alsa_test.c

/*
 *  Latency test program
 *
 *     Author: Jaroslav Kysela <perex@perex.cz>
 *
 *     Author of bandpass filter sweep effect:
 *	       Maarten de Boer <mdeboer@iua.upf.es>
 *
 *  This small demo program can be used for measuring latency between
 *  capture and playback. This latency is measured from driver (diff when
 *  playback and capture was started). Scheduler is set to SCHED_RR.
 *
 *
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sched.h>
#include <errno.h>
#include <getopt.h>
#include <alsa/asoundlib.h>
#include <sys/time.h>
#include <math.h>

char *pdevice = "plughw:0,0";
char *cdevice = "plughw:0,0";
snd_pcm_format_t format = SND_PCM_FORMAT_S16_LE;
int rate = 8000;
int channels = 1;
int buffer_size = 0;		/* auto */
int period_size = 0;		/* auto */
int latency_min = 0;		/* in frames / 2 */
int latency_max = 2048;		/* in frames / 2 */
int loop_sec = 90;		/* seconds */
int block = 0;			/* block mode */
int use_poll = 0;
int resample = 1;
unsigned long loop_limit;

snd_output_t *output = NULL;

int setparams_stream(snd_pcm_t *handle,
		     snd_pcm_hw_params_t *params,
		     const char *id)
{
	int err;
	unsigned int rrate;

	err = snd_pcm_hw_params_any(handle, params);
	if (err < 0) {
		printf("Broken configuration for %s PCM: no configurations available: %s\n", snd_strerror(err), id);
		return err;
	}
	err = snd_pcm_hw_params_set_rate_resample(handle, params, resample);
	if (err < 0) {
		printf("Resample setup failed for %s (val %i): %s\n", id, resample, snd_strerror(err));
		return err;
	}
	err = snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);
	if (err < 0) {
		printf("Access type not available for %s: %s\n", id, snd_strerror(err));
		return err;
	}
	err = snd_pcm_hw_params_set_format(handle, params, format);
	if (err < 0) {
		printf("Sample format not available for %s: %s\n", id, snd_strerror(err));
		return err;
	}
	err = snd_pcm_hw_params_set_channels(handle, params, channels);
	if (err < 0) {
		printf("Channels count (%i) not available for %s: %s\n", channels, id, snd_strerror(err));
		return err;
	}
	rrate = rate;
	err = snd_pcm_hw_params_set_rate_near(handle, params, &rrate, 0);
	if (err < 0) {
		printf("Rate %iHz not available for %s: %s\n", rate, id, snd_strerror(err));
		return err;
	}
	if ((int)rrate != rate) {
		printf("Rate doesn't match (requested %iHz, get %iHz)\n", rate, err);
		return -EINVAL;
	}
	return 0;
}

int setparams_bufsize(snd_pcm_t *handle,
		      snd_pcm_hw_params_t *params,
		      snd_pcm_hw_params_t *tparams,
		      snd_pcm_uframes_t bufsize,
		      const char *id)
{
	int err;
	snd_pcm_uframes_t periodsize;

	snd_pcm_hw_params_copy(params, tparams);
	periodsize = bufsize * 2;
	err = snd_pcm_hw_params_set_buffer_size_near(handle, params, &periodsize);
	if (err < 0) {
		printf("Unable to set buffer size %li for %s: %s\n", bufsize * 2, id, snd_strerror(err));
		return err;
	}
	if (period_size > 0)
		periodsize = period_size;
	else
		periodsize /= 2;
	err = snd_pcm_hw_params_set_period_size_near(handle, params, &periodsize, 0);
	if (err < 0) {
		printf("Unable to set period size %li for %s: %s\n", periodsize, id, snd_strerror(err));
		return err;
	}
	return 0;
}

int setparams_set(snd_pcm_t *handle,
		  snd_pcm_hw_params_t *params,
		  snd_pcm_sw_params_t *swparams,
		  const char *id)
{
	int err;
	snd_pcm_uframes_t val;

