[alsa-devel] Is snd_pcm_hw_params_set_period_time_near the same as sampling period?
Hi mates.
I am trying to understand a piece of a code I am studing . What does exactly the functions snd_pcm_hw_params_set_period_time_near sets?
In my understand period time should be the time between 2 consecutive samples, but the following code does not appears to be calculating that.
buffer_time = 500000 // What I believe that means 0.5s as US is the unit used.
if (period_time == 0 && period_frames == 0) { if (buffer_time > 0) period_time = buffer_time / 4; else period_frames = buffer_frames / 4; }
Is this period time the same as period describled in here:
http://www.fon.hum.uva.nl/praat/manual/sampling_period.html
Thanks!
Guilherme Longo wrote:
I am trying to understand a piece of a code I am studing . What does exactly the functions snd_pcm_hw_params_set_period_time_near sets?
The period time.
In my understand period time should be the time between 2 consecutive samples,
In ALSA, a period is the interval between consecutive interrupts from the sound card; this is the same as a fragment in OSS.
When the application tries to write/read more than than would be available, ALSA waits until the next period boundary before checking again.
HTH Clemens
participants (2)
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Clemens Ladisch
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Guilherme Longo