[FFmpeg-trac] #2446(FFplay:new): ffplay frame drop playback broken (regression)
FFmpeg
trac at avcodec.org
Thu Apr 11 23:41:13 CEST 2013
#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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