pcm-capture-threshold-test.c

pcm-capture-threshold-test.c

#include <stdio.h>
#include <stdlib.h>

#include <string.h>
#include <errno.h>

#include <poll.h>

#include <alsa/asoundlib.h>

#ifdef PULSE
 #define NODE	"pulse"
#else
 #define NODE	"hw:1,0"
#endif

int main(int argc, const char *const *argv)
{
	snd_pcm_t *handle;
	int pfd_count;
	struct pollfd *pfds;
	snd_pcm_uframes_t frame_count;
	int err;

	err = snd_pcm_open(&handle, NODE, SND_PCM_STREAM_CAPTURE, 0);
	if (err < 0) {
		printf("snd_pcm_open(): %s\n", strerror(-err));
		return EXIT_FAILURE;
	}

	pfd_count = snd_pcm_poll_descriptors_count(handle);
	if (pfd_count < 0) {
		printf("snd_pcm_poll_descriptors_count(): %s\n",
		       strerror(-pfd_count));
		goto end;
	}

	pfds = calloc(pfd_count, sizeof(*pfds));
	if (pfds == NULL) {
		printf("calloc(2): %s\n", strerror(errno));
		goto end;
	}

	err = snd_pcm_poll_descriptors(handle, pfds, pfd_count);
	if (err < 0) {
		printf("snd_pcm_poll_descriptors(): %s\n", strerror(-err));
		goto err_pfds;
	}

	err = snd_pcm_set_params(handle, SND_PCM_FORMAT_S16,
				 SND_PCM_ACCESS_RW_INTERLEAVED,
				 2, 48000, 0, 100 * 1000);
	if (err < 0) {
		printf("snd_pcm_set_params(): %s\n", strerror(-err));
		goto err_pfds;
	}

	{
		snd_pcm_sw_params_t *sw_params;

		err = snd_pcm_sw_params_malloc(&sw_params);
		if (err < 0) {
			printf("snd_pcm_sw_params_malloc(): %s\n",
			       strerror(-err));
			goto err_pfds;
		}
		err = snd_pcm_sw_params_current(handle, sw_params);
		if (err < 0) {
			printf("snd_pcm_sw_params_current(): %s\n",
			       strerror(-err));
		} else {
			err = snd_pcm_sw_params_get_start_threshold(sw_params,
								&frame_count);
			if (err < 0)
				printf("snd_pcm_sw_params_get_start_threshold: %s\n",
				       strerror(-err));
			printf("start_threshold: %lu\n", frame_count);
		}
		snd_pcm_sw_params_free(sw_params);
		if (err < 0)
			goto err_pfds;
	}

	//err = snd_pcm_start(handle);
	//if (err < 0) {
	//	printf("snd_pcm_start(): %s\n", strerror(-err));
	//	goto err_pfds;
	//}

	//frame_count /= 2;

	while (1) {
		int count;
		unsigned short revents;
		char buf[16 * 2 * frame_count];
		snd_pcm_sframes_t handled_frame_count;

		handled_frame_count = snd_pcm_readi(handle, buf, frame_count);
		if (handled_frame_count < 0) {
			err = -handled_frame_count;
			printf("snd_pcm_readi(): %s\n", strerror(-err));
			break;
		}
		printf("handled: %lu\n", handled_frame_count);

		count = poll(pfds, pfd_count, frame_count / 48000);
		if (count < 0) {
			if (errno == EINTR || errno == EAGAIN)
				continue;
			err = errno;
			break;
		}
		if (count == 0)
			continue;

		err = snd_pcm_poll_descriptors_revents(handle, pfds, pfd_count,
						       &revents);
		if (err < 0)
			break;
	}

err_pfds:
	free(pfds);
end:
	snd_pcm_close(handle);

	return EXIT_SUCCESS;
}