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-   -   6 channels mapped different than wav (https://forum.musepack.net/showthread.php?t=594)

Antonski 20 June 2009 02:53 pm

6 channels mapped different than wav
 
Hi guys,

I found some 6 ch. wav files and tried to convert to mpc just to prove that it can work with multichannel audio.
However, it appeared, that FR and FC are swapped, if in wave file they are ordered as FR FC FR (BL BR LFE), in mpc they are played as FR FR FC.
I cannot hear the back channels (BL and BR) and LFE on my laptop, so I cannot say if there is an issue with their order too.
I don't know if there is a standard for channels order and if there is some markers in the wav, but I expected that decoded channels should be in the same order as in the input signal, maybe it's not so simple though.
The second issue with multichannel audio is that back and front channels are mixed, so in mpc file I can hear both FL and BL from the left speaker, while in the original wav I can hear only the FL.
I tried Foobar2000 and MusicBee (using bass library), both sounds the same way.
I cannot attach the test wavs, they are bigber than the limit, so I uploaded them here:

test1
test2

Regards,
Tony

Antonski 20 June 2009 11:29 pm

Hello again,

with a little googling I found the following about 5.1channel mappings:

5.1 WAV: FL , FR , FC , LFE, SL , SR
5.1 AC3: FL , FC , FR , SL , SR , LFE
5.1 DTS: FC , FL , FR , SL , SR , LFE
5.1 AAC: FC , FL , FR , SL , SR , LFE
5.1 AIFF: FL , SL , FC , FR , SR , LFE

I believe the channel mapping must be standardized for musepack as well. Maybe the easiest way would be to accept the Microsoft's convention because musepack files are coded from wav anyway?
Maybe it would be good to have also advanced switch for declaring of the input channel mapping?

BTW, the test files in my previous post might be wrong, I decoded them from test wma and ogg files. I tried the Microsoft's 5.1/7.1 test files but mpcenc does not recognize them, although they seems to be OK for foobar :|

Quote:

Foobar2000:
File Name : 8_Channel_ID.wav
Folder Name : D:\TestSamples\8chan\MS
File Path : D:\TestSamples\8chan\MS\8_Channel_ID.wav
Subsong Index : 0
File Size : 15.3MB (16 126 124 bytes)
Last Modified : 2005-02-04 10:54:38
Duration : 0:13.998 (671919 samples)
Sample Rate : 48000 Hz
Channels : 8
Bits Per Sample : 24
Bitrate : 9216 kbps
Codec : PCM
Encoding : lossless
Code:

MPC Encoder 1.30.0 --stable-- (C) 1999-2009 Buschmann/Klemm/Piecha/MDT
Built Feb 26 2009 20:33:36
 ERROR: WAVE file has no linear PCM format!

ERROR: Invalid file header, not a WAVE file '8_Channel_ID.wav'

Quote:

Foobar2000:
File Name : 6_Channel_ID.wav
Folder Name : D:\TestSamples\6chan\MS
File Path : D:\TestSamples\6chan\MS\6_Channel_ID.wav
Subsong Index : 0
File Size : 2.94MB (3 089 060 bytes)
Last Modified : 2002-09-23 12:45:34
Duration : 0:05.837 (257411 samples)
Sample Rate : 44100 Hz
Channels : 6
Bits Per Sample : 16
Bitrate : 4233 kbps
Codec : PCM
Encoding : lossless
Code:

MPC Encoder 1.30.0 --stable-- (C) 1999-2009 Buschmann/Klemm/Piecha/MDT
Built Feb 26 2009 20:33:36
 ERROR: WAVE file has no linear PCM format!

ERROR: Invalid file header, not a WAVE file '6_Channel_ID.wav'


Shy 04 July 2009 04:07 pm

Hi Tony. This reply is pretty late, but I just want to say we did notice what you said and we'll try to address it (hopefully r2d's computer will get fixed soon :)). Multichannel handling is a global mess and our encoder will also have to be changed to recognize MS's messy "extensible" wave format. And we'll see about finalizing a strict mapping of 3 to 8 channels for Musepack.


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