[FFmpeg-devel] [PATCH] lavf/concatdec: fix timestamp conversion

Nicolas George george at nsup.org
Sun Nov 23 20:14:37 CET 2014

Le nonidi 29 brumaire, an CCXXIII, Stefano Sabatini a écrit :
> I agree. At the moment nor the code nor the documentation mentions
> this. Ideally the library should complain in case different settings
> are detected.

The documentation says: "All files must have the same streams (same codecs,
same time base etc.)."

I do not think the library must enforce it, because it is always possible to
have cases where it will work, if just per happenstance.

> As for the timebase issue, probably a workaround can be found using a
> settb filter.

It can not work, filters happen after demuxers. If your first segment has
25 FPS, the demuxer will select that as a time base, then if the second one
has 30, then one frame out of six will have timestamps rounded with a
collision, there is no way around it with the current working.

The obvious solution would be to probe all segments at startup, but I do not
want that, at least by default, because it would be too slow and clumsy.

Another obvious solution is to have the user specify the time base in the
concat script.

Anyway, as I said, I do not oppose the patch, it probably gets working a few
cases that did not work before, and that is in itself a good thing. I just
want you to be aware of how limited it is.


  Nicolas George
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