[FFmpeg-user] 'key' frame only decoding

Nicolas George george at nsup.org
Mon Jun 1 17:23:35 EEST 2020

rohit khali (12020-06-01):
> As part of initial checks, I came across below command, which seems to be
> working however was wondering why '-vsync 0' parameter is needed.

The output format you are using does not support timestamps, and
therefore must be used with constant frame rate, but keyframes are not
guaranteed to be constant frame rate. Therefore, ffmpeg will duplicate
frame as needed to meet the constant frame rate, by default the same as
the input.

-vsync 0 disables that: it tells ffmpeg to not bother about timestamps.


  Nicolas George
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