VSE: Fix audaspace not reading ffmpeg files with start offset correctly

The duration and start time for audio strips were not correctly read in
audaspace.

Some video files have a "lead in" section of audio that plays before the
video starts playing back. Before this patch, we would play this lead in
audio at the same time as the video started and thus the audio would not
be in sync anymore.

Now the lead in audio is cut off and the duration should be correctly
calculated with this in mind.

If the audio starts after the video, the audio strip is shifted to
account for this, but it will also lead to cut off audio which might not
be wanted. However we don't have a simple way to solve this at this
point.

Differential Revision: http://developer.blender.org/D11917

2 files changed, 14 insertions, 7 deletions

diff --git a/source/blender/blenkernel/BKE_sound.h b/source/blender/blenkernel/BKE_sound.h
index 57ce33a239f..4b257b3b8ab 100644
--- a/source/blender/blenkernel/BKE_sound.h
+++ b/source/blender/blenkernel/BKE_sound.h
@@ -97,6 +97,7 @@ typedef struct SoundInfo {
     eSoundChannels channels;
   } specs;
   float length;
+  double start_offset;
 } SoundInfo;
 
 /* Get information about given sound. Returns truth on success., false if sound can not be loaded
@@ -139,8 +140,12 @@ void BKE_sound_remove_scene_sound(struct Scene *scene, void *handle);
 
 void BKE_sound_mute_scene_sound(void *handle, char mute);
 
-void BKE_sound_move_scene_sound(
-    struct Scene *scene, void *handle, int startframe, int endframe, int frameskip);
+void BKE_sound_move_scene_sound(struct Scene *scene,
+                                void *handle,
+                                int startframe,
+                                int endframe,
+                                int frameskip,
+                                double audio_offset);
 void BKE_sound_move_scene_sound_defaults(struct Scene *scene, struct Sequence *sequence);
 
 void BKE_sound_update_scene_sound(void *handle, struct bSound *sound);
diff --git a/source/blender/blenkernel/intern/sound.c b/source/blender/blenkernel/intern/sound.c
index 6dd1f66f6b5..284c5db10b3 100644
--- a/source/blender/blenkernel/intern/sound.c
+++ b/source/blender/blenkernel/intern/sound.c
@@ -709,7 +709,7 @@ void *BKE_sound_scene_add_scene_sound(
                             sequence->scene->sound_scene,
                             startframe / fps,
                             endframe / fps,
-                            frameskip / fps);
+                            frameskip / fps + sequence->sound->offset_time);
   }
   return NULL;
 }
@@ -737,7 +737,7 @@ void *BKE_sound_add_scene_sound(
                                   sequence->sound->playback_handle,
                                   startframe / fps,
                                   endframe / fps,
-                                  frameskip / fps);
+                                  frameskip / fps + sequence->sound->offset_time);
   AUD_SequenceEntry_setMuted(handle, (sequence->flag & SEQ_MUTE) != 0);
   AUD_SequenceEntry_setAnimationData(handle, AUD_AP_VOLUME, CFRA, &sequence->volume, 0);
   AUD_SequenceEntry_setAnimationData(handle, AUD_AP_PITCH, CFRA, &sequence->pitch, 0);
@@ -765,11 +765,11 @@ void BKE_sound_mute_scene_sound(void *handle, char mute)
 }
 
 void BKE_sound_move_scene_sound(
-    Scene *scene, void *handle, int startframe, int endframe, int frameskip)
+    Scene *scene, void *handle, int startframe, int endframe, int frameskip, double audio_offset)
 {
   sound_verify_evaluated_id(&scene->id);
   const double fps = FPS;
-  AUD_SequenceEntry_move(handle, startframe / fps, endframe / fps, frameskip / fps);
+  AUD_SequenceEntry_move(handle, startframe / fps, endframe / fps, frameskip / fps + audio_offset);
 }
 
 void BKE_sound_move_scene_sound_defaults(Scene *scene, Sequence *sequence)
@@ -780,7 +780,8 @@ void BKE_sound_move_scene_sound_defaults(Scene *scene, Sequence *sequence)
                                sequence->scene_sound,
                                sequence->startdisp,
                                sequence->enddisp,
-                               sequence->startofs + sequence->anim_startofs);
+                               sequence->startofs + sequence->anim_startofs,
+                               sequence->sound->offset_time);
   }
 }
 
@@ -1213,6 +1214,7 @@ static bool sound_info_from_playback_handle(void *playback_handle, SoundInfo *so
   AUD_SoundInfo info = AUD_getInfo(playback_handle);
   sound_info->specs.channels = (eSoundChannels)info.specs.channels;
   sound_info->length = info.length;
+  sound_info->start_offset = info.start_offset;
   return true;
 }