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/* $Id: playsine.c 3664 2011-07-19 03:42:28Z nanang $ */
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* Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
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* Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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* \page page_pjmedia_samples_playsine_c Samples: Using Custom Ports (Sine Wave Generator)
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* This example demonstrate how to create a custom media port (in this case, a
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* sine wave generator) and connect it to the sound device.
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* This file is pjsip-apps/src/samples/playsine.c
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* \includelineno playsine.c
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* Demonstrate how to create and use custom media port which
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* simply feed a sine wav to the sound player.
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* nchannel is 1 for mono (this is the default) or 2 for stereo.
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#include <stdlib.h> /* atoi() */
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#include <math.h> /* sin() */
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/* For logging purpose. */
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#define THIS_FILE "playsine.c"
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/* Util to display the error message for the specified error code */
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static int app_perror( const char *sender, const char *title,
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char errmsg[PJ_ERR_MSG_SIZE];
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PJ_UNUSED_ARG(sender);
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pj_strerror(status, errmsg, sizeof(errmsg));
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printf("%s: %s [code=%d]\n", title, errmsg, status);
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/* Struct attached to sine generator */
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pj_int16_t *samples; /* Sine samples. */
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/* This callback is called to feed more samples */
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static pj_status_t sine_get_frame( pjmedia_port *port,
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port_data *sine = port->port_data.pdata;
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pj_int16_t *samples = frame->buf;
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unsigned i, count, left, right;
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/* Get number of samples */
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count = frame->size / 2 / PJMEDIA_PIA_CCNT(&port->info);
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for (i=0; i<count; ++i) {
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*samples++ = sine->samples[left];
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if (PJMEDIA_PIA_CCNT(&port->info) == 2) {
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*samples++ = sine->samples[right];
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right += 2; /* higher pitch so we can distinguish left and right. */
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/* Must set frame->type correctly, otherwise the sound device
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* will refuse to play.
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frame->type = PJMEDIA_FRAME_TYPE_AUDIO;
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#define M_PI (3.14159265)
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* Create a media port to generate sine wave samples.
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static pj_status_t create_sine_port(pj_pool_t *pool,
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unsigned sampling_rate,
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unsigned channel_count,
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pjmedia_port **p_port)
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PJ_ASSERT_RETURN(pool && channel_count > 0 && channel_count <= 2,
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port = pj_pool_zalloc(pool, sizeof(pjmedia_port));
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PJ_ASSERT_RETURN(port != NULL, PJ_ENOMEM);
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/* Fill in port info. */
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name = pj_str("sine generator");
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pjmedia_port_info_init(&port->info, &name,
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PJMEDIA_SIG_CLASS_PORT_AUD('s', 'i'),
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16, sampling_rate * 20 / 1000 * channel_count);
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/* Set the function to feed frame */
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port->get_frame = &sine_get_frame;
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/* Create sine port data */
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port->port_data.pdata = sine = pj_pool_zalloc(pool, sizeof(port_data));
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count = PJMEDIA_PIA_SPF(&port->info) / channel_count;
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sine->samples = pj_pool_alloc(pool, count * sizeof(pj_int16_t));
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PJ_ASSERT_RETURN(sine->samples != NULL, PJ_ENOMEM);
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/* initialise sinusoidal wavetable */
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for( i=0; i<count; i++ )
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sine->samples[i] = (pj_int16_t) (10000.0 *
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sin(((double)i/(double)count) * M_PI * 8.) );
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static void usage(void)
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puts("Usage: playsine [nchannel]");
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puts(" nchannel is number of audio channels (1 for mono, or 2 for stereo).");
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puts(" Default is 1 (mono).");
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int main(int argc, char *argv[])
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pjmedia_endpt *med_endpt;
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pjmedia_port *sine_port;
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pjmedia_snd_port *snd_port;
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int channel_count = 1;
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channel_count = atoi(argv[1]);
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if (channel_count < 1 || channel_count > 2) {
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puts("Error: invalid arguments");
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/* Must init PJLIB first: */
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PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
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/* Must create a pool factory before we can allocate any memory. */
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pj_caching_pool_init(&cp, &pj_pool_factory_default_policy, 0);
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* Initialize media endpoint.
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* This will implicitly initialize PJMEDIA too.
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status = pjmedia_endpt_create(&cp.factory, NULL, 1, &med_endpt);
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PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
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/* Create memory pool for our sine generator */
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pool = pj_pool_create( &cp.factory, /* pool factory */
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"wav", /* pool name. */
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4000, /* init size */
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4000, /* increment size */
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NULL /* callback on error */
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/* Create a media port to generate sine wave samples. */
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status = create_sine_port( pool, /* memory pool */
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11025, /* sampling rate */
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channel_count,/* # of channels */
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&sine_port /* returned port */
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if (status != PJ_SUCCESS) {
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app_perror(THIS_FILE, "Unable to create sine port", status);
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/* Create sound player port. */
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status = pjmedia_snd_port_create_player(
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-1, /* use default dev. */
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PJMEDIA_PIA_SRATE(&sine_port->info),/* clock rate. */
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PJMEDIA_PIA_CCNT(&sine_port->info),/* # of channels. */
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PJMEDIA_PIA_SPF(&sine_port->info), /* samples per frame. */
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PJMEDIA_PIA_BITS(&sine_port->info),/* bits per sample. */
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&snd_port /* returned port */
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if (status != PJ_SUCCESS) {
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app_perror(THIS_FILE, "Unable to open sound device", status);
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/* Connect sine generator port to the sound player
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* Stream playing will commence immediately.
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status = pjmedia_snd_port_connect( snd_port, sine_port);
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PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
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* Audio should be playing in a loop now, using sound device's thread.
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/* Sleep to allow log messages to flush */
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pj_thread_sleep(100);
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puts("Playing sine wave..");
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puts("Press <ENTER> to stop playing and quit");
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if (fgets(tmp, sizeof(tmp), stdin) == NULL) {
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puts("EOF while reading stdin, will quit now..");
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/* Start deinitialization: */
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/* Disconnect sound port from file port */
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status = pjmedia_snd_port_disconnect(snd_port);
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PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
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/* Without this sleep, Windows/DirectSound will repeteadly
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* play the last frame during destroy.
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pj_thread_sleep(100);
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/* Destroy sound device */
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status = pjmedia_snd_port_destroy( snd_port );
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PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
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/* Destroy sine generator */
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status = pjmedia_port_destroy( sine_port );
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PJ_ASSERT_RETURN(status == PJ_SUCCESS, 1);
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/* Release application pool */
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pj_pool_release( pool );
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/* Destroy media endpoint. */
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pjmedia_endpt_destroy( med_endpt );
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/* Destroy pool factory */
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pj_caching_pool_destroy( &cp );