* how many processed frames? + various thoughts
@ 2010-09-30 18:49 John John
2010-10-01 7:03 ` Clemens Ladisch
0 siblings, 1 reply; 2+ messages in thread
From: John John @ 2010-09-30 18:49 UTC (permalink / raw)
To: alsa-devel
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
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: how many processed frames? + various thoughts
2010-09-30 18:49 how many processed frames? + various thoughts John John
@ 2010-10-01 7:03 ` Clemens Ladisch
0 siblings, 0 replies; 2+ messages in thread
From: Clemens Ladisch @ 2010-10-01 7:03 UTC (permalink / raw)
To: John John; +Cc: alsa-devel
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
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2010-09-30 18:49 how many processed frames? + various thoughts John John
2010-10-01 7:03 ` Clemens Ladisch
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