flac dev - Jul 2015 - WAVEFORMATEXTENSIBLE_CHANNEL_MASK is not described

An issue was raised at
<http://forum.doom9.org/showthread.php?p=1728923#post1728923> -
FLAC uses WAVEFORMATEXTENSIBLE_CHANNEL_MASK tag to describe non-standard layout,
but it isn't mentioned anywhere in FLAC format.

Channel assignment is described at
<https://xiph.org/flac/format.html#frame_header>:
"Where defined, the channel order follows SMPTE/ITU-R
recommendations."

The undefined value (0000?) is not mentioned. And no mentions that FLAC can
store channel assignment in WAVEFORMATEXTENSIBLE_CHANNEL_MASK tag, and how and
when to use it.

Maybe I don't understand you correctly, but 0000 is mono, not undefined. It
says: 0000-0111 : (number of independent channels)-1

I agree that the use of WAVEFORMATEXTENSIBLE_CHANNEL_MASK should be
documented. I can probably take a look at it this week or so, if no one
hasn't already?

2015-07-05 13:54 GMT+02:00 lvqcl <lvqcl.mail at gmail.com>:
> An issue was raised at <
> http://forum.doom9.org/showthread.php?p=1728923#post1728923> -
> FLAC uses WAVEFORMATEXTENSIBLE_CHANNEL_MASK tag to describe non-standard
> layout,
> but it isn't mentioned anywhere in FLAC format.
>
> Channel assignment is described at <
> https://xiph.org/flac/format.html#frame_header>:
> "Where defined, the channel order follows SMPTE/ITU-R
recommendations."
>
> The undefined value (0000?) is not mentioned. And no mentions that FLAC can
> store channel assignment in WAVEFORMATEXTENSIBLE_CHANNEL_MASK tag, and how
> and
> when to use it.
> _______________________________________________
> flac-dev mailing list
> flac-dev at xiph.org
> http://lists.xiph.org/mailman/listinfo/flac-dev
>
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Martijn van Beurden wrote:
> Maybe I don't understand you correctly, but 0000 is mono, not
undefined. It
> says: 0000-0111 : (number of independent channels)-1
You're right of course.

 From FLAC 1.2.1 documentation:

0000-0111 : (number of independent channels)-1. Where defined, the channel order
follows SMPTE/ITU-R recommendations. The assignments are as follows:
1 channel: mono
2 channels: left, right
3 channels: left, right, center
4 channels: left, right, back left, back right
5 channels: left, right, center, back/surround left, back/surround right
6 channels: left, right, center, LFE, back/surround left, back/surround right
7 channels: not defined
8 channels: not defined

It was more obvious that "where defined" means 1-6 channels, and 7 and
8-channel
files have undefined channel assignment. Now all possible numbers of channels
have
defined channel map, so the text should be (IMHO):

0000-0111 : (number of independent channels)-1. The channel order follows
SMPTE/ITU-R recommendations. The assignments are as follows:
...
...