[FFmpeg-trac] #7476(undetermined:new): Invalid pts and duration generated for mp4 when converting from webm

FFmpeg trac at avcodec.org
Mon Oct 8 12:07:26 EEST 2018


#7476: Invalid pts and duration generated for mp4 when converting from webm
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             Reporter:  jyavenard    |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  normal       |                Component:
              Version:  unspecified  |  undetermined
             Keywords:               |               Resolution:
             Blocking:               |               Blocked By:
Analyzed by developer:  0            |  Reproduced by developer:  0
-------------------------------------+-------------------------------------

Comment (by Gyan):

 WebM files, especially when geenerated via WebRTC, often show the
 reciprocal of the timebase as their framerate. The timebase for
 Matroska/WebM files is 1/1000.

 The MP4 muxer defaults to constant frame rate, so with your first command,
 ffmpeg will duplicate frames to achieve a 1000 fps output. In this output,
 each frame will obviously have duration 1/1000 s.

 Use

     `ffmpeg -i MozilleTest -vsync 0 -c:v libx264 test.mp4`

 to preserve original timestamps with no frame duplication. The resulting
 file will have an avg rate of 30.04.

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Ticket URL: <https://trac.ffmpeg.org/ticket/7476#comment:2>
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