how many processed frames? + various thoughts

how many processed frames? + various thoughts

[John John]

Hello all,
I'm rather new to ALSA development. I would like to build a little loop-player driven by a beat counter 
and a good mail exchange from linuxaudio.org gave me a smart solution: to count the beat bars into the 
audio thread. Knowing the sample rate and the processed samples, I'm able to calculate the clock (what do you 
think about this approach?). And now my question: is there a good function into alsa API which returns 
the number of processed frames? Or even better, is it possibile to fire a callback after N frames?
Thank you in advance (and sorry for my English)!

JJ
 		 	   		  

Re: how many processed frames? + various thoughts

[Clemens Ladisch]

John John wrote:
> Knowing the sample rate and the processed samples, I'm able to
> calculate the clock (what do you think about this approach?).

The sound card's clock will not be exactly synchronous with the
computer's clock.

> is there a good function into alsa API which returns the number of
> processed frames?

snd_pcm_writei() does return the number of processed frames.

snd_pcm_delay() returns the offset to the position of the sample that is
currently being played.


Regards,
Clemens