stop);
-void SEQ_proxy_set(struct Sequence *seq, bool value);
-bool SEQ_can_use_proxy(struct Sequence *seq, int psize);
-int SEQ_rendersize_to_proxysize(int render_size);
-double SEQ_rendersize_to_scale_factor(int size);
-
-/* **********************************************************************
- * image_cache.c
- *
- * Sequencer memory cache management functions
- * ********************************************************************** */
-
-void SEQ_cache_cleanup(struct Scene *scene);
-void SEQ_cache_iterate(struct Scene *scene,
-                       void *userdata,
-                       bool callback_init(void *userdata, size_t item_count),
-                       bool callback_iter(void *userdata,
-                                          struct Sequence *seq,
-                                          int timeline_frame,
-                                          int cache_type,
-                                          float cost));
-
-/* **********************************************************************
- * prefetch.c
- *
- * Sequencer frame prefetching
- * ********************************************************************** */
-
-#define SEQ_CACHE_COST_MAX 10.0f
-void SEQ_prefetch_stop_all(void);
-void SEQ_prefetch_stop(struct Scene *scene);
-bool SEQ_prefetch_need_redraw(struct Main *bmain, struct Scene *scene);
-
-/* **********************************************************************
- * sequencer.c
- *
- * Sequencer editing functions
- * **********************************************************************
- */
-
-/* for transform but also could use elsewhere */
-int SEQ_transform_get_left_handle_frame(struct Sequence *seq, bool metaclip);
-int SEQ_transform_get_right_handle_frame(struct Sequence *seq, bool metaclip);
-void SEQ_transform_set_left_handle_frame(struct Sequence *seq, int val);
-void SEQ_transform_set_right_handle_frame(struct Sequence *seq, int val);
-void SEQ_transform_handle_xlimits(struct Sequence *seq, int leftflag, int rightflag);
-bool SEQ_transform_sequence_can_be_translated(struct Sequence *seq);
-bool SEQ_transform_single_image_check(struct Sequence *seq);
-void SEQ_transform_fix_single_image_seq_offsets(struct Sequence *seq);
-bool SEQ_transform_test_overlap(struct ListBase *seqbasep, struct Sequence *test);
-void SEQ_transform_translate_sequence(struct Scene *scene, struct Sequence *seq, int delta);
-const struct Sequence *SEQ_get_topmost_sequence(const struct Scene *scene, int frame);
-struct ListBase *SEQ_get_seqbase_by_seq(struct ListBase *seqbase, struct Sequence *seq);
 void SEQ_offset_animdata(struct Scene *scene, struct Sequence *seq, int ofs);
 void SEQ_dupe_animdata(struct Scene *scene, const char *name_src, const char *name_dst);
-bool SEQ_transform_seqbase_shuffle_ex(struct ListBase *seqbasep,
-                                      struct Sequence *test,
-                                      struct Scene *evil_scene,
-                                      int channel_delta);
-bool SEQ_transform_seqbase_shuffle(struct ListBase *seqbasep,
-                                   struct Sequence *test,
-                                   struct Scene *evil_scene);
-bool SEQ_transform_seqbase_shuffle_time(ListBase *seqbasep,
-                                        struct Scene *evil_scene,
-                                        ListBase *markers,
-                                        const bool use_sync_markers);
-bool SEQ_transform_seqbase_isolated_sel_check(struct ListBase *seqbase);
-void SEQ_relations_free_imbuf(struct Scene *scene, struct ListBase *seqbasep, bool for_render);
 struct Sequence *SEQ_sequence_dupli_recursive(const struct Scene *scene_src,
                                               struct Scene *scene_dst,
                                               struct ListBase *new_seq_list,
                                               struct Sequence *seq,
                                               int dupe_flag);
-int SEQ_edit_sequence_swap(struct Sequence *seq_a, struct Sequence *seq_b, const char **error_str);
-void SEQ_sound_update_bounds_all(struct Scene *scene);
-void SEQ_sound_update_bounds(struct Scene *scene, struct Sequence *seq);
-void SEQ_sound_update_muting(struct Editing *ed);
-void SEQ_sound_update(struct Scene *scene, struct bSound *sound);
-void SEQ_sound_update_length(struct Main *bmain, struct Scene *scene);
-void SEQ_sequence_base_unique_name_recursive(ListBase *seqbasep, struct Sequence *seq);
 void SEQ_sequence_base_dupli_recursive(const struct Scene *scene_src,
                                        struct Scene *scene_dst,
                                        struct ListBase *nseqbase,
                                        const struct ListBase *seqbase,
                                        int dupe_flag,
                                        const int flag);
-bool SEQ_sequence_has_source(struct Sequence *seq);
-struct Sequence *SEQ_get_sequence_by_name(struct ListBase *seqbase,
-                                          const char *name,
-                                          bool recursive);
-void SEQ_edit_flag_for_removal(struct Scene *scene,
-                               struct ListBase *seqbase,
-                               struct Sequence *seq);
-void SEQ_edit_remove_flagged_sequences(struct Scene *scene, struct ListBase *seqbase);
-
-/* **********************************************************************
- * sequencer.c
- *
- * Cache invalidation
- * **********************************************************************
- */
-
-void SEQ_relations_invalidate_cache_raw(struct Scene *scene, struct Sequence *seq);
