[FFmpeg-trac] #1866(undetermined:new): Half speed video output ts -> flv transcode

FFmpeg trac at avcodec.org
Mon Oct 29 18:29:54 CET 2012

#1866: Half speed video output ts -> flv transcode
             Reporter:  larvalho  |                    Owner:
                 Type:  defect    |                   Status:  new
             Priority:  normal    |                Component:  undetermined
              Version:  1.0       |               Resolution:
             Keywords:            |               Blocked By:
             Blocking:            |  Reproduced by developer:  0
Analyzed by developer:  0         |
Changes (by cehoyos):

 * component:  FFmpeg => undetermined


 Replying to [ticket:1866 larvalho]:
 > Summary of the bug:
 > Some mpeg 2 ts files (h264 + aac, generated by Crestron Lecture
 Capture), when transcoded using ffmpeg to flv, produce video that plays
 back at half the speed (frame rate is retained but number of frames is
 doubled), while the audio is rendered correctly.  There is a 10 minute
 delay to the video, but this is in the original file, and eliminated with
 a '-vf setpts=PTS-STARTPTS'.

 I am not sure I understand:
 Is the original file supposed to play (ie with video and audio)?
 Or is the 10 minute delay intentional?
 In the first case, I would suspect this is a duplicate of ticket #424, in
 the second case, I wonder how ffmpeg is supposed to transcode the stream?
 Shouldn't it try hard to eliminate the A/V desync (leading to slow or fast

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/1866#comment:1>
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