Samples: Using Resample Port

This example demonstrates how to use Resample Port to change the sampling rate of the media streams.

This file is pjsip-apps/src/samples/resampleplay.c

/* 
 * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
 * Copyright (C) 2003-2008 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-util.h>
#include <pjlib.h>
 
#include <stdio.h>
#include <stdlib.h>
 
#include "util.h"
 
/* For logging purpose. */
#define THIS_FILE   "resampleplay.c"
 
 
static const char *desc = 
" FILE                                                              \n"
"                                                                   \n"
"  resampleplay.c                                                   \n"
"                                                                   \n"
" PURPOSE                                                           \n"
"                                                                   \n"
"  Demonstrate how use resample port to play a WAV file to sound    \n"
"  device using different sampling rate.                            \n"
"                                                                   \n"
" USAGE                                                             \n"
"                                                                   \n"
"  resampleplay [options] FILE.WAV                                  \n"
"                                                                   \n"
" where options:                                                    \n"
SND_USAGE
"                                                                   \n"
"  The WAV file could have mono or stereo channels with arbitrary   \n"
"  sampling rate, but MUST contain uncompressed (i.e. 16bit) PCM.   \n";
 
 
int main(int argc, char *argv[])
{
    pj_caching_pool cp;
    pjmedia_endpt *med_endpt;
    pj_pool_t *pool;
    pjmedia_port *file_port;
    pjmedia_port *resample_port;
    pjmedia_snd_port *snd_port;
    char tmp[10];
    pj_status_t status;
 
    int dev_id = -1;
    int sampling_rate = CLOCK_RATE;
    int channel_count = NCHANNELS;
    int samples_per_frame = NSAMPLES;
    int bits_per_sample = NBITS;
    //int ptime;
    //int down_samples;
 
    /* Must init PJLIB first: */
    status = pj_init();
    PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
 
 
    /* Get options */
    if (get_snd_options(THIS_FILE, argc, argv, &dev_id, &sampling_rate,
                        &channel_count, &samples_per_frame, &bits_per_sample))
    {
        puts("");
        puts(desc);
        return 1;
    }
 
    if (!argv[pj_optind]) {
        puts("Error: no file is specified");
        puts(desc);
        return 1;
    }
 
    /* Must create a pool factory before we can allocate any memory. */
    pj_caching_pool_init(&cp, &pj_pool_factory_default_policy, 0);
 
    /* 
     * Initialize media endpoint.
     * This will implicitly initialize PJMEDIA too.
     */
    status = pjmedia_endpt_create(&cp.factory, NULL, 1, &med_endpt);
    PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
 
    /* Create memory pool for our file player */
    pool = pj_pool_create( &cp.factory,     /* pool factory         */
                           "app",           /* pool name.           */
                           4000,            /* init size            */
                           4000,            /* increment size       */
                           NULL             /* callback on error    */
                           );
 
    /* Create the file port. */
    status = pjmedia_wav_player_port_create( pool, argv[pj_optind], 0, 0,
                                             0, &file_port);
    if (status != PJ_SUCCESS) {
        app_perror(THIS_FILE, "Unable to open file", status);
        return 1;
    }
 
    /* File must have same number of channels. */
    if (PJMEDIA_PIA_CCNT(&file_port->info) != (unsigned)channel_count) {
        PJ_LOG(3,(THIS_FILE, "Error: file has different number of channels. "
                             "Perhaps you'd need -c option?"));
        pjmedia_port_destroy(file_port);
        return 1;
    }
 
    /* Calculate number of samples per frame to be taken from file port */
    //ptime = samples_per_frame * 1000 / sampling_rate;
 
    /* Create the resample port. */
    status = pjmedia_resample_port_create( pool, file_port,
                                           sampling_rate, 0,
                                           &resample_port);
    if (status != PJ_SUCCESS) {
        app_perror(THIS_FILE, "Unable to create resample port", status);
        return 1;
    }
 
    /* Create sound player port. */
    status = pjmedia_snd_port_create( 
                 pool,                  /* pool                     */
                 dev_id,                /* device                   */
                 dev_id,                /* device                   */
                 sampling_rate,         /* clock rate.              */
                 channel_count,         /* # of channels.           */
                 samples_per_frame,     /* samples per frame.       */
                 bits_per_sample,       /* bits per sample.         */
                 0,                     /* options                  */
                 &snd_port              /* returned port            */
                 );
    if (status != PJ_SUCCESS) {
        app_perror(THIS_FILE, "Unable to open sound device", status);
        return 1;
    }
 
    /* Connect resample port to sound device */
    status = pjmedia_snd_port_connect( snd_port, resample_port);
    if (status != PJ_SUCCESS) {
        app_perror(THIS_FILE, "Error connecting sound ports", status);
        return 1;
    }
 
 
    /* Dump memory usage */
    dump_pool_usage(THIS_FILE, &cp);
 
    /* 
     * File should be playing and looping now, using sound device's thread. 
     */
 
 
    /* Sleep to allow log messages to flush */
    pj_thread_sleep(100);
 
 
    printf("Playing %s at sampling rate %d (original file sampling rate=%d)\n",
           argv[pj_optind], sampling_rate,
           PJMEDIA_PIA_SRATE(&file_port->info));
    puts("");
    puts("Press <ENTER> to stop playing and quit");
 
    if (fgets(tmp, sizeof(tmp), stdin) == NULL) {
        puts("EOF while reading stdin, will quit now..");
    }
    
    /* Start deinitialization: */
 
 
    /* Destroy sound device */
    status = pjmedia_snd_port_destroy( snd_port );
    PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
 
 
    /* Destroy resample port. 
     * This will destroy all downstream ports (e.g. the file port)
     */
    status = pjmedia_port_destroy( resample_port );
    PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
 
 
    /* Release application pool */
    pj_pool_release( pool );
 
    /* Destroy media endpoint. */
    pjmedia_endpt_destroy( med_endpt );
 
    /* Destroy pool factory */
    pj_caching_pool_destroy( &cp );
 
    /* Shutdown PJLIB */
    pj_shutdown();
 
 
    /* Done. */
    return 0;
 
}