ALSA project - the C library reference: /test/latency.c

# /test/latency.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 "../include/asoundlib.h"
    #include <sys/time.h>
    #include <math.h>

    char *pdevice = "hw:0,0";
    char *cdevice = "hw:0,0";
    snd_pcm_format_t format = SND_PCM_FORMAT_S16_LE;
    int rate = 22050;
    int channels = 2;
    int buffer_size = 0;            /* auto */
    int period_size = 0;            /* auto */
    int latency_min = 32;           /* in frames / 2 */
    int latency_max = 2048;         /* in frames / 2 */
    int loop_sec = 30;              /* 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:
            if (buffer_size > 0)
                    return -1;
            if (last_bufsize == *bufsize)
                    *bufsize += 4;
            last_bufsize = *bufsize;
            if (*bufsize > latency_max)
                    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;
    }

    #define FILTERSWEEP_LFO_CENTER 2000.
    #define FILTERSWEEP_LFO_DEPTH 1800.
    #define FILTERSWEEP_LFO_FREQ 0.2
    #define FILTER_BANDWIDTH 50

    /* filter the sweep variables */
    float lfo,dlfo,fs,fc,BW,C,D,a0,a1,a2,b1,b2,*x[3],*y[3];

    void applyeffect(char* buffer,int r)
    {
            short* samples = (short*) buffer;
            int i;
            for (i=0;i<r;i++)
            {
                    int chn;

                    fc = sin(lfo)*FILTERSWEEP_LFO_DEPTH+FILTERSWEEP_LFO_CENTER;
                    lfo += dlfo;
                    if (lfo>2.*M_PI) lfo -= 2.*M_PI;
                    C = 1./tan(M_PI*BW/fs);
                    D = 2.*cos(2*M_PI*fc/fs);
                    a0 = 1./(1.+C);
                    a1 = 0;
                    a2 = -a0;
                    b1 = -C*D*a0;
                    b2 = (C-1)*a0;

                    for (chn=0;chn<channels;chn++)
                    {
                            x[chn][2] = x[chn][1];
                            x[chn][1] = x[chn][0];

                            y[chn][2] = y[chn][1];
                            y[chn][1] = y[chn][0];

                            x[chn][0] = samples[i*channels+chn];
                            y[chn][0] = a0*x[chn][0] + a1*x[chn][1] + a2*x[chn][2]
                                    - b1*y[chn][1] - b2*y[chn][2];
                            samples[i*channels+chn] = y[chn][0];
                    }
            }
    }

    void help(void)
    {
            int k;
            printf(
    "Usage: latency [OPTION]... [FILE]...\n"
    "-h,--help      help\n"
    "-P,--pdevice   playback device\n"
    "-C,--cdevice   capture device\n"
    "-m,--min       minimum latency in frames\n"
    "-M,--max       maximum latency in frames\n"
    "-F,--frames    frames to transfer\n"
    "-f,--format    sample format\n"
    "-c,--channels  channels\n"
    "-r,--rate      rate\n"
    "-B,--buffer    buffer size in frames\n"
    "-E,--period    period size in frames\n"
    "-s,--seconds   duration of test in seconds\n"
    "-b,--block     block mode\n"
    "-p,--poll      use poll (wait for event - reduces CPU usage)\n"
    "-e,--effect    apply an effect (bandpass filter sweep)\n"
    );
            printf("Recognized sample formats are:");
            for (k = 0; k < SND_PCM_FORMAT_LAST; ++k) {
                    const char *s = snd_pcm_format_name(k);
                    if (s)
                            printf(" %s", s);
            }
            printf("\n\n");
            printf(
    "Tip #1 (usable latency with large periods, non-blocking mode, good CPU usage,\n"
    "        superb xrun prevention):\n"
    "  latency -m 8192 -M 8192 -t 1 -p\n"
    "Tip #2 (superb latency, non-blocking mode, but heavy CPU usage):\n"
    "  latency -m 128 -M 128\n"
    );
    }

