patest_sync.c

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/*
 * $Id: patest_sync.c,v 1.2 2003/03/02 08:01:43 dmazzoni Exp $
 * patest_sync.c
 * Test time stamping and synchronization of audio and video.
 * A high latency is used so we can hear the difference in time.
 * Random durations are used so we know we are hearing the right beep
 * and not the one before or after.
 *
 * Sequence of events:
 *    Foreground requests a beep.
 *    Background randomly schedules a beep.
 *    Foreground waits for the beep to be heard based on Pa_StreamTime().
 *    Foreground outputs video (printf) in sync with audio.
 *    Repeat.
 *
 * Author: Phil Burk  http://www.softsynth.com
 *
 * This program uses the PortAudio Portable Audio Library.
 * For more information see: http://www.portaudio.com
 * Copyright (c) 1999-2000 Ross Bencina and Phil Burk
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * Any person wishing to distribute modifications to the Software is
 * requested to send the modifications to the original developer so that
 * they can be incorporated into the canonical version.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 */
#include <stdio.h>
#include <math.h>
#include "portaudio.h"
#define NUM_BEEPS           (6)
#define SAMPLE_RATE         (44100)
#define FRAMES_PER_BUFFER   (256)
#define BEEP_DURATION       (1000)
#define LATENCY_MSEC        (2000)
#define SLEEP_MSEC          (10)
#define TIMEOUT_MSEC        ((3 * LATENCY_MSEC) / (2 * SLEEP_MSEC))
#define NUM_BUFFERS         ((LATENCY_MSEC * SAMPLE_RATE) / (FRAMES_PER_BUFFER * 1000))
#define STATE_BKG_IDLE    (0)
#define STATE_BKG_PENDING (1)
#define STATE_BKG_BEEPING (2)
typedef struct
{
    float        left_phase;
    float        right_phase;
    int          state;
    int          requestBeep;  /* Set by foreground, cleared by background. */
    PaTimestamp  beepTime;
    int          beepCount;
}
paTestData;
static unsigned long GenerateRandomNumber( void );
/************************************************************/
/* Calculate pseudo-random 32 bit number based on linear congruential method. */
static unsigned long GenerateRandomNumber( void )
{
    static unsigned long randSeed = 22222;  /* Change this for different random sequences. */
    randSeed = (randSeed * 196314165) + 907633515;
    return randSeed;
}
/* This routine will be called by the PortAudio engine when audio is needed.
** It may called at interrupt level on some machines so don't do anything
** that could mess up the system like calling malloc() or free().
*/
static int patestCallback( void *inputBuffer, void *outputBuffer,
                           unsigned long framesPerBuffer,
                           PaTimestamp outTime, void *userData )
{
    /* Cast data passed through stream to our structure. */
    paTestData *data = (paTestData*)userData;
    float *out = (float*)outputBuffer;
    unsigned int i;
    (void) inputBuffer;

    for( i=0; i<framesPerBuffer; i++ )
    {
        switch( data->state )
        {
        case STATE_BKG_IDLE:
            /* Schedule beep at some random time in the future. */
            if( data->requestBeep )
            {
                int random = GenerateRandomNumber() >> 14;
                data->beepTime = outTime + (i + random + (SAMPLE_RATE/4));
                data->state = STATE_BKG_PENDING;
                data->requestBeep = 0;
                data->left_phase = data->right_phase = 0.0;
            }
            *out++ = 0.0;  /* left */
            *out++ = 0.0;  /* right */
            break;
        case STATE_BKG_PENDING:
            if( (outTime + i) >= data->beepTime )
            {
                data->state = STATE_BKG_BEEPING;
                data->beepCount = BEEP_DURATION;
            }
            *out++ = 0.0;  /* left */
            *out++ = 0.0;  /* right */
            break;
        case STATE_BKG_BEEPING:
            if( data->beepCount <= 0 )
