[FFmpeg-devel] Evolution of lavfi's design and API

Nicolas George george at nsup.org
Sun Sep 4 23:16:57 EEST 2016

Le nonidi 19 fructidor, an CCXXIV, Paul B Mahol a écrit :
> And what would that cleaner implementation do?

There is a rather simple implementation of format change in lavfi: have on
each input a boolean flag "can_deal_with_format_change". If a frame with a
different format arrives on a filter that does not have the flag, just
insert the scale/aresample filter on the link to force the format to be the

It is not entirely optimal, but it is quite simple and does the work.

And it could probably be implemented independently of my changes. But I do
not want to spend time on it before finishing this, or it will never end.

(Actually, I think we had something like that for buffersrc but it
disappeared at some time. avconv also has some very strange code to handle
format changes.)

> At current rate your lavfi changes will never get in, which sucks.

Which is why I would like to be authorized to ignore this kind of hiccups.
Format change does not currently work, this particular case used to work
only by chance. Can I break it and repair it later?


  Nicolas George
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