134 lines
4.8 KiB
C
134 lines
4.8 KiB
C
/** @file paex_saw.c
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@ingroup examples_src
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@brief Play a simple (aliasing) sawtooth wave.
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@author Phil Burk http://www.softsynth.com
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*/
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/*
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* $Id$
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*
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* This program uses the PortAudio Portable Audio Library.
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* For more information see: http://www.portaudio.com
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* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files
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* (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
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* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
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* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/*
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* The text above constitutes the entire PortAudio license; however,
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* the PortAudio community also makes the following non-binding requests:
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*
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* Any person wishing to distribute modifications to the Software is
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* requested to send the modifications to the original developer so that
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* they can be incorporated into the canonical version. It is also
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* requested that these non-binding requests be included along with the
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* license above.
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*/
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#include <stdio.h>
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#include <math.h>
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#include "portaudio.h"
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#define NUM_SECONDS (4)
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#define SAMPLE_RATE (44100)
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typedef struct
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{
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float left_phase;
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float right_phase;
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}
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paTestData;
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/* This routine will be called by the PortAudio engine when audio is needed.
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** It may called at interrupt level on some machines so don't do anything
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** that could mess up the system like calling malloc() or free().
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*/
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static int patestCallback( const void *inputBuffer, void *outputBuffer,
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unsigned long framesPerBuffer,
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const PaStreamCallbackTimeInfo* timeInfo,
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PaStreamCallbackFlags statusFlags,
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void *userData )
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{
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/* Cast data passed through stream to our structure. */
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paTestData *data = (paTestData*)userData;
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float *out = (float*)outputBuffer;
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unsigned int i;
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(void) inputBuffer; /* Prevent unused variable warning. */
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for( i=0; i<framesPerBuffer; i++ )
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{
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*out++ = data->left_phase; /* left */
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*out++ = data->right_phase; /* right */
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/* Generate simple sawtooth phaser that ranges between -1.0 and 1.0. */
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data->left_phase += 0.01f;
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/* When signal reaches top, drop back down. */
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if( data->left_phase >= 1.0f ) data->left_phase -= 2.0f;
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/* higher pitch so we can distinguish left and right. */
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data->right_phase += 0.03f;
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if( data->right_phase >= 1.0f ) data->right_phase -= 2.0f;
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}
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return 0;
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}
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/*******************************************************************/
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static paTestData data;
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int main(void);
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int main(void)
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{
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PaStream *stream;
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PaError err;
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printf("PortAudio Test: output sawtooth wave.\n");
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/* Initialize our data for use by callback. */
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data.left_phase = data.right_phase = 0.0;
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/* Initialize library before making any other calls. */
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err = Pa_Initialize();
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if( err != paNoError ) goto error;
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/* Open an audio I/O stream. */
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err = Pa_OpenDefaultStream( &stream,
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0, /* no input channels */
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2, /* stereo output */
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paFloat32, /* 32 bit floating point output */
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SAMPLE_RATE,
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256, /* frames per buffer */
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patestCallback,
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&data );
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if( err != paNoError ) goto error;
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err = Pa_StartStream( stream );
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if( err != paNoError ) goto error;
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/* Sleep for several seconds. */
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Pa_Sleep(NUM_SECONDS*1000);
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err = Pa_StopStream( stream );
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if( err != paNoError ) goto error;
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err = Pa_CloseStream( stream );
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if( err != paNoError ) goto error;
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Pa_Terminate();
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printf("Test finished.\n");
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return err;
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error:
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Pa_Terminate();
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fprintf( stderr, "An error occurred while using the portaudio stream\n" );
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fprintf( stderr, "Error number: %d\n", err );
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fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
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return err;
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}
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