[FFmpeg-devel] lavfi: expected behavior for multiple filter?definitions

Stefano Sabatini stefano.sabatini-lala at poste.it
Thu Mar 31 17:04:05 CEST 2011

On date Thursday 2011-03-31 15:21:19 +0200, Mina Nagy Zaki encoded:
> On Wednesday 30 March 2011 13:09:24 Michael Niedermayer wrote:
> > On Wed, Mar 30, 2011 at 07:30:32AM +0200, Mina Nagy Zaki wrote:
> > > What is the expected behavior of:
> > > ffmpeg -i in.mp3 -af aresample=8000 out1.mp3 -af earwax out2.mp3
> > 
> > it should behave the same as with video filters.
> > 
> > [...]
> They are both equally broken (IMHO) in that only the last -vf/-af is ever 
> evaluated and the rest are discarded.

Can you verify with the latest git (and corresponding audio branch),
this should be already fixed.

For example this works here:
ffmpeg -i slow.flv -vf scale=200:-1 slow1.mov -vf scale=300:-1 slow2.mov

> Actually each -af could simply add on to 
> the filter graph definition, inserting new links/filters, and then when an output 
> file is specified a new aout/vout is created and linked to the last available 
> open output. This way multiple output files can be inserted easily at different 
> parts of the graph, or even multiple independent chains (and hence independent 
> outputs) can all be connected to a single src.

This is actually the last design we'll implement, but one step at a
time, since this will possibly require a major revamp of the ffmpeg.c
FFmpeg = Frightening Fascinating Mastodontic Philosophical Ecumenical Gadget

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