How to count PCM frames captured?

How to count PCM frames captured?

[Agata Ma]

Hi,

I'm new to ALSA programming so I hope you can excuse
me if I say
trivial things...
I have read various Alsa programming introduction
guides and
tutorial I found on Alsa-Project web site and
Googling...

http://www.suse.de/~mana/alsa090_howto.html
http://equalarea.com/paul/alsa-audio.html
http://www.linuxjournal.com/article/6735


My target is to build a simple C application to:

open interface to capture
set hardware parameters
while there is data to be processed:
	read pcm data
	count how many frames have been captured
	write only 1 frame every 1000 frames captured into a
file
close interface

Reading the programming guides I understand I have to
think in term of
frames.
So, my question is: does exist an ALSA function to
count the PCM frames
captured and moved to buffer?
If I'm not wrong the buffer is divided in periods and
each period
contain a number of frames.
So, the hypothetical PCM_FRAME_COUNT_FUNCTION should
work before the
frames are passed to the buffer..M'I wrong?
If the hypothetical PCM_FRAMES_COUNT_FUNCTION does not
exist, does exist
an hypothetical PCM_PERIODS_COUNT_FUNCTION?

I would like to point out that in my situation is not
important to be
precise to record on a file a frame every 1000.
The number 1000 is the lower threshold, so if the
program record on the
file a frame every 1023 or 10xx is not relevant to me.

I could work with a PCM_PERIODS_COUNT_FUNCTION if it
exist!

Can you suggest me some ideas and why not..if you
can..examples...

Thanks for your time and help
a newbie, Agata

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Re: How to count PCM frames captured?

[Clemens Ladisch]

Agata Ma wrote:
> So, my question is: does exist an ALSA function to count the PCM
> frames captured and moved to buffer?

The function snd_pcm_avail_update() returns how many frames are
available in the device's buffer.

The function snd_pcm_readi() returns how many frames it has copied to
your buffer.


HTH
Clemens

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Re: How to count PCM frames captured?

[Agata Ma]

Clemens Ladisch wrote:
> Agata Ma wrote:
>> So, my question is: does exist an ALSA function to
count the PCM
>> frames captured and moved to buffer?
> 
> The function snd_pcm_avail_update() returns how many
frames are
> available in the device's buffer.
> 
> The function snd_pcm_readi() returns how many frames
it has copied to
> your buffer.
> 
> 
> HTH
> Clemens
> 
> 
Hi Clemens,

Thanks for your suggestion, I have wrote a simple C
code using
snd_pcm_readi() and it work..I can count the frames..

Now, a new "problem" arise...but I'm going to open a
new thread to be
more precise.

Thanks
Agata



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