[FFmpeg-trac] #933(FFmpeg:new): A/V desynch when transcoding A/V files with timestamps non starting from 0 with -copyts
FFmpeg
trac at avcodec.org
Fri Jan 20 18:24:43 CET 2012
#933: A/V desynch when transcoding A/V files with timestamps non starting from 0
with -copyts
-------------------------------------+-------------------------------------
Reporter: saste | Owner:
Type: defect | Status: new
Priority: normal | Component: FFmpeg
Version: git- | Keywords: timestamp
master | desynch mpegts
Blocked By: | Blocking:
Reproduced by developer: 1 | Analyzed by developer: 0
-------------------------------------+-------------------------------------
Using the command:
{{{
ffmpeg -vsync 0 -copyts -i columbia-intro.ts -acodec libfaac -y columbia-
intro.out.ts
}}}
(same without -vsync) the A/V streams in the output file result desynched,
and will result in the video being unplayable. This seems due to the first
audio packet timestamp information not being correctly propagated to the
encoder (and to the muxer), and being set to 0, so that ffmpeg will fill
the first part of the file with audio packets, and the probe will fail
since ffmpeg can't detect video frames in the probed initial part of the
file.
Same result in case I use the -copyts with no -vsync. If the output file
only contains video (e.g. if the -an switch is used) the output file seems
to be correctly generated (playable and with correct timestamp
information).
I'm attaching a sample file and log obtained by adding debugging print in
ffmpeg.c.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/933>
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