[flac-dev] Flac multi channel

[Olivier Tristan]

This could make sense indeed.
I suppose this is not a libFlac feature and that I should end up using
libogg and or adding myself basic ogg support
in order to support that ?

Thanks !

2017-01-28 7:37 GMT+01:00 Brian Willoughby <brianw at audiobanshee.com>:

> Don't overlook the FLAC in Ogg container solution. That's established as a
> standard for some time now, as far as I know, and would probably be better
> than a new, proprietary multi mono bundle. I haven't used it myself, but
> people have been talking about it for a while, and I believe that some
> "FLAC" users are actually working with FLAC in Ogg container files.
>
> Brian Willoughby
>
>
> On Jan 27, 2017, at 12:55 AM, Olivier Tristan <o.tristan at uvi.net> wrote:
> > 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
www.uvi.net
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