[Bf-blender-cvs] [88604b79b7d] master: FFmpeg: Improve scrubbing performance

[Richard Antalik]

Commit: 88604b79b7d15f8aa86fbd2d23d58541aa927313
Author: Richard Antalik
Date:   Tue Mar 2 12:13:21 2021 +0100
Branches: master
https://developer.blender.org/rB88604b79b7d15f8aa86fbd2d23d58541aa927313

FFmpeg: Improve scrubbing performance

Applying negative offset to seek position before scanning doesnn't have
any effect. This change results in 1.5x faster seeking (random frame,
average value) in sample file with 30 frame GOP length.

If I am not mistaken, B frames can have pts that can be less than
pts of I frame that must be decoded. Even in this case though, B frame
packet will be stored after that I frame.

In addition, preseek value is de facto hardcoded so seeking would fail
if it could. This can be hard to spot though.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D10529

===================================================================

M	source/blender/imbuf/intern/anim_movie.c

===================================================================

diff --git a/source/blender/imbuf/intern/anim_movie.c b/source/blender/imbuf/intern/anim_movie.c
index 28bf26aa343..d36c7bbe486 100644
--- a/source/blender/imbuf/intern/anim_movie.c
+++ b/source/blender/imbuf/intern/anim_movie.c
@@ -1149,7 +1149,7 @@ static ImBuf *ffmpeg_fetchibuf(struct anim *anim, int position, IMB_Timecode_Typ
       }
     }
     else {
-      pos = (int64_t)(position - anim->preseek) * AV_TIME_BASE / frame_rate;
+      pos = (int64_t)position * AV_TIME_BASE / frame_rate;
 
       av_log(anim->pFormatCtx,
              AV_LOG_DEBUG,