-void SEQ_relations_invalidate_cache_preprocessed(struct Scene *scene, struct Sequence *seq);
-void SEQ_relations_invalidate_cache_composite(struct Scene *scene, struct Sequence *seq);
-void SEQ_relations_invalidate_dependent(struct Scene *scene, struct Sequence *seq);
-void SEQ_relations_invalidate_scene_strips(struct Main *bmain, struct Scene *scene_target);
-void SEQ_relations_invalidate_movieclip_strips(struct Main *bmain, struct MovieClip *clip_target);
-void SEQ_relations_invalidate_cache_in_range(struct Scene *scene,
-                                             struct Sequence *seq,
-                                             struct Sequence *range_mask,
-                                             int invalidate_types);
-void SEQ_relations_free_all_anim_ibufs(struct Scene *scene, int timeline_frame);
-
-/* **********************************************************************
- * util.c
- *
- * Add strips
- * **********************************************************************
- */
-
-void SEQ_set_scale_to_fit(const struct Sequence *seq,
-                          const int image_width,
-                          const int image_height,
-                          const int preview_width,
-                          const int preview_height,
-                          const eSeqImageFitMethod fit_method);
-
-/* **********************************************************************
- * sequencer.c
- *
- * Add strips
- * **********************************************************************
- */
-
-/* api for adding new sequence strips */
-typedef struct SeqLoadInfo {
-  int start_frame;
-  int end_frame;
-  int channel;
-  int flag; /* use sound, replace sel */
-  int type;
-  int len;         /* only for image strips */
-  char path[1024]; /* 1024 = FILE_MAX */
-  eSeqImageFitMethod fit_method;
-
-  /* multiview */
-  char views_format;
-  struct Stereo3dFormat *stereo3d_format;
-
-  /* return values */
-  char name[64];
-  struct Sequence *seq_sound; /* for movie's */
-  int tot_success;
-  int tot_error;
-} SeqLoadInfo;
-
-/* SeqLoadInfo.flag */
-#define SEQ_LOAD_REPLACE_SEL (1 << 0)
-#define SEQ_LOAD_FRAME_ADVANCE (1 << 1)
-#define SEQ_LOAD_MOVIE_SOUND (1 << 2)
-#define SEQ_LOAD_SOUND_CACHE (1 << 3)
-#define SEQ_LOAD_SYNC_FPS (1 << 4)
-#define SEQ_LOAD_SOUND_MONO (1 << 5)
-
-/* seq_dupli' flags */
-#define SEQ_DUPE_UNIQUE_NAME (1 << 0)
-#define SEQ_DUPE_CONTEXT (1 << 1)
-#define SEQ_DUPE_ANIM (1 << 2)
-#define SEQ_DUPE_ALL (1 << 3) /* otherwise only selected are copied */
-#define SEQ_DUPE_IS_RECURSIVE_CALL (1 << 4)
-
-/* use as an api function */
-typedef struct Sequence *(*SeqLoadFn)(struct bContext *, ListBase *, struct SeqLoadInfo *);
-
-struct Sequence *SEQ_sequence_alloc(ListBase *lb, int timeline_frame, int machine, int type);
-struct Sequence *SEQ_add_image_strip(struct bContext *C,
-                                     ListBase *seqbasep,
-                                     struct SeqLoadInfo *seq_load);
-struct Sequence *SEQ_add_sound_strip(struct bContext *C,
-                                     ListBase *seqbasep,
-                                     struct SeqLoadInfo *seq_load);
-struct Sequence *SEQ_add_movie_strip(struct bContext *C,
-                                     ListBase *seqbasep,
-                                     struct SeqLoadInfo *seq_load);
-
-/* **********************************************************************
- * modifier.c
- *
- * Modifiers
- * **********************************************************************
- */
-
-typedef struct SequenceModifierTypeInfo {
-  /* default name for the modifier */
-  char name[64]; /* MAX_NAME */
-
-  /* DNA structure name used on load/save filed */
-  char struct_name[64]; /* MAX_NAME */
-
-  /* size of modifier data structure, used by allocation */
-  int struct_size;
-
-  /* data initialization */
-  void (*init_data)(struct SequenceModifierData *smd);
-
-  /* free data used by modifier,
-   * only modifier-specific data should be freed, modifier descriptor would
-   * be freed outside of this callback
-   */
-  void (*free_data)(struct SequenceModifierData *smd);
-
-  /* copy data from one modifier to another */
-  void (*copy_data)(struct SequenceModifierData *smd, struct SequenceModifierData *target);
-
-  /* apply modifier on a given image buffer */
-  void (*apply)(struct SequenceModifierData *smd, struct ImBuf *ibuf, struct ImBuf *mask);
-} SequenceModifierTypeInfo;
-
-const struct SequenceModifierTypeInfo *SEQ_modifier_type_info_get(int type);
-struct SequenceModifierData *SEQ_modifier_new(struct Sequence *seq, const char *name, int type);
-bool SEQ_modifier_remove(struct Sequence *seq, struct SequenceModifierData *smd);
-void SEQ_modifier_clear(struct Sequence *seq);
-void SEQ_modifier_free(struct SequenceModifierData *smd);
-void SEQ_modifier_unique_name(struct Sequence *seq, struct SequenceModifierData *smd);
-struct SequenceModifierData *SEQ_modifier_find_by_name(struct Sequence *seq, const char *name);
-struct ImBuf *SEQ_modifier_apply_stack(const SeqRenderData *context,
-                                       struct Sequence *seq,
-                                       struct ImBuf *ibuf,
-                                       int timeline_frame);
-void SEQ_modifier_list_copy(struct Sequence *seqn, struct Sequence *seq);
-int SEQ_sequence_supports_modifiers(struct Sequence *seq);
-
-void SEQ_modifier_blend_write(struct BlendWriter *writer, struct ListBase *modbase);
-void SEQ_modifier_blend_read_data(struct BlendDataReader *reader, struct ListBase *lb);
-void SEQ_modifier_blend_read_lib(struct BlendLibReader *reader,
-                                 struct Scene *scene,
