Andy Furniss wrote:
Moritz Barsnick wrote:
On Wed, Sep 16, 2015 at 05:38:30 +0800, Rick C. wrote:
Output #0, dvd, to '/Users/mahalko/Desktop/output.vob':
[...]
Stream #0:1: Audio: ac3, 0 channels, 128 kb/s
And I'm not sure I understand the concept of zero channel audio
streams. ;-)
There are valid uses in wav at least though ffmpeg doesn't like
them.
The case I am thinking of is ambisonic formats where 0 channels
indicates not for speakers (I beleive DTS and MPEH-H can also handle
this).
Having had more time to remember old tests and look at the wav spec I
think that what was 0 was the dwChannelMask in the wav.
From the microsoft site
http://msdn.microsoft.com/en-us/windows/hardware/gg463006.aspx
If, for example in a multi-channel audio authoring application, no
speaker location is desired on any of the mono streams, the
dwChannelMask should explicitly be set to 0. 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.
This also means that if the device doesn't know how to process the raw
audio streams, it should not accept the multi-channel stream with a
dwChannelMask of 0. A device like a digital mixer or a digital audio
storage device (hard disk, ADAT, and so on) might want to accept formats
without particular speaker locations.
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