Re: [Qemu-devel] [PATCH 0/5] audio: multi channel audio support

[Gerd Hoffmann]

  Hi,

> Currently you have to specify the number of channels you want to use
> when creating the usb-audio device, see the last commit for details.
> To do this I currently dynamically allocate the whole USBDesc structure,
> which looks ugly.  If there's a better way, please let me know!

You can have multiple USBDesc stuctures defined and pick one at device
initialization time (see hw/usb/dev-hid.c, there are usb 1.1 and usb 2.0
versions of all hid devices).

For usb-audio I think we need two: the current one (stereo) and a new
one with stereo + 5.1 and 7.1 support.  Then for the new one have 4
alternative interface configurations (off, stereo, 5.1, 7.1) instead of
only two (off, stereo).  Or possibly we need 3 interfaces (stereo, 5.1,
7.1) with on and off alternatives for each of them.  Didn't check
usb-audio spec.

cheers,
  Gerd