[flac-dev] Define 6.1 and 7.1 channel mappings

[rsdio at sounds.wa.com]

On Jan 1, 2013, at 13:02, Ralph Giles wrote:
> On 12-10-12 4:47 AM, Erik de Castro Lopo wrote:
>> I've read through this thread and it didn't really come to any
>> conclusion. Can we try again and make a decision this time?
>
> Anyone else have thoughts on this? I'd like to get this added  
> before the
> 1.3.x release. Especially helpful would be research into what current
> tools actually do.

There doesn't seem to be a single standard for this. Where some seem  
to prefer L R C LFE Ls Rs Rls Rrs, I've seen many professional  
standards that put C/LFE last, as in L R Ls Rs (Rls Rrs) C LFE.  
Someone mentioned SMPTE/ITU-R recommendations, but didn't know what  
they were. I think that an important starting point would be to make  
a detailed examination of existing standards before jumping to add  
something to FLAC without thorough research.

Adding to the complications, the user may have wired their system  
differently (i.e. between their audio interface and their amplifier  
channels and/or powered speakers). Seems the only sensible choice is  
meta data in the FLAC that reflects the channel order in a way that a  
playback application can re-patch channel order if necessary. I  
believe that CAF has meta data for this, or at least CoreAudio does.  
That way, channel order can vary, but will be marked correctly in a  
consistent way that can be deciphered by playback software.

Brian Willoughby
Sound Consulting