	err = snd_pcm_hw_params(handle, params);
	if (err < 0) {
		printf("Unable to set hw params for %s: %s\n", id, snd_strerror(err));
		return err;
	}
	err = snd_pcm_sw_params_current(handle, swparams);
	if (err < 0) {
		printf("Unable to determine current swparams for %s: %s\n", id, snd_strerror(err));
		return err;
	}
	err = snd_pcm_sw_params_set_start_threshold(handle, swparams, 0x7fffffff);
	if (err < 0) {
		printf("Unable to set start threshold mode for %s: %s\n", id, snd_strerror(err));
		return err;
	}
	if (!block)
		val = 4;
	else
		snd_pcm_hw_params_get_period_size(params, &val, NULL);
	err = snd_pcm_sw_params_set_avail_min(handle, swparams, val);
	if (err < 0) {
		printf("Unable to set avail min for %s: %s\n", id, snd_strerror(err));
		return err;
	}
	err = snd_pcm_sw_params(handle, swparams);
	if (err < 0) {
		printf("Unable to set sw params for %s: %s\n", id, snd_strerror(err));
		return err;
	}
	return 0;
}

int setparams(snd_pcm_t *phandle, snd_pcm_t *chandle, int *bufsize)
{
	int err, last_bufsize = *bufsize;
	snd_pcm_hw_params_t *pt_params, *ct_params;	/* templates with rate, format and channels */
	snd_pcm_hw_params_t *p_params, *c_params;
	snd_pcm_sw_params_t *p_swparams, *c_swparams;
	snd_pcm_uframes_t p_size, c_size, p_psize, c_psize;
	unsigned int p_time, c_time;
	unsigned int val;

	snd_pcm_hw_params_alloca(&p_params);
	snd_pcm_hw_params_alloca(&c_params);
	snd_pcm_hw_params_alloca(&pt_params);
	snd_pcm_hw_params_alloca(&ct_params);
	snd_pcm_sw_params_alloca(&p_swparams);
	snd_pcm_sw_params_alloca(&c_swparams);
	if ((err = setparams_stream(phandle, pt_params, "playback")) < 0) {
		printf("Unable to set parameters for playback stream: %s\n", snd_strerror(err));
		exit(0);
	}
	if ((err = setparams_stream(chandle, ct_params, "capture")) < 0) {
		printf("Unable to set parameters for playback stream: %s\n", snd_strerror(err));
		exit(0);
	}

	if (buffer_size > 0) {
		*bufsize = buffer_size;
		goto __set_it;
	}

      __again:
	printf("Trying bufsize %d\n", *bufsize);
      	if (buffer_size < 0) {
		printf("bad buffer_size?\n");
      		return -1;
	}
      	if (last_bufsize == *bufsize)
		*bufsize += 4;
	last_bufsize = *bufsize;
	if (*bufsize > latency_max) {
		printf("latency too high?\n");		
		return -1;
	}
      __set_it:
	if ((err = setparams_bufsize(phandle, p_params, pt_params, *bufsize, "playback")) < 0) {
		printf("Unable to set sw parameters for playback stream: %s\n", snd_strerror(err));
		exit(0);
	}
	if ((err = setparams_bufsize(chandle, c_params, ct_params, *bufsize, "capture")) < 0) {
		printf("Unable to set sw parameters for playback stream: %s\n", snd_strerror(err));
		exit(0);
	}

	snd_pcm_hw_params_get_period_size(p_params, &p_psize, NULL);
	if (p_psize > (unsigned int)*bufsize)
		*bufsize = p_psize;
	snd_pcm_hw_params_get_period_size(c_params, &c_psize, NULL);
	if (c_psize > (unsigned int)*bufsize)
		*bufsize = c_psize;
	snd_pcm_hw_params_get_period_time(p_params, &p_time, NULL);
	snd_pcm_hw_params_get_period_time(c_params, &c_time, NULL);
	if (p_time != c_time)
		goto __again;

	snd_pcm_hw_params_get_buffer_size(p_params, &p_size);
	if (p_psize * 2 < p_size) {
                snd_pcm_hw_params_get_periods_min(p_params, &val, NULL);
                if (val > 2) {
			printf("playback device does not support 2 periods per buffer\n");
			exit(0);
		}
		goto __again;
	}
	snd_pcm_hw_params_get_buffer_size(c_params, &c_size);
	if (c_psize * 2 < c_size) {
                snd_pcm_hw_params_get_periods_min(c_params, &val, NULL);
		if (val > 2 ) {
			printf("capture device does not support 2 periods per buffer\n");
			exit(0);
		}
		goto __again;
	}
	if ((err = setparams_set(phandle, p_params, p_swparams, "playback")) < 0) {
		printf("Unable to set sw parameters for playback stream: %s\n", snd_strerror(err));
		exit(0);
	}
	if ((err = setparams_set(chandle, c_params, c_swparams, "capture")) < 0) {
		printf("Unable to set sw parameters for playback stream: %s\n", snd_strerror(err));
		exit(0);
	}