-                                 struct ListBase *lb);
-
-/* **********************************************************************
- * seqeffects.c
- *
- * Sequencer effect strip management functions
- *  **********************************************************************
- */
-
-struct SeqEffectHandle {
-  bool multithreaded;
-  bool supports_mask;
-
-  /* constructors & destructor */
-  /* init is _only_ called on first creation */
-  void (*init)(struct Sequence *seq);
-
-  /* number of input strips needed
-   * (called directly after construction) */
-  int (*num_inputs)(void);
-
-  /* load is called first time after readblenfile in
-   * get_sequence_effect automatically */
-  void (*load)(struct Sequence *seqconst);
-
-  /* duplicate */
-  void (*copy)(struct Sequence *dst, struct Sequence *src, const int flag);
-
-  /* destruct */
-  void (*free)(struct Sequence *seq, const bool do_id_user);
-
-  /* returns: -1: no input needed,
-   * 0: no early out,
-   * 1: out = ibuf1,
-   * 2: out = ibuf2 */
-  int (*early_out)(struct Sequence *seq, float facf0, float facf1);
-
-  /* stores the y-range of the effect IPO */
-  void (*store_icu_yrange)(struct Sequence *seq, short adrcode, float *ymin, float *ymax);
-
-  /* stores the default facf0 and facf1 if no IPO is present */
-  void (*get_default_fac)(struct Sequence *seq, float timeline_frame, float *facf0, float *facf1);
-
-  /* execute the effect
-   * sequence effects are only required to either support
-   * float-rects or byte-rects
-   * (mixed cases are handled one layer up...) */
-
-  struct ImBuf *(*execute)(const SeqRenderData *context,
-                           struct Sequence *seq,
-                           float timeline_frame,
-                           float facf0,
-                           float facf1,
-                           struct ImBuf *ibuf1,
-                           struct ImBuf *ibuf2,
-                           struct ImBuf *ibuf3);
-
-  struct ImBuf *(*init_execution)(const SeqRenderData *context,
-                                  struct ImBuf *ibuf1,
-                                  struct ImBuf *ibuf2,
-                                  struct ImBuf *ibuf3);
-
-  void (*execute_slice)(const SeqRenderData *context,
-                        struct Sequence *seq,
-                        float timeline_frame,
-                        float facf0,
-                        float facf1,
-                        struct ImBuf *ibuf1,
-                        struct ImBuf *ibuf2,
-                        struct ImBuf *ibuf3,
-                        int start_line,
-                        int total_lines,
-                        struct ImBuf *out);
-};
-
-struct SeqEffectHandle SEQ_effect_handle_get(struct Sequence *seq);
-int SEQ_effect_get_num_inputs(int seq_type);
-void SEQ_effect_text_font_unload(struct TextVars *data, const bool do_id_user);
-void SEQ_effect_text_font_load(struct TextVars *data, const bool do_id_user);
-
-/* **********************************************************************
- * sequencer.c
- *
- * Clipboard
- * **********************************************************************
- */
-
-extern ListBase seqbase_clipboard;
-extern int seqbase_clipboard_frame;
-void SEQ_clipboard_pointers_store(struct Main *bmain, struct ListBase *seqbase);
-void SEQ_clipboard_pointers_restore(struct ListBase *seqbase, struct Main *bmain);
-void SEQ_clipboard_free(void);
-
-/* **********************************************************************
- * sequencer.c
- *
- * Depsgraph
- * **********************************************************************
- */
-
-/* A debug and development function which checks whether sequences have unique UUIDs.
- * Errors will be reported to the console. */
-void SEQ_relations_check_uuids_unique_and_report(const struct Scene *scene);
-/* Generate new UUID for the given sequence. */
-void SEQ_relations_session_uuid_generate(struct Sequence *sequence);
-
-/* **********************************************************************
- * strip_edit.c
- *
- * Editing functions
- * **********************************************************************
- */
-
-typedef enum eSeqSplitMethod {
-  SEQ_SPLIT_SOFT,
-  SEQ_SPLIT_HARD,
-} eSeqSplitMethod;
-
-struct Sequence *SEQ_edit_strip_split(struct Main *bmain,
-                                      struct Scene *scene,
-                                      struct ListBase *seqbase,
-                                      struct Sequence *seq,
-                                      const int timeline_frame,
-                                      const eSeqSplitMethod method);
-bool SEQ_edit_remove_gaps(struct Scene *scene,
-                          struct ListBase *seqbase,
-                          const int initial_frame,
-                          const bool remove_all_gaps);
-
-/* **********************************************************************
- * strip_time.c
- *
- * Editing functions
- * **********************************************************************
- */
-
-void SEQ_timeline_boundbox(const struct Scene *scene,
-                           const struct ListBase *seqbase,
-                           struct rctf *rect);
-
-/* **********************************************************************
- * strip_transform.c
- *
- * Editing functions
- * **********************************************************************
- */
-
-void SEQ_transform_offset_after_frame(struct Scene *scene,
-                                      struct ListBase *seqbase,
-                                      const int delta,
-                                      const int timeline_frame);
 