    int main(int argc, char *argv[])
    {
            struct option long_option[] =
            {
                    {"help", 0, NULL, 'h'},
                    {"pdevice", 1, NULL, 'P'},
                    {"cdevice", 1, NULL, 'C'},
                    {"min", 1, NULL, 'm'},
                    {"max", 1, NULL, 'M'},
                    {"frames", 1, NULL, 'F'},
                    {"format", 1, NULL, 'f'},
                    {"channels", 1, NULL, 'c'},
                    {"rate", 1, NULL, 'r'},
                    {"buffer", 1, NULL, 'B'},
                    {"period", 1, NULL, 'E'},
                    {"seconds", 1, NULL, 's'},
                    {"block", 0, NULL, 'b'},
                    {"poll", 0, NULL, 'p'},
                    {"effect", 0, NULL, 'e'},
                    {NULL, 0, NULL, 0},
            };
            snd_pcm_t *phandle, *chandle;
            char *buffer;
            int err, latency, morehelp;
            int ok;
            snd_timestamp_t p_tstamp, c_tstamp;
            ssize_t r;
            size_t frames_in, frames_out, in_max;
            int effect = 0;
            morehelp = 0;
            while (1) {
                    int c;
                    if ((c = getopt_long(argc, argv, "hP:C:m:M:F:f:c:r:B:E:s:bpen", long_option, NULL)) < 0)
                            break;
                    switch (c) {
                    case 'h':
                            morehelp++;
                            break;
                    case 'P':
                            pdevice = strdup(optarg);
                            break;
                    case 'C':
                            cdevice = strdup(optarg);
                            break;
                    case 'm':
                            err = atoi(optarg) / 2;
                            latency_min = err >= 4 ? err : 4;
                            if (latency_max < latency_min)
                                    latency_max = latency_min;
                            break;
                    case 'M':
                            err = atoi(optarg) / 2;
                            latency_max = latency_min > err ? latency_min : err;
                            break;
                    case 'f':
                            format = snd_pcm_format_value(optarg);
                            if (format == SND_PCM_FORMAT_UNKNOWN) {
                                    printf("Unknown format, setting to default S16_LE\n");
                                    format = SND_PCM_FORMAT_S16_LE;
                            }
                            break;
                    case 'c':
                            err = atoi(optarg);
                            channels = err >= 1 && err < 1024 ? err : 1;
                            break;
                    case 'r':
                            err = atoi(optarg);
                            rate = err >= 4000 && err < 200000 ? err : 44100;
                            break;
                    case 'B':
                            err = atoi(optarg);
                            buffer_size = err >= 32 && err < 200000 ? err : 0;
                            break;
                    case 'E':
                            err = atoi(optarg);
                            period_size = err >= 32 && err < 200000 ? err : 0;
                            break;
                    case 's':
                            err = atoi(optarg);
                            loop_sec = err >= 1 && err <= 100000 ? err : 30;
                            break;
                    case 'b':
                            block = 1;
                            break;
                    case 'p':
                            use_poll = 1;
                            break;
                    case 'e':
                            effect = 1;
                            break;
                    case 'n':
                            resample = 0;
                            break;
                    }
            }

            if (morehelp) {
                    help();
                    return 0;
            }
            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;
            }

            /* initialize the filter sweep variables */
            if (effect) {
                    fs = (float) rate;
                    BW = FILTER_BANDWIDTH;

                    lfo = 0;
                    dlfo = 2.*M_PI*FILTERSWEEP_LFO_FREQ/fs;

                    x[0] = (float*) malloc(channels*sizeof(float));
                    x[1] = (float*) malloc(channels*sizeof(float));
                    x[2] = (float*) malloc(channels*sizeof(float));
                    y[0] = (float*) malloc(channels*sizeof(float));
                    y[1] = (float*) malloc(channels*sizeof(float));
                    y[2] = (float*) malloc(channels*sizeof(float));
            }

            while (1) {
                    frames_in = frames_out = 0;
                    if (setparams(phandle, chandle, &latency) < 0)
                            break;
                    showlatency(latency);
                    if ((err = snd_pcm_link(chandle, phandle)) < 0) {
                            printf("Streams link error: %s\n", snd_strerror(err));
                            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;
                    }

                    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;
                    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 (effect)
                                            applyeffect(buffer,r);
                                    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 == p_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 1
                            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;
    }

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