[alsa-devel] snd_pcm_set_params() bug?

[Takashi Iwai]

At Sat, 24 Jan 2009 11:53:14 +0100,
Cristian Morales Vega wrote:
> 
> 2008/6/2 Christian Morales Vega <cmorve69 at yahoo.es>:
> > This code:
> >
> > #include <alsa/asoundlib.h>
> >
> > int main(){
> >    snd_pcm_t *handle;
> >    if(snd_pcm_open(&handle, "default:1", SND_PCM_STREAM_PLAYBACK, 0) < 0) {
> >      exit(1);
> >    }
> >
> >    if(snd_pcm_set_params(handle, SND_PCM_FORMAT_S16_LE,
> > SND_PCM_ACCESS_RW_INTERLEAVED,
> >       2, 24000, 1, 100000) < 0) {
> >      exit(2);
> >    }
> > }
> >
> > fails with error "ALSA lib pcm.c:7193:(snd_pcm_set_params) Unable to
> > get period size for PLAYBACK: Invalid argument"
> > Disable resampling and you get "ALSA lib
> > pcm.c:7142:(snd_pcm_set_params) Rate doesn't match (requested 24000Hz,
> > get 0Hz)" (normal, I suppose). With other samplerates works fine.
> >
> > I'm using alsa-driver-kmp-default-1.0.16.20080602 and
> > alsa-1.0.16.hg20080510 RPM packages from multimedia:audio openSUSE
> > Build Service repository (from Takashi Iwai) and an AD1988 (hda-intel)
> > codec. A XUbuntu user also has the same problem with an hda-intel
> > codec (that I suppose uses stable 1.0.16).
> > With a SB Live! in the same computer there are no problems.
> >
> >
> > This was discovered with bsnes ( http://byuu.cinnamonpirate.com/bsnes/
> > - http://board.zsnes.com/phpBB2/viewtopic.php?t=11584 ) that can use
> > openal, libao or alsa directly. The problem just happens when using
> > 24KHz with alsa. So I suppose the problem is in the
> > snd_pcm_set_params() itself, since openal and libao have not the
> > problem but they set parameters "manually", not with
> > snd_pcm_set_params().
> >
> 
> The problem persists with alsa-1.0.19.git20090122-1.1 and
> alsa-driver-kmp-default-1.0.19.20090124_2.6.27.7_9.1-1.1 from openSUSE
> 11.1 multimedia:audio(:kmp) Build Service repository.
> 
> Note that the problem only happens with snd_pcm_set_params(). Using
> snd_pcm_hw_params_set_* functions works fine (and I really get 24KHz):
> http://board.zsnes.com/phpBB2/viewtopic.php?p=170478#170478

Hm, snd_pcm_set_params() is basically nothing but the command
sequences of snd_pcm_hw_params_*().  So, some call of them is
broken...


Takashi