 #ifdef __cplusplus
 }
diff --git a/source/blender/sequencer/SEQ_sound.h b/source/blender/sequencer/SEQ_sound.h
new file mode 100644
index 00000000000..d04aed259fb
--- /dev/null
+++ b/source/blender/sequencer/SEQ_sound.h
@@ -0,0 +1,44 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Editing;
+struct Sequence;
+struct bSound;
+struct Main;
+struct ListBase;
+
+void SEQ_sound_update_bounds_all(struct Scene *scene);
+void SEQ_sound_update_bounds(struct Scene *scene, struct Sequence *seq);
+void SEQ_sound_update(struct Scene *scene, struct bSound *sound);
+void SEQ_sound_update_length(struct Main *bmain, struct Scene *scene);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_time.h b/source/blender/sequencer/SEQ_time.h
new file mode 100644
index 00000000000..7fb47d42354
--- /dev/null
+++ b/source/blender/sequencer/SEQ_time.h
@@ -0,0 +1,51 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+struct ListBase;
+struct rctf;
+
+void SEQ_timeline_boundbox(const struct Scene *scene,
+                           const struct ListBase *seqbase,
+                           struct rctf *rect);
+float SEQ_time_sequence_get_fps(struct Scene *scene, struct Sequence *seq);
+int SEQ_time_find_next_prev_edit(struct Scene *scene,
+                                 int timeline_frame,
+                                 const short side,
+                                 const bool do_skip_mute,
+                                 const bool do_center,
+                                 const bool do_unselected);
+void SEQ_time_update_sequence(struct Scene *scene, struct Sequence *seq);
+void SEQ_time_update_sequence_bounds(struct Scene *scene, struct Sequence *seq);
+int SEQ_time_cmp_time_startdisp(const void *a, const void *b);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_transform.h b/source/blender/sequencer/SEQ_transform.h
new file mode 100644
index 00000000000..10d9c781dcb
--- /dev/null
+++ b/source/blender/sequencer/SEQ_transform.h
@@ -0,0 +1,63 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+struct ListBase;
+
+int SEQ_transform_get_left_handle_frame(struct Sequence *seq, bool metaclip);
+int SEQ_transform_get_right_handle_frame(struct Sequence *seq, bool metaclip);
+void SEQ_transform_set_left_handle_frame(struct Sequence *seq, int val);
+void SEQ_transform_set_right_handle_frame(struct Sequence *seq, int val);
+void SEQ_transform_handle_xlimits(struct Sequence *seq, int leftflag, int rightflag);
+bool SEQ_transform_sequence_can_be_translated(struct Sequence *seq);
+bool SEQ_transform_single_image_check(struct Sequence *seq);
+void SEQ_transform_fix_single_image_seq_offsets(struct Sequence *seq);
+bool SEQ_transform_test_overlap(struct ListBase *seqbasep, struct Sequence *test);
+void SEQ_transform_translate_sequence(struct Scene *scene, struct Sequence *seq, int delta);
+bool SEQ_transform_seqbase_shuffle_ex(struct ListBase *seqbasep,
+                                      struct Sequence *test,
+                                      struct Scene *evil_scene,
+                                      int channel_delta);
+bool SEQ_transform_seqbase_shuffle(struct ListBase *seqbasep,
+                                   struct Sequence *test,
+                                   struct Scene *evil_scene);
+bool SEQ_transform_seqbase_shuffle_time(struct ListBase *seqbasep,
+                                        struct Scene *evil_scene,
+                                        struct ListBase *markers,
+                                        const bool use_sync_markers);
+bool SEQ_transform_seqbase_isolated_sel_check(struct ListBase *seqbase);
+void SEQ_transform_offset_after_frame(struct Scene *scene,
+                                      struct ListBase *seqbase,
+                                      const int delta,