	if ((err = snd_pcm_prepare(phandle)) < 0) {
		printf("Prepare error: %s\n", snd_strerror(err));
		exit(0);
	}

	snd_pcm_dump(phandle, output);
	snd_pcm_dump(chandle, output);
	fflush(stdout);
	return 0;
}

void showstat(snd_pcm_t *handle, size_t frames)
{
	int err;
	snd_pcm_status_t *status;

	snd_pcm_status_alloca(&status);
	if ((err = snd_pcm_status(handle, status)) < 0) {
		printf("Stream status error: %s\n", snd_strerror(err));
		exit(0);
	}
	printf("*** frames = %li ***\n", (long)frames);
	snd_pcm_status_dump(status, output);
}

void showlatency(size_t latency)
{
	double d;
	latency *= 2;
	d = (double)latency / (double)rate;
	printf("Trying latency %li frames, %.3fus, %.6fms (%.4fHz)\n", (long)latency, d * 1000000, d * 1000, (double)1 / d);
}

void showinmax(size_t in_max)
{
	double d;

	printf("Maximum read: %li frames\n", (long)in_max);
	d = (double)in_max / (double)rate;
	printf("Maximum read latency: %.3fus, %.6fms (%.4fHz)\n", d * 1000000, d * 1000, (double)1 / d);
}

void gettimestamp(snd_pcm_t *handle, snd_timestamp_t *timestamp)
{
	int err;
	snd_pcm_status_t *status;

	snd_pcm_status_alloca(&status);
	if ((err = snd_pcm_status(handle, status)) < 0) {
		printf("Stream status error: %s\n", snd_strerror(err));
		exit(0);
	}
	snd_pcm_status_get_trigger_tstamp(status, timestamp);
}

void setscheduler(void)
{
	struct sched_param sched_param;

	if (sched_getparam(0, &sched_param) < 0) {
		printf("Scheduler getparam failed...\n");
		return;
	}
	sched_param.sched_priority = sched_get_priority_max(SCHED_RR);
	if (!sched_setscheduler(0, SCHED_RR, &sched_param)) {
		printf("Scheduler set to Round Robin with priority %i...\n", sched_param.sched_priority);
		fflush(stdout);
		return;
	}
	printf("!!!Scheduler set to Round Robin with priority %i FAILED!!!\n", sched_param.sched_priority);
}

long timediff(snd_timestamp_t t1, snd_timestamp_t t2)
{
	signed long l;

	t1.tv_sec -= t2.tv_sec;
	l = (signed long) t1.tv_usec - (signed long) t2.tv_usec;
	if (l < 0) {
		t1.tv_sec--;
		l = 1000000 + l;
		l %= 1000000;
	}
	return (t1.tv_sec * 1000000) + l;
}

long readbuf(snd_pcm_t *handle, char *buf, long len, size_t *frames, size_t *max)
{
	long r;

	if (!block) {
		do {
			r = snd_pcm_readi(handle, buf, len);
		} while (r == -EAGAIN);
		if (r > 0) {
			*frames += r;
			if ((long)*max < r)
				*max = r;
		}
		// printf("read = %li\n", r);
	} else {
		int frame_bytes = (snd_pcm_format_width(format) / 8) * channels;
		do {
			r = snd_pcm_readi(handle, buf, len);
			if (r > 0) {
				buf += r * frame_bytes;
				len -= r;
				*frames += r;
				if ((long)*max < r)
					*max = r;
			}
			// printf("r = %li, len = %li\n", r, len);
		} while (r >= 1 && len > 0);
	}
	// showstat(handle, 0);
	return r;
}

long writebuf(snd_pcm_t *handle, char *buf, long len, size_t *frames)
{
	long r;

	while (len > 0) {
		r = snd_pcm_writei(handle, buf, len);
		if (r == -EAGAIN)
			continue;
		// printf("write = %li\n", r);
		if (r < 0)
			return r;
		// showstat(handle, 0);
		buf += r * 4;
		len -= r;
		*frames += r;
	}
	return 0;
}
			

int main(int argc, char *argv[])
{
	snd_pcm_t *phandle, *chandle;
	char *buffer;
	int err, latency;
	int ok;
	snd_timestamp_t p_tstamp, c_tstamp;
	ssize_t r;
	size_t frames_in, frames_out, in_max;

