[FFmpeg-devel] [RFC] Channel layouts

Dominik 'Rathann' Mierzejewski dominik
Fri Aug 29 16:29:44 CEST 2008

On Friday, 29 August 2008 at 16:23, madshi wrote:
> Benjamin Larsson schrieb:
> > We also need to add a parameter to request the decoded channelmask. For 
> > example dca have 2 4 channel layouts. Without a requested channelmask it 
> > would only be possible to get 1 layout.
> >   
> The DTS header specifies which layout the DTS was encoded with.
> See bitstream field "Audio Channel Arrangement". E.g. value 7
> means "C + L + R+ S" while value 8 means "L + R+ SL+SR".
> What sense does it make to request a different decoded channel
> mask then is stored in the DTS track?

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.


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