[flac-dev] Flac multi channel

Olivier Tristan o.tristan at uvi.net
Fri Jan 27 08:55:31 UTC 2017

Thanks everybody for their answer.

This is quite unfortunate for me, but hey, that's life.

I will probably end up doing some multi mono bundle similar to what 
Protools did back in the days with its .L .R files


Le 26/01/2017 à 18:58, Martin Leese a écrit :
> Federico Miyara wrote:
> ...
>> The file format allows some unused fields for future use, such as the
>> padding block. It could include a flag to indicate a change in the
>> format adding one more streaminfo byte which would allow up to 256
>> channels (actually, 256 + 8), or it could trigger a new byte when 11111111.
>> There is also an invalid block identifier (127) which could be used with
>> the same purpose.
> The problem isn't *just* the 3-bit field used for
> the number of channels.  As Brian Willoughby
> explained:
> ...
>>> As you cram more channels into a block, you get fewer samples per block for
>>> each individual channel. There simply isn't any advantage to having lots of
>>> channels in a single stream.
>>> I believe that Ogg allows you to create a file that interleaves multiple
>>> FLAC files.
> Perhaps comparing FLAC with the Ogg
> container and Vorbis codec will aid
> understanding.
> With Ogg, different streams can be either
> chained (sequential) or grouped
> (parallel/interleaved).  Typically, metadata
> streams would be chained (so they appear
> before any audio data) and audio streams
> would be grouped.
> Within a single FLAC stream the audio is
> split into blocks which are grouped.  But within
> each block the eight channels are chained.
> This makes sense with a maximum of only
> eight channels.  Within a Vorbis stream the
> audio is split into frames which are grouped.
> Because a Vorbis stream can contain up to
> 256 channels, within each frame the channels
> are also grouped.
> So the maximum of eight channels is really
> embedded into the FLAC standard.  To change
> this would require a whole new standard (or
> the use of multiple grouped FLAC streams in
> an Ogg container).
> Regards,
> Martin

Olivier Tristan
Research & Development

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