i810 & wineoss & sound formats

Francois Gouget fgouget at codeweavers.com
Mon Nov 4 04:35:02 CST 2002

There is something that sees very wrong in OSS_WaveOutInit. We do:

     smplrate = 44100;
     if (ioctl(ossdev->fd, SNDCTL_DSP_SPEED, &smplrate) == 0) {
         ... this format is supported ...

But according to the OSS spect this ioctl call is not garanteed to give 
you the actual sampling frequency you asked for. So if the device only 
supports 11025Hz, ioctl will return success but you will find that after 
the call smplrate==11025.

So it seems it would be more correct to do:

     smplrate = 44100;
     if (ioctl(ossdev->fd, SNDCTL_DSP_SPEED, &smplrate) == 0 &&
         smplrate==44100) {
         ... this format is supported ...

There are other issues like you cannot assume that because a sound card 
supports 44100Hz in mono it supports it in stereo. It might only support 
stereo up to 22050Hz. Same thing with 8 bits vs. 16 bits. That's for old 
cards though, with modern cards it's the opposite. Some cards, e.g. 
based on the i810 chipset, support 48000Hz in 16 bit in stereo but 
nothing else, not 48000Hz in 16 bit in mono for instance.

So assuming we do strict checks (I have code for that), for an i810 card 
waveOutGetDevCaps should return:

0: "CS4236/37/38" 1.0 (255:1): channels=2 formats=0000 support=006c

I.e. none of the formats at 11025, 22050 or 44100 are supported. But 
testing this on Windows I get:

0: "YAMAHA AC-XG WDM Audio" 5.10 <1:100>: channels=65535 formats=bfff 

Which leads me to the following questions:
  * should waveOutGetDevCaps consider that a format is supported as long 
as we can up-sample to a format that is?
  * what does the b mean in 'formats=bfff'? I could not find any 

(the support=006c vs. 002c is not significant, it's just 

Francois Gouget
fgouget at codeweavers.com

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