+                                      const int timeline_frame);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_util.h b/source/blender/sequencer/SEQ_util.h
new file mode 100644
index 00000000000..9dae0a25a37
--- /dev/null
+++ b/source/blender/sequencer/SEQ_util.h
@@ -0,0 +1,58 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#include "DNA_scene_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+struct ListBase;
+
+void SEQ_set_scale_to_fit(const struct Sequence *seq,
+                          const int image_width,
+                          const int image_height,
+                          const int preview_width,
+                          const int preview_height,
+                          const eSeqImageFitMethod fit_method);
+void SEQ_sort(struct Scene *scene);
+void SEQ_sequence_base_unique_name_recursive(ListBase *seqbasep, struct Sequence *seq);
+const char *SEQ_sequence_give_name(struct Sequence *seq);
+ListBase *SEQ_get_seqbase_from_sequence(struct Sequence *seq, int *r_offset);
+const struct Sequence *SEQ_get_topmost_sequence(const struct Scene *scene, int frame);
+struct ListBase *SEQ_get_seqbase_by_seq(struct ListBase *seqbase, struct Sequence *seq);
+struct Sequence *SEQ_sequence_from_strip_elem(ListBase *seqbase, struct StripElem *se);
+struct Sequence *SEQ_get_sequence_by_name(struct ListBase *seqbase,
+                                          const char *name,
+                                          bool recursive);
+struct Mask *SEQ_active_mask_get(struct Scene *scene);
+void SEQ_alpha_mode_from_file_extension(struct Sequence *seq);
+bool SEQ_sequence_has_source(struct Sequence *seq);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/SEQ_utils.h b/source/blender/sequencer/SEQ_utils.h
new file mode 100644
index 00000000000..417d257ddd7
--- /dev/null
+++ b/source/blender/sequencer/SEQ_utils.h
@@ -0,0 +1,60 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2004 Blender Foundation.
+ * All rights reserved.
+ */
+
+#pragma once
+
+/** \file
+ * \ingroup sequencer
+ */
+
+#include "DNA_scene_types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct Scene;
+struct Sequence;
+struct ListBase;
+struct Mask;
+struct StripElem;
+
+void SEQ_sort(struct Scene *scene);
+void SEQ_sequence_base_unique_name_recursive(struct ListBase *seqbasep, struct Sequence *seq);
+const char *SEQ_sequence_give_name(struct Sequence *seq);
+struct ListBase *SEQ_get_seqbase_from_sequence(struct Sequence *seq, int *r_offset);
+const struct Sequence *SEQ_get_topmost_sequence(const struct Scene *scene, int frame);
+struct ListBase *SEQ_get_seqbase_by_seq(struct ListBase *seqbase, struct Sequence *seq);
+struct Sequence *SEQ_sequence_from_strip_elem(struct ListBase *seqbase, struct StripElem *se);
+struct Sequence *SEQ_get_sequence_by_name(struct ListBase *seqbase,
+                                          const char *name,
+                                          bool recursive);
+struct Mask *SEQ_active_mask_get(struct Scene *scene);
+void SEQ_alpha_mode_from_file_extension(struct Sequence *seq);
+bool SEQ_sequence_has_source(struct Sequence *seq);
+void SEQ_set_scale_to_fit(const struct Sequence *seq,
+                          const int image_width,
+                          const int image_height,
+                          const int preview_width,
+                          const int preview_height,
+                          const eSeqImageFitMethod fit_method);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/source/blender/sequencer/intern/clipboard.c b/source/blender/sequencer/intern/clipboard.c
index 7a9a06a744a..29cb749bc99 100644
--- a/source/blender/sequencer/intern/clipboard.c
+++ b/source/blender/sequencer/intern/clipboard.c
@@ -37,7 +37,7 @@
 #include "BKE_scene.h"
 #include "BKE_sound.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_clipboard.h"
 
