Multi channel flac file problem [#13879]

[jwhitworth]

MMW5 has fixed most of the issues I reported with MMW4 with respect to reporting the proper number of channels in a flac file.

However there is still a problem with 4.1 channel flac files. There are reported as 5.0

5.1, 5.0 and 4.0 flac files all display the proper number of channels.

[MiPi]

Problem is, that MM parses and stores only number of channels, not presence of LFE.
Added as http://www.ventismedia.com/mantis/view.php?id=13879

[jwhitworth]

Ok. MMW5 manages to get 5.1 right. Looks like the issue will be addressed.

I did find an additional example of a 3 channel audio file being identified as 2.1. That file was originally 5.0 with blank surround channels which I then exported only the real three channels using Audacity and the original surround channels are still listed --> Channels : 3: FL FR FC BL BR. Correct on number of channels but still lists BL BR. I need to bring that up with the Audacity people.

[MiPi]

I don't understand, where are the channel positions listed? MM5 cannot list channel positions (and that is why it cannot differentiate between 2.1 and 3.0).

[jwhitworth]

Sorry for the confusion.

The channel positions are listed somewhere in the flac file header?

As stated in the http://www.ventismedia.com/mantis/view.php?id=13879 MMW5 will have to parse the info and determine the correct channel configuration.

I just found it weird that MMW currently decides a 3 channel flac file is 2.1 as opposed to a 3.0. Must be making some assumptions.

There will be some isssues with nomenclature that MMW5 will have to "learn". I have seen files with the surround channels being refered to as both
SL SR and/or BL BR. Not really an issue with 4 and 5 channel audio since they can be interpreted as interchangeable but with 7 channels it would be important.

Not sure where the info comes from to begin with. The various programs that convert SACD, DVD-Audio and Blu-ray audio may decide what is what. Not sure. I have yet to find a program that can actually edit the channel descriptors.

I could see where it would be possible for MMW to provide the little graphical description of the channel configuration as seen on the back cover of various media.

[MiPi]

Looked at it a little bit and It seems, FLAC has defined only these channel assignments in standard:
1 channel: mono
2 channels: left, right
3 channels: left, right, center
4 channels: front left, front right, back left, back right
5 channels: front left, front right, front center, back/surround left, back/surround right
6 channels: front left, front right, front center, LFE, back/surround left, back/surround right
7 channels: front left, front right, front center, LFE, back center, side left, side right
8 channels: front left, front right, front center, LFE, back left, back right, side left, side right

I.e. it officially does not support 2.1, 3.1, 4.1. at all! Weird. I have found out, that sometimes special metdata tag "WAVEFORMATEXTENSIBLE_CHANNEL_MASK" is used to redefine channel mapping, but it is very unofficial with poor support in decoders.

[jwhitworth]

That is weird.

My sound system is in storage right now. When I had it setup I did not have any 4.1 music. I may check on some other audio forums to see if 4.1 becomes a problem with channel assignment. I have never encountered any 3.1 music. I have only found the 3.0 on SACD's that were originally RCA Living Stereo LP's.