            {
                data->state = STATE_BKG_IDLE;
                *out++ = 0.0;  /* left */
                *out++ = 0.0;  /* right */
            }
            else
            {
                /* Play sawtooth wave. */
                *out++ = data->left_phase;  /* left */
                *out++ = data->right_phase;  /* right */
                /* Generate simple sawtooth phaser that ranges between -1.0 and 1.0. */
                data->left_phase += 0.01f;
                /* When signal reaches top, drop back down. */
                if( data->left_phase >= 1.0f ) data->left_phase -= 2.0f;
                /* higher pitch so we can distinguish left and right. */
                data->right_phase += 0.03f;
                if( data->right_phase >= 1.0f ) data->right_phase -= 2.0f;
            }
            data->beepCount -= 1;
            break;
        default:
            data->state = STATE_BKG_IDLE;
            break;
        }
    }
    return 0;
}
/*******************************************************************/
int main(void);
int main(void)
{
    PortAudioStream *stream;
    PaError    err;
    paTestData DATA;
    int        i, timeout;
    PaTimestamp  previousTime;
    printf("PortAudio Test: you should see BEEP at the same time you hear it.\n");
    printf("Wait for a few seconds random delay between BEEPs.\n");
    printf("BEEP %d times.\n", NUM_BEEPS );
    /* Initialize our DATA for use by callback. */
    DATA.left_phase = DATA.right_phase = 0.0;
    DATA.state = STATE_BKG_IDLE;
    DATA.requestBeep = 0;
    /* Initialize library before making any other calls. */
    err = Pa_Initialize();
    if( err != paNoError ) goto error;
    /* Open an audio I/O stream. */
    err = Pa_OpenDefaultStream(
              &stream,
              0,              /* no input channels */
              2,              /* stereo output */
              paFloat32,      /* 32 bit floating point output */
              SAMPLE_RATE,
              FRAMES_PER_BUFFER,
              NUM_BUFFERS,
              patestCallback,
              &DATA );
    if( err != paNoError ) goto error;
    err = Pa_StartStream( stream );
    if( err != paNoError ) goto error;
    previousTime = Pa_StreamTime( stream );
    for( i=0; i<NUM_BEEPS; i++ )
    {
        /* Request a beep from background. */
        DATA.requestBeep = 1;
        /* Wait for background to acknowledge request. */
        timeout = TIMEOUT_MSEC;
        while( (DATA.requestBeep == 1) && (timeout-- > 0 ) ) Pa_Sleep(SLEEP_MSEC);
        if( timeout <= 0 )
        {
            fprintf( stderr, "Timed out waiting for background to acknowledge request.\n" );
            goto error;
        }
        /* Wait for scheduled beep time. */
        timeout =  TIMEOUT_MSEC + (10000/SLEEP_MSEC);
        while( (Pa_StreamTime( stream ) < DATA.beepTime) && (timeout-- > 0 ) )
        {
            Pa_Sleep(SLEEP_MSEC);
        }
        if( timeout <= 0 )
        {
            fprintf( stderr, "Timed out waiting for time. Now = %g, Beep for %g.\n",
                     Pa_StreamTime( stream ), DATA.beepTime );
            goto error;
        }
        /* Beep should be sounding now so print synchronized BEEP. */
        printf("BEEP");
        fflush(stdout);
        printf(" at %d, delta = %d\n",
               (long) DATA.beepTime, (long) (DATA.beepTime - previousTime) );
        fflush(stdout);
        previousTime = DATA.beepTime;
    }
    err = Pa_StopStream( stream );
    if( err != paNoError ) goto error;
    err = Pa_CloseStream( stream );
    if( err != paNoError ) goto error;
    Pa_Terminate();
    printf("Test finished.\n");
    return err;
error:
    Pa_Terminate();
    fprintf( stderr, "An error occured while using the portaudio stream\n" );
    fprintf( stderr, "Error number: %d\n", err );
    fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
    return err;
}