 #include "sequencer.h"
 
diff --git a/source/blender/sequencer/intern/effects.c b/source/blender/sequencer/intern/effects.c
index 58dd6d6e048..e8e80c8da83 100644
--- a/source/blender/sequencer/intern/effects.c
+++ b/source/blender/sequencer/intern/effects.c
@@ -59,7 +59,10 @@
 
 #include "RE_pipeline.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_effects.h"
+#include "SEQ_proxy.h"
+#include "SEQ_render.h"
+#include "SEQ_utils.h"
 
 #include "BLF_api.h"
 
diff --git a/source/blender/sequencer/intern/image_cache.c b/source/blender/sequencer/intern/image_cache.c
index 6eb12df7186..2fe59f52bf4 100644
--- a/source/blender/sequencer/intern/image_cache.c
+++ b/source/blender/sequencer/intern/image_cache.c
@@ -48,6 +48,9 @@
 #include "BKE_main.h"
 #include "BKE_scene.h"
 
+#include "SEQ_prefetch.h"
+#include "SEQ_relations.h"
+#include "SEQ_render.h"
 #include "SEQ_sequencer.h"
 
 #include "image_cache.h"
diff --git a/source/blender/sequencer/intern/iterator.c b/source/blender/sequencer/intern/iterator.c
index 7d54795b150..bb4982d1468 100644
--- a/source/blender/sequencer/intern/iterator.c
+++ b/source/blender/sequencer/intern/iterator.c
@@ -35,7 +35,7 @@
 
 #include "BKE_scene.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_iterator.h"
 
 /* ************************* iterator ************************** */
 /* *************** (replaces old WHILE_SEQ) ********************* */
diff --git a/source/blender/sequencer/intern/modifier.c b/source/blender/sequencer/intern/modifier.c
index 99fa228e7a5..b6f56025e6b 100644
--- a/source/blender/sequencer/intern/modifier.c
+++ b/source/blender/sequencer/intern/modifier.c
@@ -44,7 +44,8 @@
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_modifier.h"
+#include "SEQ_render.h"
 
 #include "BLO_read_write.h"
 
diff --git a/source/blender/sequencer/intern/prefetch.c b/source/blender/sequencer/intern/prefetch.c
index 5d769a18a19..5ffb2287e1c 100644
--- a/source/blender/sequencer/intern/prefetch.c
+++ b/source/blender/sequencer/intern/prefetch.c
@@ -53,7 +53,8 @@
 #include "DEG_depsgraph_debug.h"
 #include "DEG_depsgraph_query.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_prefetch.h"
+#include "SEQ_render.h"
 
 #include "image_cache.h"
 #include "prefetch.h"
diff --git a/source/blender/sequencer/intern/proxy.c b/source/blender/sequencer/intern/proxy.c
index 72dc9708ccb..22d8daba696 100644
--- a/source/blender/sequencer/intern/proxy.c
+++ b/source/blender/sequencer/intern/proxy.c
@@ -54,6 +54,8 @@
 #include "IMB_imbuf_types.h"
 #include "IMB_metadata.h"
 
+#include "SEQ_proxy.h"
+#include "SEQ_render.h"
 #include "SEQ_sequencer.h"
 
