OpenAL Configuration

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[edit] About

This is a little writeup about the configuration of the OpenAL SI implementation which is used on Linux, BSD and others (MacOS/X and Windows have their own implementations which are different). Unfortunately there seems to be no documentation about how to configure ALSA yet, so we provide this as an interim solution.

[edit] Configuration File

OpenAL is first trying to read a user settings from an .openalrc in the users home directory if it exists ($HOME/.openalrc). If it can't be found then /etc/openalrc is used. If this also fails the following default settings apply: 

(define speaker-num 2)
(define display-banner #t)
(define source-gain 1.0)

This is from the source code, however there seems to be no code to handle display-banner and source-gain...

[edit] Settings

[edit] Format

The settings files are written in LISP (Wikipedia about LISP). Variables get defined with the define command. Example: 

(define somevar 5.0)
(define someStringVar "hello")
(define someList '(id1 id2 id3))

[edit] Examples

Normal Linux config, try ALSA and dsp, then fallback to arts and esd or no audio. Stereo sound in CD Quality (44,1khz): 

(define devices '(alsa native arts esd null))
(define alsa-device "default")
(define speaker-num 2)
(define sampling-rate 44100)

ALSA surround sound with a 5.1 sound system and 48khz high quality audio: 

(define devices '(alsa))
(define speaker-num 6)
(define alsa-out-device "surround51:0,0")
(define alsa-in-device "hw:0,0")
(define sampling-rate 48000)

[edit] General

  • devices contains a list of devices which are tried as OpenAL output devices. Possible values are:
    • dsp - OSS (Open Sound System) driver
    • native - Preferred driver for the platform (will load a driver for Darwin, morphos, Solaris, windows, BSD, ALSA or dsp)
    • alsa - ALSA (Advanced Linux Sound System) driver, only available on Linux
    • arts - ARTS, the KDE Sound Daemon
    • dmedia - DMEDIA, seems to be the irix sound api...
    • esd - ESD (Enlightenment Sound Daemon), often found on GNOME installations
    • sdl - SDL (Simple Direct Media Layer), uses the SDL library for sound output
    • null - NULL, no output
    • waveout - Writes to .wav files
  • direcion - unclear...
  • sampling-rate - The sample rate used for mixing and sound output
  • speaker-num - The number of speakers (2 for stereo speakers and headsets, 4,5,6 are supported on alsa for surround sound)
  • source-rolloff-factor - default rolloff factor ([1])
  • device-params - unclear...

[edit] ALSA Specific

  • alsa-device - The alsa device used for sound input and ouput (used when alsa-out-device or alsa-in-device is not defined)
  • alsa-out-device - The alsa device used for sound output
  • alsa-in-device - The alsa device used for sound input

[edit] OSS/DSP Specific

  • lin-dsp-path - Path to the audio device (default /dev/dsp)
  • lin-dsp-read-path - Path for audio output device

[edit] Irix - DMEDIA

  • dmedia-out-device
  • dmedia-in-device
  • dmedia-rear-out-device

[edit] MacOS/X - Darwin Specific

  • native-backend-debug - set to true for debugging
Retrieved from "http://supertux.lethargik.org/wiki/OpenAL_Configuration"
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