Re: [Protux-devel] [Fwd: Re: [Alsa-devel] available sampling rate detection]

[Martin Herren]

Martin Herren wrote:

> At Tue, 11 Feb 2003 08:53:59 +0100,
> Martin Herren wrote:
>
> > Hej,
> >
> > i'm new on this list as well as to alsa.
> >
> > We need to find out the supported sampling rates (and other 
> > parameters) for the pcm devices of soundcards.
> >
> > We used snd_pcm_hw_params_test_rate() for this, which according to 
> > the documentation 
> > (http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m___h_w___params.html#a53) 
> >
> > should return 1 if the rate is available, 0 otherwise.
> > The problem is that it always returned an non-null value, for any 
> > rate even if we knew it wasn't supported.
> >
> > Then we found out that we need to call snd_pcm_hw_params_any() first, 
> > and then snd_pcm_hw_params_test_rate() returns 0 for supported rates, 
> > and a negativ value (-22) otherwise.
>
>
> the documentation is wrong.  the test functions return zero if
> supported and a negative value if not supported, as well as the set
> functions do.
>
>
> Takashi 


i changed the three snd_pcm_hw_params_test_...()==0 to != 0 and added 
snd_pcm_hw_params_any() before the first test. MustuxAudioDeviceMapper 
seems now to recognise correctly the interfaces. I removed the comments 
around the format test, as if works fine for me too...

But even if MustuxAudioDeviceMapper seems to detect correctly the 
capabilities of the interfaces, BusSelector still let me select buses 
that's don't support 44.1kHz (like my digital out), and don't allow me 
to select 'legal' buses, like my SB16 in...

i didn't commit any changes to cvs, but here's my patch for 
MustuxAudioDeviceMapper.cc:

address@hidden:~/mustuxlib$ cvs diff MustuxAudioDeviceMapper.cc
Index: MustuxAudioDeviceMapper.cc
===================================================================
RCS file: /cvsroot/mustux/mustuxlib/MustuxAudioDeviceMapper.cc,v
retrieving revision 1.36
diff -r1.36 MustuxAudioDeviceMapper.cc
667a668,669
>       if (snd_pcm_hw_params_any(pcmHandle, tempHwParams) < 0)
>               return ERROR_CANNOT_OPEN_BUS; // would need its own 
error code
669c671
<         if (snd_pcm_hw_params_test_rate     (pcmHandle, tempHwParams, 
pRate, 0)==0)
---
>         if (snd_pcm_hw_params_test_rate     (pcmHandle, tempHwParams, 
pRate, 0)!=0)
674,675c676,677
< /* UNCOMMENT ME ...  THIS IS CRASHING !!! WHY ???
<      if (snd_pcm_hw_params_test_format   (pcmHandle, tempHwParams, 
format)==0)
---
> /* UNCOMMENT ME ...  THIS IS CRASHING !!! WHY ??? */
>      if (snd_pcm_hw_params_test_format   (pcmHandle, tempHwParams, 
format)!=0)
681,682c683,684
< */
<         if (snd_pcm_hw_params_test_channels (pcmHandle, tempHwParams, 
pChannels)==0)
---
>
>         if (snd_pcm_hw_params_test_channels (pcmHandle, tempHwParams, 
pChannels)!=0)