	err = snd_output_stdio_attach(&output, stdout, 0);
	if (err < 0) {
		printf("Output failed: %s\n", snd_strerror(err));
		return 0;
	}

	loop_limit = loop_sec * rate;
	latency = latency_min - 4;
	buffer = malloc((latency_max * snd_pcm_format_width(format) / 8) * 2);

	setscheduler();

	printf("Playback device is %s\n", pdevice);
	printf("Capture device is %s\n", cdevice);
	printf("Parameters are %iHz, %s, %i channels, %s mode\n", rate, snd_pcm_format_name(format), channels, block ? "blocking" : "non-blocking");
	printf("Poll mode: %s\n", use_poll ? "yes" : "no");
	printf("Loop limit is %li frames, minimum latency = %i, maximum latency = %i\n", loop_limit, latency_min * 2, latency_max * 2);

	if ((err = snd_pcm_open(&phandle, pdevice, SND_PCM_STREAM_PLAYBACK, block ? 0 : SND_PCM_NONBLOCK)) < 0) {
		printf("Playback open error: %s\n", snd_strerror(err));
		return 0;
	}
	if ((err = snd_pcm_open(&chandle, cdevice, SND_PCM_STREAM_CAPTURE, block ? 0 : SND_PCM_NONBLOCK)) < 0) {
		printf("Record open error: %s\n", snd_strerror(err));
		return 0;
	}

	printf("Sound ready\n");
	while (1) {
		frames_in = frames_out = 0;
		if (setparams(phandle, chandle, &latency) < 0) {
			printf("Could not set latency %d\n", latency);
			break;
		}
		showlatency(latency);
#if 1
		if ((err = snd_pcm_link(chandle, phandle)) < 0) {
			printf("Streams link error: %s\n", snd_strerror(err));
			printf("...ignoring\n");
			//exit(0);
		}
		if (snd_pcm_format_set_silence(format, buffer, latency*channels) < 0) {
			fprintf(stderr, "silence error\n");
			break;
		}
		if (writebuf(phandle, buffer, latency, &frames_out) < 0) {
			fprintf(stderr, "write error\n");
			break;
		}
		if (writebuf(phandle, buffer, latency, &frames_out) < 0) {
			fprintf(stderr, "write error\n");
			break;
		}
#endif
		printf("Sound go\n");
		if ((err = snd_pcm_start(chandle)) < 0) {
			printf("Go error: %s\n", snd_strerror(err));
			exit(0);
		}
		gettimestamp(phandle, &p_tstamp);
		gettimestamp(chandle, &c_tstamp);
#if 0
		printf("Playback:\n");
		showstat(phandle, frames_out);
		printf("Capture:\n");
		showstat(chandle, frames_in);
#endif

		ok = 1;
		in_max = 0;
		printf("Processing sound\n");
		while (ok && frames_in < loop_limit) {
			if (use_poll) {
				/* use poll to wait for next event */
				snd_pcm_wait(chandle, 1000);
			}
			if ((r = readbuf(chandle, buffer, latency, &frames_in, &in_max)) < 0)
				ok = 0;
			else {
			 	if (writebuf(phandle, buffer, r, &frames_out) < 0)
					ok = 0;
			}
		}
		if (ok)
			printf("Success\n");
		else
			printf("Failure\n");
		printf("Playback:\n");
		showstat(phandle, frames_out);
		printf("Capture:\n");
		showstat(chandle, frames_in);
		showinmax(in_max);
		if (p_tstamp.tv_sec == c_tstamp.tv_sec &&
		    p_tstamp.tv_usec == c_tstamp.tv_usec)
			printf("Hardware sync\n");
		snd_pcm_drop(chandle);
		snd_pcm_nonblock(phandle, 0);
		snd_pcm_drain(phandle);
		snd_pcm_nonblock(phandle, !block ? 1 : 0);
		if (ok) {
#if 0
			printf("Playback time = %li.%i, Record time = %li.%i, diff = %li\n",
			       p_tstamp.tv_sec,
			       (int)p_tstamp.tv_usec,
			       c_tstamp.tv_sec,
			       (int)c_tstamp.tv_usec,
			       timediff(p_tstamp, c_tstamp));
#endif
			break;
		}
		snd_pcm_unlink(chandle);
		snd_pcm_hw_free(phandle);
		snd_pcm_hw_free(chandle);
	}
	snd_pcm_close(phandle);
	snd_pcm_close(chandle);
	return 0;
}