[FFmpeg-user] Reducing seek time when start time offset (-ss) is large

Nicolas George nicolas.george at normalesup.org
Mon Aug 13 12:06:09 CEST 2012

Le sextidi 26 thermidor, an CCXX, Robert Krüger a écrit :
> in my case the requirement was frame-accurate seeking and I am still
> getting different (less reliable) results with -ss as an input option
> depending on container format and probably other specifics of the
> video stream.

You are right, -ss as input option is less accurate, as it is, apart from
bugs and misfeatures, limited to keyframes.

But your wording makes me wonder if you did not miss part of my message: I
did not suggest to use -ss as input option but to use it BOTH as input and
output option: the input option causes ffmpeg to seek to the keyframe
immediately before the target time and the output option causes it to skip
the frame to the exact target time.

With formats that have valid timestamps at seek points, it should be
frame-accurate, although it seems to be only frame-accurate±1, and I need to
find time to examine why.

Note that MPEG-PS is rather a crappy format, especially for seeking, which
explains Michael Bradshaw's problems.


  Nicolas George
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