Re: [alsa-devel] Buffer size calculation based on period size

noman pouigt wrote:

I am using tinycap to capture the audio and setting below settings: bitwidth = 16 rate = 16000 channel = 1 period_size = 320 period_count = 2

I am wondering how is below period_size and buffer_size calculated?

Shouldn't period_size of 320 bytes and period_count of 2 fail?

From the tinyalsa source code:

param_set_min(&params, SNDRV_PCM_HW_PARAM_PERIOD_SIZE, config->period_size);

So it uses either the supplied value, or if that is too small, the smallest allowed value.

cat sub0/hw_params

access: RW_INTERLEAVED format: S16_LE subformat: STD channels: 1 rate: 16000 (16000/1) period_size: 2042 buffer_size: 4084

The actual values of period_size and period_count are returned by pcm_open().

Regards, Clemens