[FFmpeg-devel] Mutlichannel API for aac.c

Michael Niedermayer michaelni
Sun Nov 9 22:59:30 CET 2008

On Sun, Nov 09, 2008 at 09:56:10PM +0100, Andreas ?man wrote:
> Michael Niedermayer wrote:
> > On Sun, Nov 02, 2008 at 10:25:36PM +0100, Andreas ?man wrote:
> >> Hi,
> >>
> >> aac1.patch is basically some refactoring.
> > 
> > iam mildly against this, at least without renaming the involved functions
> > to repesent the new merged behavior and fully documenting it but with these
> > its likely no longer a win in terms of amount of code.
> > 
> > 
> >> aac2.patch does the stuff but depends on mpeg4audio.patch.
> > 
> > iam against this patch, not only does it replace apparently
> > unrelated code by a more complex and more messy implementation, it also
> > does not seem to implement channel layouts correctly. Rather it just hardcodes
> > them for defaults while ignoring non defaults.
> Well, the default set is pretty hardcoded, I can't say I follow you
> there. Perhaps you are referring to the fact that the channel output
> order would be same even if we change the CH_ -defines in avcodec.h ?

> Also, the non-defaults are just a set of stereo, mono and LFE-channels.
> I have not found any info in the specs how to map these to speaker
> positions.
> Of course, one could assume that for a equal setup as in a default
> setting, the speaker mappings would be the same.
> I'll see if I can come up with something.

the way i understand the code, they are at least split in front/side/back
and together with stereo/mono this really should be enough for channel


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

it is not once nor twice but times without number that the same ideas make
their appearance in the world. -- Aristotle
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