Re: Trying to understand alsa

[Andrew Eikum <aeikum@codeweavers.com>]

On Thu, Jan 12, 2012 at 11:16:47PM +0000, Jonathan Andrews wrote:
> On Thu, 2012-01-12 at 16:12 -0600, Andrew Eikum wrote:
> > On Thu, Jan 12, 2012 at 09:44:11PM +0000, Jonathan Andrews wrote:
> > > I have an application that works using 512 sample packets of 22050Hz 16
> > > bit mono audio.  The 'receiver' takes many audio streams from a network
> > > via UDP, at the moment it pipes them into pulse.
> > > 
> > > Can alsa buffer audio. At the moment every time I and set an audio
> > > buffer size I get a negative response from
> > > snd_pcm_hw_params_set_buffer_size .  I'm somewhat confused about the
> > > units alsa uses ...
> > > 
> > 
> > You don't want to over-specify your requirements. You require a buffer
> > size of "at least" 3 * 512 frames. So use set_buffer_size_min().
> 
> I cant find any reference to "set_buffer_size_min" in the ALSA API
> documentation I have or the link you provided ?
> snd_pcm_hw_params_set_buffer_time_near() is the closest and that seems
> to take an argument in useconds.  
> ?
> http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m.html
> 

The doxygen docs are split strangely. The function is documented here:
http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m___h_w___params.html#gb8d160039ffbbb15cb7187aa9ffae462

I find keeping the alsa-lib source on hand for quick grepping is often
helpful.

Andrew