[FFmpeg-devel] [RFC] Channel layouts

Dominik 'Rathann' Mierzejewski dominik
Fri Aug 29 16:41:34 CEST 2008

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.


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