[FFmpeg-user] Question about concat protocol

Nicolas George nicolas.george at normalesup.org
Mon Oct 29 20:27:57 CET 2012


L'octidi 8 brumaire, an CCXXI, Jan Ehrhardt a écrit :
> Couldn't this be fixed within FFMpeg by adding an extra variable to be
> used by the complex filter? Something like MINSTARTPTS which is the
> minimum of the STARTPTS's of all streams or FIRSTPTS = the PTS of the
> first frame in the file, whatever type it is.

Anything is possible, provided someone implements it. Currently, the
STARTPTS variable that is available in the setpts filter comes from the
stream itself: it is the PTS of the first filtered frame, the filter has no
way of knowing anything else.

One possible solution would be to inject information about the file using
the new metadata API. That requires some work on various parts of the code,
including the expression evaluation engine, but that would be doable.

Another possible solution, more ad-hoc, would be to have the concat filter
(optionally) do the initial timestamps adjustment.

But note that it can not solve the problem of streams overlapping from one
segment to the other, as is the case here. They require a different handling
altogether.

Regards,

-- 
  Nicolas George
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