[FFmpeg-devel] FOMS 2009 FFmpeg outbrief

Reimar Döffinger Reimar.Doeffinger
Tue Jan 27 10:31:24 CET 2009

On Tue, Jan 27, 2009 at 09:45:25AM +0100, Jean-Baptiste Kempf wrote:
> On Mon, Jan 26, 2009 at 11:10:12PM +0100, Reimar D?ffinger wrote :
> > There are only two dependencies I know of: AVParser (which I think is
> > unavoidable) and that extradata formats may be incompatible (theora, and
> > IMHO it is justified to blame that on Ogg-braindeadness).
> We never said that this would be easy, we just said that this would be
> cool.

I think you misunderstood my point: there are different kind of dependencies:
1) libavformat must be linked against libavcodec - this does not really
seem worth the effort of avoiding it to me, and some things like codec
ids simply _must_ be shared between them so either you have to
duplicate code or you need at least the headers for both.
2) Some output of libavformat can only be processed by libavcodec, but
not e.g. the binary codecs.

These are completely different things and it was/is unclear to me which
you meant - which is why I want specific examples so much.

> > > - feature probing API (to find out supported formats/other
> > > functionality from the libraries rather than guessing from version
> > > number and
> > >   other information)
> > >   e.g. get_fourcc() would simplify this:
> > > http://git.videolan.org/?p=vlc.git;a=blob;f=modules/codec/avcodec/fourcc.c;
> > You are aware of avcodec_find_decoder and av_codec_next ?
> > Of course that will not solve the issue of the codec ids not being
> > defined, but that seems unavoidable...
> > About probing other functionality: more specific examples would be good.
> Well, this is more about the issue of some distributions removing
> decoders/encoders or adding some and this is quite difficult to manage.
> A way of detecting that would be nice.

Again: aren't avcodec_find_decoder and/or av_codec_next enough?
If no, why not?
If yes, what can we do to help developers become aware of them?

Reimar D?ffinger

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