Re: alsa hw params on SB Pro

[Takashi Iwai <tiwai@suse.de>]

At Mon, 7 Feb 2005 23:36:06 -0600,
Ryan Underwood wrote:
> 
> Hi,
> 
> I seem to have the following problem.  On snd-sb8 with a SBPro (which is
> capable of stereo), the best stereo playback mode is 22KHz - going above
> 22KHz implies that the output will be only one channel.
> 
> If I call snd_pcm_hw_params_set_channels_near with argument of 2
> channels, I get 2 channels as requested.  But then I call
> snd_pcm_hw_params_set_rate_near with argument of 44100, and have 44100
> returned.  Thus I end up with a hwparams that the hardware is not
> capable of.
> 
> Is there a reason the second call returns 44100 instead of 22050?
> Conversely, calling _set_rate_near first and having 44100 returned
> should mean that I only get 1 channel returned from _set_channels_near.
> Isn't this the point of _near functions after all?
> 
> This is with libasound 1.0.8 and drivers version 1.0.8+2 from debian
> (kernel 2.4.27).

Looking at sb8_main.c, the driver seems to try tighter the hw
constraint when channels=2 is set.  If this doesn't work, this might
be a bug of hw params configurator.


Takashi


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