[FFmpeg-trac] #2446(FFplay:new): ffplay frame drop playback broken (regression)

[FFmpeg]

#2446: ffplay frame drop playback broken (regression)
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             Reporter:  ubitux       |                    Owner:
                 Type:  defect       |                   Status:  new
             Priority:  important    |                Component:  FFplay
              Version:  git-master   |               Resolution:
             Keywords:  framedrop    |               Blocked By:
  regression                         |  Reproduced by developer:  0
             Blocking:               |
Analyzed by developer:  0            |
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Changes (by cus):

 * cc: cus@… (added)


Comment:

 This seems like a bug and a regression, but it's not necessarily one.

 By default, if ffplay is playing video without audio, it uses as external
 clock as a sync source. This basically means that video playback is synced
 to your PC clock and this ensures that video is played in realtime and
 with frame drops if displaying a frame or filtering a frame would take too
 much time.

 In this case reading from the source is what's cannot be done in real
 time. FFplay early framedrop code drops the frames before passing them to
 the filter chain if the read frame's timestamp is late at the time of
 reading it, and that is always the case if the your source cannot be read
 in realtime.

 Actually in this case there would be no point in dropping any of the
 frames, because by the time you get the next frame you will be more late
 than the last time. Syncing to external clock simply cannot be done.

 A workaround for this is to use the -sync video paramter when playing the
 file.

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Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2446#comment:3>
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