 #include "multiview.h"
diff --git a/source/blender/sequencer/intern/render.c b/source/blender/sequencer/intern/render.c
index 84f2a6df647..524bf7cd74c 100644
--- a/source/blender/sequencer/intern/render.c
+++ b/source/blender/sequencer/intern/render.c
@@ -64,7 +64,12 @@
 #include "RE_engine.h"
 #include "RE_pipeline.h"
 
+#include "SEQ_effects.h"
+#include "SEQ_modifier.h"
+#include "SEQ_proxy.h"
+#include "SEQ_render.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_utils.h"
 
 #include "effects.h"
 #include "image_cache.h"
diff --git a/source/blender/sequencer/intern/render.h b/source/blender/sequencer/intern/render.h
index 46748415187..6875087df82 100644
--- a/source/blender/sequencer/intern/render.h
+++ b/source/blender/sequencer/intern/render.h
@@ -32,6 +32,7 @@ struct ListBase;
 struct Scene;
 struct SeqRenderData;
 struct Sequence;
+struct SeqEffectHandle;
 
 #define EARLY_NO_INPUT -1
 #define EARLY_DO_EFFECT 0
@@ -50,7 +51,7 @@ struct ImBuf *seq_render_give_ibuf_seqbase(const struct SeqRenderData *context,
                                            int chan_shown,
                                            struct ListBase *seqbasep);
 struct ImBuf *seq_render_effect_execute_threaded(struct SeqEffectHandle *sh,
-                                                 const SeqRenderData *context,
+                                                 const struct SeqRenderData *context,
                                                  struct Sequence *seq,
                                                  float timeline_frame,
                                                  float facf0,
diff --git a/source/blender/sequencer/intern/sequencer.c b/source/blender/sequencer/intern/sequencer.c
index 51495e7bf02..79e8ba2f6c0 100644
--- a/source/blender/sequencer/intern/sequencer.c
+++ b/source/blender/sequencer/intern/sequencer.c
@@ -44,7 +44,13 @@
 #include "IMB_colormanagement.h"
 #include "IMB_imbuf.h"
 
+#include "SEQ_effects.h"
+#include "SEQ_iterator.h"
+#include "SEQ_modifier.h"
+#include "SEQ_relations.h"
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_utils.h"
 
 #include "image_cache.h"
 #include "prefetch.h"
diff --git a/source/blender/sequencer/intern/sound.c b/source/blender/sequencer/intern/sound.c
index f62142d0112..1054dbeeba6 100644
--- a/source/blender/sequencer/intern/sound.c
+++ b/source/blender/sequencer/intern/sound.c
@@ -36,28 +36,11 @@
 #include "BKE_scene.h"
 #include "BKE_sound.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_sound.h"
+#include "SEQ_time.h"
 
 #include "strip_time.h"
 
-static void seq_sound_init(Scene *scene, Sequence *seq)
-{
-  if (seq->type == SEQ_TYPE_META) {
-    Sequence *seq_child;
-    for (seq_child = seq->seqbase.first; seq_child; seq_child = seq_child->next) {
-      seq_sound_init(scene, seq_child);
-    }
-  }
-  else {
-    if (seq->sound) {
-      seq->scene_sound = BKE_sound_add_scene_sound_defaults(scene, seq);
-    }
-    if (seq->scene) {
-      seq->scene_sound = BKE_sound_scene_add_scene_sound_defaults(scene, seq);
-    }
-  }
-}
-
 /* Unlike _update_sound_ funcs, these ones take info from audaspace to update sequence length! */
 #ifdef WITH_AUDASPACE
 static bool sequencer_refresh_sound_length_recursive(Main *bmain, Scene *scene, ListBase *seqbase)
diff --git a/source/blender/sequencer/intern/strip_add.c b/source/blender/sequencer/intern/strip_add.c
index 4fe02b7fdd2..ba080a07879 100644
--- a/source/blender/sequencer/intern/strip_add.c
+++ b/source/blender/sequencer/intern/strip_add.c
@@ -53,7 +53,13 @@
 #include "IMB_imbuf_types.h"
 #include "IMB_metadata.h"
 
+#include "SEQ_add.h"
+#include "SEQ_relations.h"
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
+#include "SEQ_transform.h"
+#include "SEQ_utils.h"
 
 #include "multiview.h"
 #include "proxy.h"
diff --git a/source/blender/sequencer/intern/strip_edit.c b/source/blender/sequencer/intern/strip_edit.c
index 11f42c5de9d..bba026057d2 100644
--- a/source/blender/sequencer/intern/strip_edit.c
+++ b/source/blender/sequencer/intern/strip_edit.c
@@ -40,7 +40,12 @@
 
 #include "strip_time.h"
 
