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/** @file patest_dither.c
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@brief Attempt to hear difference between dithered and non-dithered signal.
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This only has an effect if the native format is 16 bit.
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@author Phil Burk http://www.softsynth.com
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* $Id: patest_dither.c,v 1.2 2006/09/23 18:42:51 llucius Exp $
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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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* 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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* 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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* 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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* 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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* 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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#include "portaudio.h"
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#define NUM_SECONDS (5)
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#define SAMPLE_RATE (44100)
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#define M_PI (3.14159265)
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#define TABLE_SIZE (200)
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typedef struct paTestData
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float sine[TABLE_SIZE];
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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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static int sineCallback( 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, void *userData )
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paTestData *data = (paTestData*)userData;
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float *out = (float*)outputBuffer;
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float amplitude = data->amplitude;
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for( i=0; i<framesPerBuffer; i++ )
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*out++ = amplitude * data->sine[data->left_phase]; /* left */
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*out++ = amplitude * data->sine[data->right_phase]; /* right */
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data->left_phase += 1;
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if( data->left_phase >= TABLE_SIZE ) data->left_phase -= TABLE_SIZE;
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data->right_phase += 3; /* higher pitch so we can distinguish left and right. */
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if( data->right_phase >= TABLE_SIZE ) data->right_phase -= TABLE_SIZE;
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/*****************************************************************************/
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V18 version did not call Pa_Terminate() if Pa_Initialize() failed.
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This V19 version ALWAYS calls Pa_Terminate(). PS.
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PaError PlaySine( paTestData *data, PaStreamFlags flags, float amplitude );
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PaError PlaySine( paTestData *data, PaStreamFlags flags, float amplitude )
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PaStreamParameters outputParameters;
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data->left_phase = data->right_phase = 0;
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data->amplitude = amplitude;
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err = Pa_Initialize();
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if (err != paNoError)
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outputParameters.device = Pa_GetDefaultOutputDevice(); /* default output device */
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outputParameters.channelCount = 2; /* stereo output */
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outputParameters.hostApiSpecificStreamInfo = NULL;
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outputParameters.sampleFormat = paFloat32; /* 32 bit floating point output. */
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/* When you change this, also */
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/* adapt the callback routine! */
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outputParameters.suggestedLatency = Pa_GetDeviceInfo( outputParameters.device )
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->defaultLowOutputLatency; /* Low latency. */
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err = Pa_OpenStream( &stream,
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NULL, /* No input. */
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1024, /* frames per buffer */
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if (err != paNoError)
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err = Pa_StartStream( stream );
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if (err != paNoError)
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Pa_Sleep( NUM_SECONDS * 1000 );
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printf("CPULoad = %8.6f\n", Pa_GetStreamCpuLoad(stream));
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err = Pa_CloseStream( stream );
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Pa_Sleep( 250 ); /* Just a small silence. */
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/*******************************************************************/
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float amplitude = 4.0 / (1<<15);
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printf("PortAudio Test: output EXTREMELY QUIET sine wave with and without dithering.\n");
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/* initialise sinusoidal wavetable */
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for( i=0; i<TABLE_SIZE; i++ )
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DATA.sine[i] = (float) sin( ((double)i/(double)TABLE_SIZE) * M_PI * 2. );
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printf("\nNo treatment..\n"); fflush(stdout);
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err = PlaySine( &DATA, paClipOff | paDitherOff, amplitude );
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if( err < 0 ) goto done;
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printf("\nClip..\n");
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err = PlaySine( &DATA, paDitherOff, amplitude );
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if( err < 0 ) goto done;
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printf("\nClip and Dither..\n");
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err = PlaySine( &DATA, paNoFlag, amplitude );
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fprintf( stderr, "An error occured 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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err = 1; /* Though PlaySine() already called Pa_Terminate(), */
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} /* we may still call Pa_GetErrorText(). */
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printf("\n(Don't forget to turn the VOLUME DOWN after listening so carefully.)\n");
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return err; /* 0 or 1. */
added
removed
lib-src/portaudio-v19/test/patest_dither.c
