[FFmpeg-trac] #933(undetermined:new): A/V desynch when transcoding A/V files with timestamps non starting from 0 with -copyts
FFmpeg
trac at avcodec.org
Mon Jan 23 20:11:09 CET 2012
#933: A/V desynch when transcoding A/V files with timestamps non starting from 0
with -copyts
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Reporter: saste | Owner:
Type: defect | Status: new
Priority: normal | Component:
Version: git-master | undetermined
Keywords: timestamp | Resolution:
desynch mpegts | Blocked By:
Blocking: | Reproduced by developer: 1
Analyzed by developer: 0 |
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Comment (by mjs973):
From what I can see in the code, -copyts does the right thing only when
you also use '-acodec copy'. This command line works for me:
./ffmpeg -vsync 0 -copyts -i columbia-intro.ts -vcodec mpeg2video -b:v
3000000 -acodec copy out.ts
...and the proper time offset between the first audio and video packets is
maintained.
So, the short answer is that ffmpeg (the app) doesn't yet support what you
want to do.
The more detailed answer is that, if you try to actually encode the audio
stream, ffmpeg.c looks like it always calls avcodec_encode_audio*() with
the avpkt.pts timestamp set to AV_NOPTS_VALUE. Later on, this will cause
av_interleaved_write_frame() to make up timestamps, starting at 0.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/933#comment:5>
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