fgdata/Docs/README.sound

OpenAL setup for general use (Linux)
-------------------------------------
As of the July 2004 release of OpenAL it is best to add at least the
following line to your ~/.openalrc file on Linux because it wil find out
what audio backend to use, starting with the most appropriate:

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



ALSA surround sound (5.1) setup
-------------------------------------
(taken from http://floam.ascorbic.com/how-to/alsa5.1)

Make a ~/.openalrc, we are telling OpenAL that we want surround sound and
we want to use ALSA instead of OSS.

(define speaker-num 4)
(define devices '(alsa))
(define alsa-out-device "surround40:0,0")



IRIX surround sound (5.1) setup
-------------------------------------
To add 4 channel surround sound on IRIX hardware that supports in
directly you can just add the following line to your ~/.openalrc file:

(define speaker-num 4)

To add 4 channel surround sound to IRIX systems that have more than one 
stereo output you can add the following section to your ~/.openalrc file
(for a typical O2 configuration):

(define speaker-num 4)
(define native-out-device "Analog Out")
(define native-rear-out-device "Analog Out 2")

or alternatively:

(define speaker-num 4)
(define native-out-device "A3.Speaker")
(define native-rear-out-device "A3.LineOut2")



(Note the following section is obsolete as of the July 2004 release of 
OpenAL, since your could command OpenAL to use ALSA or Arts directly)

ALSA and Arts
-------------------------------------

I'm using kernel 2.6.5 with alsa, my sound module is snd-intel8x0. When I ran
fgfs, I'd get quite 'choppy' sound (wasn't smooth, there'd be a couple of
breaks in the sound every second or so). Running arts, and starting fgfs with
"artsdsp fgfs" (from the artsdsp website: "When an application is run under
artsdsp all accesses to the /dev/dsp audio device are intercepted and mapped
into aRts API calls. While the device emulation is not perfect, most
applications work this way, albeit with some degradation in performance and
latency.") would improve the situation, but it seemed to still be choppy.

This command:
echo "fgfs 0 0 direct" >/proc/asound/card0/pcm0p/oss

(from the alsa kernel OSS emulation website:
  "The direct option is used, as mentioned above, to bypass the automatic
   conversion and useful for MMAP-applications")

made my sound work beautifully when fgfs was run with artsdsp. Running without
artsdsp however (with artsd suspended or killed), would give me no sound at all
(which I find a bit strange)

The following websites might help people with similar troubles:
http://www.alsa-project.org/~iwai/OSS-Emulation.html
http://www.arts-project.org/doc/handbook/artsdsp.html

Computer info:

kernel 2.6.5

flightgear 0.9.4
simgear 0.3.5
plib 1.8.3

soundcard is onboard an asus p4p800-e deluxe mobo (using snd-intel8x0), alsa,
related modules from lsmod:
Module                  Size  Used by
snd_pcm_oss            53252  1
snd_mixer_oss          19968  1 snd_pcm_oss
snd_intel8x0           33476  1
snd_ac97_codec         63492  1 snd_intel8x0
snd_pcm                97408  2 snd_pcm_oss,snd_intel8x0
snd_timer              26112  1 snd_pcm
snd_page_alloc         11396  2 snd_intel8x0,snd_pcm
snd_mpu401_uart         7936  1 snd_intel8x0
snd_rawmidi            24832  1 snd_mpu401_uart
snd_seq_device          8324  1 snd_rawmidi
snd                    53892  9 snd_pcm_oss,snd_mixer_oss,snd_intel8x0,snd_ac97_codec,snd_pcm,snd_timer,snd_mpu401_uart,snd_rawmidi,snd_seq_device
soundcore              10208  2 snd