[openal] Speaker test

[Chris Robinson]

On 04/28/2017 10:07 AM, Anders Genell wrote:
> Well, when queing buffers and applying spatialization OpelAL-soft
> uses whatever backend there is (Alsa in our case) and does panning
> over the number of speakers defined in alsoft.conf, right?

Kind of. The channel configuration set in alsoft.conf is just a hint, 
and if it can't be set, OpenAL Soft will automatically try to set 
anything else that can work. Also, some configurations don't deal 
directly with speakers, like Ambisonics/B-Format which is a 
speaker-agnostic representation of 3D sound.

> Would it be possible to bypass the panning and just play buffers
> straight to one speaker/channel at a time?

You can bypass the panning, but only for playing specific (non-mono) 
buffer formats. You can't cycle through individual output channels since 
OpenAL doesn't expose the output configuration... you can only cycle 
through individual buffer channels that may or may not have a 
corresponding output channel.

> I guess a workaround would be to position a sound source at the exact
> angle where a speaker is placed according to alsoft.conf?

alsoft.conf doesn't specify the speaker placement. OpenAL Soft itself 
doesn't even know the speaker placement, but instead uses ambisonic 
decoder coefficients which correspond to particular layouts for the 
various configurations.