[SDL] alsa and DMA..

Stephane Marchesin stephane.marchesin at wanadoo.fr
Mon Jan 31 15:50:16 PST 2005


Dave Airlie wrote:

>>>What problems are therre with the current alsa backend?
>>>
>>The problem seems specific to ac97 cards (I have one, and other ac97
>>owners reported sound issues too), but I'm not sure.
>>
>
>have you a link to a report or two, I'm seeing the odd wierd thing but
>I've so far blamed it all on my hardware (the hardware guy can't prove
>it :-), I've had an issue with using different channels in SDL_mixer
>with my system...
>
There's no report of the problem on alsa, since the oss backend has 
priority over the alsa one (and alsa provides oss emulation, so it's 
almost always used).
That said, you can google for the infamous "SDL_DSP_NOSELECT" env variable.

If you have an ac97, the only way to get it to work is  to use an SDL 
that is more that 4 months old (not any recent CVS where this env 
variable has disappeared) with the oss backend (the dsp one, not the dma 
one) and set the SDL_DSP_NOSELECT variable.

I can't speak for SDL_mixer since I don't use/know it.

Stephane







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