[FFmpeg-devel] [RFC] Channel layouts

[Dominik 'Rathann' Mierzejewski]

On Friday, 29 August 2008 at 16:35, Andreas ?man wrote:
> Dominik 'Rathann' Mierzejewski wrote:
> > What if you have 4 speakers but in a different layout than the
> > encoded one? With the two layouts above (C+L+R+S encoded and L+R+SL+SR
> > speakers) I'd expect the sound to come out of the front speakers only,
> > with C+S channels mixed equally with L and R. This could be done by the
> > codec or an audio filter if the codec isn't capable.
> 
> This belongs to the audio layer of a mediaplayer IMHO.
> Most AV Amplifiers support stuff like:
> 
> * Phantom Center         (Mix C to L+R)
> * Phantom LFE            (Mix LFE to L+R)
> * Small Front speakers   (in 2ch mode, mix L+R to LFE)
> etc...
> 
> certainly it should stay out of the codecs.

But it might be faster to downmix upon decoding. I'm told there
are asm optimizations to be easily made in common cases.

Regards,
R.

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