[alsa-devel] period_size and .asoundrc

[Takashi Iwai]

At Mon, 25 May 2009 15:12:17 +0200,
Canella Matteo wrote:
> 
> Hi everybody,
> I'm writing a little software that play a tone on a pcm device.
> In the hw param initialization I'm hardcoding the "periods" and "period_size" values:
> 
>                 unsigned int periods = 4;
>                 if (snd_pcm_hw_params_set_periods_near(buzzer_device.pcm_handle, buzzer_device.hwparams, &periods, 0) < 0) {
>                                fprintf(stderr, "Error setting periods.\n");
>                                return 1;
>                 }
>                 ///* set the period time */
>                 period_size = 8192;
>                 err = snd_pcm_hw_params_set_period_size_near(buzzer_device.pcm_handle, buzzer_device.hwparams, &period_size, 0);
>                 if (err < 0) {
>                                printf("Unable to get period size for playback: %s\n", snd_strerror(err));
>                                return err;
>                 }
> 
> I'd like to read this parameter form the .asoundrc file, so I'm wondering if there were API that does this task.

You can call snd_config_search() with snd_config as root config.
For example,

	snd_config_t *n;
	long val;
	if (snd_config_search(snd_config, "YOUR.CONFIG", &n) < 0)
		error();
	if (snd_config_get_integer(n, &val) < 0)
		error();

Takashi