[SDL] Blocking ALSA

[Philip Boulain]

Hello,

I'm using libSDL 1.2.7 on Gentoo. I have SDL_AUDIODRIVER set to "alsa", 
and am using the ALSA sound system in kernel 2.6.3. ALSA is set up to 
use dmix on the "default" device. As a result, I can play multiple sound 
streams from multiple alsaplayers and XMMS happily.

However, SDL appears to engage in blocking behaviour, even though the 
changelog shows this being fixed in 1.2.6. For example, if I try to 
start FreeCiv (a SDL game) while playing music in XMMS:

   ALSA lib pcm_hw.c:1055:(snd_pcm_hw_open) open /dev/snd/pcmC0D0p 
failed: Device or resource busy
   ALSA lib pcm_dmix.c:812:(snd_pcm_dmix_open) unable to open slave
   1: Error calling Mix_OpenAudio
   1: Plugin sdl found but can't be initialized.
   2: Proceeding with sound support disabled

Conversely, if I start it with nothing else playing, sound works fine, 
but other applications are 'locked out' from playing sound. Similar 
behaviour is demonstratable with other SDL apps, like BZFlag.

Why does SDL behave this way? Is it by design (Why? It's quite 
annoying), or is it a bug?

Philip "LionsPhil" Boulain