[Ffmpeg-devel] channel ordering and downmixing

[Justin Ruggles]

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.

-Justin