MeasuringSoundLatency: latency.c

/* $Id:$ */
/* 
 * Copyright (C) 2003-2007 Benny Prijono <benny@prijono.org>
 *
 * 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 <pjmedia.h>
#include <pjlib.h>

#include <stdio.h>

#define THIS_FILE   "lacency.c"


/* Util to display the error message for the specified error code  */
static int app_perror( const char *sender, const char *title, 
                       pj_status_t status)
{
    char errmsg[PJ_ERR_MSG_SIZE];

    PJ_UNUSED_ARG(sender);

    pj_strerror(status, errmsg, sizeof(errmsg));

    printf("%s: %s [code=%d]\n", title, errmsg, status);
    return 1;
}

/*
 * Find out latency
 */
static int calculate_latency(pj_pool_t *pool, pjmedia_port *wav)
{
    pjmedia_frame frm;
    short *buf;
    unsigned i, samples_per_frame, read, len;
    unsigned start_pos;
    pj_status_t status;

    unsigned lat_sum = 0,
             lat_cnt = 0,
             lat_min = 10000,
             lat_max = 0;

    samples_per_frame = wav->info.samples_per_frame;
    frm.buf = pj_pool_alloc(pool, samples_per_frame * 2);
    frm.size = samples_per_frame * 2;
    len = pjmedia_wav_player_get_len(wav);
    buf = pj_pool_alloc(pool, len + samples_per_frame);

    read = 0;
    while (read < len/2) {
        status = pjmedia_port_get_frame(wav, &frm);
        if (status != PJ_SUCCESS)
            break;

        pjmedia_copy_samples(buf+read, (short*)frm.buf, samples_per_frame);
        read += samples_per_frame;
    }

    if (read < 2 * wav->info.clock_rate) {
        puts("Error: too short");
        return -1;
    }

    start_pos = 0;
    while (start_pos < len/2 - wav->info.clock_rate) {
        int max_signal = 0;
        unsigned max_signal_pos = start_pos;
        unsigned max_echo_pos = 0;
        unsigned pos;
        unsigned lat;

        /* Get the largest signal in the next 0.7s */
        for (i=start_pos; i<start_pos + wav->info.clock_rate * 700 / 1000; ++i) {
            if (abs(buf[i]) > max_signal) {
                max_signal = abs(buf[i]);
                max_signal_pos = i;
            }
        }

        /* Advance 10ms from max_signal_pos */
        pos = max_signal_pos + 10 * wav->info.clock_rate / 1000;

        /* Get the largest signal in the next 500ms */
        max_signal = 0;
        max_echo_pos = pos;
        for (i=pos; i<pos+wav->info.clock_rate/2; ++i) {
            if (abs(buf[i]) > max_signal) {
                max_signal = abs(buf[i]);
                max_echo_pos = i;
            }
        }

        lat = (max_echo_pos - max_signal_pos) * 1000 / wav->info.clock_rate;
        
#if 0
        printf("Latency = %u\n", lat);
#endif

        lat_sum += lat;
        lat_cnt++;
        if (lat < lat_min)
            lat_min = lat;
        if (lat > lat_max)
            lat_max = lat;

        /* Advance next loop */
        start_pos += wav->info.clock_rate;
    }

    printf("Latency average = %u\n", lat_sum / lat_cnt);
    printf("Latency minimum = %u\n", lat_min);
    printf("Latency maximum = %u\n", lat_max);
    printf("Number of data  = %u\n", lat_cnt);
    return 0;
}

/*
To calculate sound latency:
pjsua_vc6 --ec-tail 0 --rec-file rec.wav --play-file tock.wav

cc 0 0
cc 1 0
cc 1 2
cc 0 2
sleep 30000
cd 0 0
cd 1 0
cd 1 2
cd 0 2
q


To calculate network latency:
pjsua_vc6 --ec-tail 0 --rec-file rec.wav --play-file tock.wav --null-audio

m
sip:192.168.0.2:5090
sleep 200
cd 0 4
cd 4 0
cc 1 2
cc 4 2
cc 1 4
sleep 30000
cd 1 2
cd 4 2
cd 1 4
h
sleep 500
q


 */

/*
 * main()
 */
int main(int argc, char *argv[])
{
    enum { NSAMPLES = 160, COUNT=100 };
    pj_caching_pool cp;
    pj_pool_t *pool;
    pjmedia_port *wav;
    pj_status_t status;


    /* Verify cmd line arguments. */
    if (argc != 2) {
        puts("Error: missing argument(s)");
        puts("Usage: latency REV.WAV");
        return 1;
    }

    pj_log_set_level(0);

    status = pj_init();
    PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);

    pj_caching_pool_init(&cp, &pj_pool_factory_default_policy, 0);

    pool = pj_pool_create( &cp.factory,     /* pool factory         */
                           "wav",           /* pool name.           */
                           4000,            /* init size            */
                           4000,            /* increment size       */
                           NULL             /* callback on error    */
                           );

    pj_register_strerror(PJMEDIA_ERRNO_START, PJ_ERRNO_SPACE_SIZE, 
                         &pjmedia_strerror);

    /* Wav */
    status = pjmedia_wav_player_port_create(  pool,     /* memory pool      */
                                              argv[1],  /* file to play     */
                                              0,        /* use default ptime*/
                                              0,        /* flags            */
                                              0,        /* default buffer   */
                                              &wav      /* returned port    */
                                              );
    if (status != PJ_SUCCESS) {
        app_perror(THIS_FILE, argv[1], status);
        return 1;
    }

    status = calculate_latency(pool, wav);
    if (status != PJ_SUCCESS)
        return 1;

    status = pjmedia_port_destroy( wav );
    PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);

    pj_pool_release( pool );
    pj_caching_pool_destroy( &cp );
    pj_shutdown();

    /* Done. */
    return 0;
}