[Libav-user] Update filter settings at runtime

[Andrey Utkin]

I'd also appreciate qualified answer to this question.
If there will not be found any smart ability to do so, you can go with
just recreating the whole filtergraph when settings change. I. e. you
flush remaining frames from filtering mechanism, free AVFilterGraph,
and create a new one for usage. But if used filters' output is
dependent on previous frames, this is not acceptable solution.