[Ffmpeg-devel] channel ordering and downmixing

[Michael Niedermayer]

Hi

On Mon, Apr 09, 2007 at 05:58:45PM -0400, Justin Ruggles wrote:
> Andreas ?man wrote:
> > Hi,
> > 
> > Justin Ruggles wrote:
> > 
> > 
> >>Decoding:
> >>If required, the decoder sets AVCodecContext->channel_layout to the
> >>channel layout of the input audio stream.  If downmixing is done in the
> >>decoder (current situation), the final downmixed channel layout is
> >>considered the input layout.
> > 
> > 
> > It would be nice, at least for interactive applications, to be able
> > to retrieve the original channel layout, for presentation purposes.
> > But perhaps the long term idea is that no codec should perform its own
> > downmixing? Either way, I suggest that we add an additional pointer
> > AVCodecContext->original_channel_layout (or something) that is never
> > messed with by any (codec internal) downmixers at all.
> 
> The downmixing will indeed be moved out of the decoders.  I was just
> pointing out how the new channel layout scheme would fit into the
> existing downmixing scheme.  Downmixing outside of the decoders is the
> next step once channel layout/reordering is complete.

downmixing outside the decoders is needed yes, but downmixing support
inside the decoders cannot be removed as it often is faster to downmix
inside the decoder ...

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

The educated differ from the uneducated as much as the living from the
dead. -- Aristotle 
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