+#include "SEQ_add.h"
+#include "SEQ_edit.h"
+#include "SEQ_effects.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
+#include "SEQ_transform.h"
 
 int SEQ_edit_sequence_swap(Sequence *seq_a, Sequence *seq_b, const char **error_str)
 {
@@ -124,7 +129,7 @@ static void seq_update_muting_recursive(ListBase *seqbasep, Sequence *metaseq, i
   }
 }
 
-void SEQ_sound_update_muting(Editing *ed)
+void SEQ_edit_update_muting(Editing *ed)
 {
   if (ed) {
     /* mute all sounds up to current metastack list */
diff --git a/source/blender/sequencer/intern/strip_relations.c b/source/blender/sequencer/intern/strip_relations.c
index 939cafb09fd..18ae21e3a65 100644
--- a/source/blender/sequencer/intern/strip_relations.c
+++ b/source/blender/sequencer/intern/strip_relations.c
@@ -40,7 +40,11 @@
 
 #include "IMB_imbuf.h"
 
+#include "SEQ_iterator.h"
+#include "SEQ_prefetch.h"
+#include "SEQ_relations.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
 
 #include "effects.h"
 #include "image_cache.h"
diff --git a/source/blender/sequencer/intern/strip_select.c b/source/blender/sequencer/intern/strip_select.c
index fbf28087825..58ae281ead1 100644
--- a/source/blender/sequencer/intern/strip_select.c
+++ b/source/blender/sequencer/intern/strip_select.c
@@ -29,6 +29,7 @@
 
 #include "BKE_scene.h"
 
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
 
 Sequence *SEQ_select_active_get(Scene *scene)
diff --git a/source/blender/sequencer/intern/strip_time.c b/source/blender/sequencer/intern/strip_time.c
index a3b17a7c58c..c495ad6d8f1 100644
--- a/source/blender/sequencer/intern/strip_time.c
+++ b/source/blender/sequencer/intern/strip_time.c
@@ -36,7 +36,9 @@
 
 #include "IMB_imbuf.h"
 
+#include "SEQ_render.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
 
 #include "strip_time.h"
 #include "utils.h"
diff --git a/source/blender/sequencer/intern/strip_transform.c b/source/blender/sequencer/intern/strip_transform.c
index 0cf3940dc54..3a0ba36b795 100644
--- a/source/blender/sequencer/intern/strip_transform.c
+++ b/source/blender/sequencer/intern/strip_transform.c
@@ -33,7 +33,11 @@
 #include "BKE_scene.h"
 #include "BKE_sound.h"
 
+#include "SEQ_effects.h"
+#include "SEQ_relations.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_time.h"
+#include "SEQ_transform.h"
 
 static int seq_tx_get_start(Sequence *seq)
 {
diff --git a/source/blender/sequencer/intern/utils.c b/source/blender/sequencer/intern/utils.c
index 40f2aca4714..a15465eb3c0 100644
--- a/source/blender/sequencer/intern/utils.c
+++ b/source/blender/sequencer/intern/utils.c
@@ -42,7 +42,11 @@
 #include "BKE_main.h"
 #include "BKE_scene.h"
 
+#include "SEQ_iterator.h"
+#include "SEQ_relations.h"
+#include "SEQ_select.h"
 #include "SEQ_sequencer.h"
+#include "SEQ_utils.h"
 
 #include "IMB_imbuf.h"
 #include "IMB_imbuf_types.h"
diff --git a/source/blender/windowmanager/intern/wm_init_exit.c b/source/blender/windowmanager/intern/wm_init_exit.c
index be58575f99c..d513598cf19 100644
--- a/source/blender/windowmanager/intern/wm_init_exit.c
+++ b/source/blender/windowmanager/intern/wm_init_exit.c
@@ -80,7 +80,7 @@
 #include "RE_engine.h"
 #include "RE_pipeline.h" /* RE_ free stuff */
 
-#include "SEQ_sequencer.h" /* free seq clipboard */
+#include "SEQ_clipboard.h" /* free seq clipboard */
 
 #include "IMB_thumbs.h"
 
diff --git a/source/blender/windowmanager/intern/wm_jobs.c b/source/blender/windowmanager/intern/wm_jobs.c
index 2e794940f26..cf45d380c48 100644
--- a/source/blender/windowmanager/intern/wm_jobs.c
+++ b/source/blender/windowmanager/intern/wm_jobs.c
@@ -36,7 +36,7 @@
 #include "BKE_context.h"
 #include "BKE_global.h"
 
-#include "SEQ_sequencer.h"
+#include "SEQ_prefetch.h"
 
 #include "WM_api.h"
 #include "WM_types.h"