quit snd_pcm_readi, retrieve pending frames

[Gerald Grabner <gerald.grabner@gmx.net>]

Hi,

I'm experimenting with the ALSA PCM API and was wondering whether
there is a simple way to exit a record loop by stopping the pcm, but
without loosing pending frames.

Initially, I was thinking of something like this, where I would call
snd_pcm_drop(pcm) from some other thread:

   while ( true )
     {
       r = snd_pcm_readi (pcm, data, frames);
       fwrite (data, 2, 2*r, file);
       if ( r != frames )
         break;
     }

However, snd_pcm_drain(pcm) doesn't work here; the loop continues.
snd_pcm_drop(pcm) breaks the loop, but pending frames are lost, and
r=-EBADFD.

Is there an easy way to stop snd_pcm_readi in a way that I can
retrieve the residual frames? Do I need to set any parameters for
that purpose?

Many thanks,
Gerald

BTW: I'm using alsa 1.0.11 on gentoo.


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