[Openal] Openal, S/PDIF and surround

[Chris Robinson]

Hi Alfredo.

After some quick searching around, it seems ALSA has an a52 plugin that can 
encode a surround sound stream to pass-through an S/PDIF output.

http://alsa-project.org/main/index.php/A52_plugin

As far as I can understand, when you have ALSA built with A52 support, you'd 
tell OpenAL to use the 'plug:a52' device, with 6 channel output.

However, at that last point, I should ask what version of OpenAL are you 
using? OpenAL SI (v0.0.8, used by default in most package managers) does not 
do 5.1 output. If you're using that, you may have to create a plugin with 
~/.asoundrc that maps a 4 channel device onto a 6 channel slave, however, it 
would be better to use the newer OpenAL Soft, which does natively support 5.1 
output.