The stream header only has 3 bits for the channel count, so it's not possible 
to support more than 8 channels without breaking compatibility with all 
embedded products that support FLAC, not to mention old and existing software. 
Part of the benefit of FLAC is that it enjoys such wide support across computer 
operating systems and embedded devices like audio players and digital recorders 
- I'd strongly recommend against changing something this low-level just for a 
little convenience for rare channel counts.

It might be worth losing compatibility with the existing installed base if 
there were any real advantage to higher channel counts, but there really isn't. 
FLAC can do extra compression on stereo files, such that one 2-channel FLAC can 
take less space than two 1-channel FLAC files. However, the compression 
advantages stop at 2 channels. There is no cross-compression with channels 
beyond 2. You might as well store separate FLAC files and group them in a 
directory.

Note that software like ProTools stores each channel in its own file. So, at 
least the original FLAC format supports more than that. I do often take 
advantage of the additional compression by converting audio recordings from 
dual mono files into a single stereo file before compression.

There might still be a solution for you, though. Ogg and other formats can 
embed FLAC data inside another container, so it might be possible to create a 
16-channel "FLAC" in an Ogg container as two 8-channel FLAC files or even as 
eight stereo FLAC files for maximum compression. I don't know whether Ogg is 
optimized for streaming such that it could interleave multiple FLAC files this 
way, but it's worth investigating.

Brian Willoughby
Sound Consulting


On Oct 28, 2016, at 6:24 PM, J.B. Nicholson <j...@forestfield.org> wrote:
> Per https://xiph.org/flac/faq.html#general__channels currently FLAC supports 
> 1 through 8 channels. This is fine for 5.1 surround sound (6 channels). But 
> some of the newer surround sound systems can handle many more channels. Is it 
> still convenient to have all of the audio channels in one file for, say, a 16 
> channel audio track?
> 
> I don't know much about the history of FLAC. How did this many channels come 
> to be the number supported? Is there any interest in increasing the number of 
> channels?
> 
> Thanks for all the hard work on FLAC, I continue to get a lot of use out of 
> FLAC.
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