[FFmpeg-devel] Channel layouts for aac encoding/decoding and vorbis decoding

Jason Tackaberry tack
Mon Aug 10 20:45:28 CEST 2009

On Mon, 2009-08-10 at 11:32 -0700, Frank Barchard wrote:
> The actual layout we settle on is not that important - its just important
> that we pick one.
> It could also be different per platform, if really necessary, so long as
> there are macros to specify the channel order.
> By far the emphasis is 5.1, but if we could make all the other layouts
> consistent and easy, that would be nice.

I'm under the impression a good deal of work had already gone into this
task last year (the "Channel layouts" thread started August 2008, which
I mentioned in my initial email).

The channel order is at least clearly defined by the CH_* values in
avcodec.h (whose bits from LSB to MSB specify the order, which
corresponds to the Wave order).  So at this point it's a matter of
gradually migrating the remaining codecs to the new standard channel

Hopefully at least the AAC and Vorbis decoder maintainers can give me
some idea of how likely the current order is to change over the medium
term.  (I've already heard from Alex on the AAC encoder and adapting the
channel layout is not on his radar.)


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