OpenAL

Introduction

OpenAL is a cross-platform 3D audio library, it is used mainly in audio applications & games. i.e ut2004 & TaSpring. Unfortunaly OpenAL defaults to OSS for sound playback if its not configured & told to use something else i.e ALSA.

Which config file to use

There are 2 different places for the config file for OpenAL

1. /etc/openalrc is for system wide setup
2. ~/.openalrc is for user specific setup

Configuring OpenAL

To comment lines # = text  ; = options

 (define devices '(alsa))
 (define devices '(alsa esd arts sdl null))

1. First line is just tellin OpenAL to use alsa
2. Second line tells OpenAL to use alsa, if that fails it falls back to esd and so on.

• OpenAL uses ESPEAKER environment var (should be set to HOST[:PORT]) to determine esd server to connect to.

 # Sound Output
 (define alsa-out-device default)
 (define alsa-out-device "hw:0,0")

 # Sound Input i.e microphone
 (define alsa-in-device default)
 (define alsa-in-device "hw:0,0")

1. If u only have one soundcard use the first line(s). It tells openal to use default soundcard for output | input.
2. Second Line(s) specifc tell OpenAL which soundcard to use. i.e u got more than one soundcard
   1. ( Use aplay -l for find out soundcard numbers i.e hw0:0 )

 # 2 Speaker setup
 (define speaker-num 2)

 # 4 Speaker surround with ALSA
 (define speaker-num 4)
 (define alsa-out-device "surround40:0,0")

 # 6 Speaker surround with ALSA
 (define speaker-num 6)
 (define alsa-out-device "surround51:0,0")

• Note that the alsa-out-device line is different if using surrond sound setup than shown previously

(define display-banner #t)
(define source-gain 1.0)
(define sampling-rate 44800)

These options are also avaible according to the source code.

Example

Below is example of /etc/openalrc. Its setup to use Alsa & default soundcard & 2 speakers

 (define devices '(alsa))
 (define alsa-out-device default)
 (define alsa-in-device default)
 (define speaker-num 2)