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Multichannel Channel Order
post Dec 12 2011, 22:21
Post #1

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Member No.: 94046

I've found that the option "--channel-order=" only works with raw PCM.

I had a 5 channel WAV (FL,FR,LFE,BL,BR) that I encoded. I then used "wvunpack -s foo.wv" and got back "channels: 5 (unassigned speakers)"

I wanted to have the channels assigned so
wavpack --channel-order=FL,FR,LFE,BL,BR foo.wav
and got back "this WAV file already has channel order information!"

I converted the WAV to raw PCM then
wavpack --channel-order=FL,FR,LFE,BL,BR foo.raw --raw-pcm=48000,24,5
which worked.

Is the option "--channel-order=" supposed to work like this?
I would think it's counter-intuitive that one couldn't change the channel order of a WAV file with the "--channel-order=" option.


It was actually a WAVEX if that makes any difference.

This post has been edited by xslig: Dec 12 2011, 22:37
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post Dec 14 2011, 09:03
Post #2

Group: Developer
Posts: 657
Joined: 22-November 10
From: Japan
Member No.: 85902

Wow, when it comes to interpretation of spec written by English, it's too difficult to me.
A dwChannelMask of 0 tells the audio device to render the first channel to the first port on the device, the second channel to the second port on the device, and so on.
To me, it looks like saying that as long as the same audio device and same configuration is in use, the result of dwChannelMask of 0 is completely deterministic, and it will be rendered/mapped in the device port order. However,
Having nChannels exceed the number of bits set in dwChannelMask can produce inconsistent results and should be avoided if possible.
This is inconsistent because wave file itself doesn't define the asignment, but asignment is defined by the device configuration (in other word, it's device dependent).
I don't know if this can be said channel layout/asignment is defined or not.

Anyway, Windows Media Player, foobar2000, winamp seems to treat wave files with dwChannelMask 0 by it's implicit default order (probably exactly the same way as if it were not WAVEFORMATEXTENSIBLE).
6 channel wav seems to be interpreted as FL FR FC FLE BL BR by them.
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