[openal] Use OpenAL to playback to specific channel

[Chris Robinson]

On 05/23/2017 09:31 AM, John Lee wrote:
> I'd love to be able to create "virtual" OpenAL devices that map to
> specific ALSA PCMs. Is that possible?

Not in 1.17 unfortunately. But I did just add a config option to the 
current git version. In ~/.alsoftrc or ~/.config/alsoft.conf, you can 
specify:

[alsa]
custom-devices = Stereo Set 1=setA;Stereo Set 2=setB

The format is <OpenAL device name>=<ALSA device name>, with each entry 
separated by semicolons (note that pre- and post-spaces are preserved, 
not stripped). These add to the list of devices that are normally 
provided, and appear after the ALSA Default device. It also doesn't 
currently verify that the ALSA device is actually valid, the related 
OpenAL device will just fail to open if it's not.