281 lines
9.7 KiB
C
281 lines
9.7 KiB
C
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/** @file paex_pink.c
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@ingroup examples_src
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@brief Generate Pink Noise using Gardner method.
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Optimization suggested by James McCartney uses a tree
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to select which random value to replace.
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<pre>
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x x x x x x x x x x x x x x x x
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x x x x x x x x
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x x x x
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x x
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x
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</pre>
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Tree is generated by counting trailing zeros in an increasing index.
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When the index is zero, no random number is selected.
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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 PINK_MAX_RANDOM_ROWS (30)
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#define PINK_RANDOM_BITS (24)
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#define PINK_RANDOM_SHIFT ((sizeof(long)*8)-PINK_RANDOM_BITS)
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typedef struct
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{
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long pink_Rows[PINK_MAX_RANDOM_ROWS];
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long pink_RunningSum; /* Used to optimize summing of generators. */
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int pink_Index; /* Incremented each sample. */
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int pink_IndexMask; /* Index wrapped by ANDing with this mask. */
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float pink_Scalar; /* Used to scale within range of -1.0 to +1.0 */
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}
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PinkNoise;
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/* Prototypes */
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static unsigned long GenerateRandomNumber( void );
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void InitializePinkNoise( PinkNoise *pink, int numRows );
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float GeneratePinkNoise( PinkNoise *pink );
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/************************************************************/
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/* Calculate pseudo-random 32 bit number based on linear congruential method. */
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static unsigned long GenerateRandomNumber( void )
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{
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/* Change this seed for different random sequences. */
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static unsigned long randSeed = 22222;
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randSeed = (randSeed * 196314165) + 907633515;
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return randSeed;
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}
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/************************************************************/
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/* Setup PinkNoise structure for N rows of generators. */
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void InitializePinkNoise( PinkNoise *pink, int numRows )
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{
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int i;
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long pmax;
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pink->pink_Index = 0;
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pink->pink_IndexMask = (1<<numRows) - 1;
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/* Calculate maximum possible signed random value. Extra 1 for white noise always added. */
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pmax = (numRows + 1) * (1<<(PINK_RANDOM_BITS-1));
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pink->pink_Scalar = 1.0f / pmax;
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/* Initialize rows. */
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for( i=0; i<numRows; i++ ) pink->pink_Rows[i] = 0;
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pink->pink_RunningSum = 0;
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}
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#define PINK_MEASURE
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#ifdef PINK_MEASURE
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float pinkMax = -999.0;
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float pinkMin = 999.0;
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#endif
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/* Generate Pink noise values between -1.0 and +1.0 */
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float GeneratePinkNoise( PinkNoise *pink )
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{
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long newRandom;
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long sum;
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float output;
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/* Increment and mask index. */
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pink->pink_Index = (pink->pink_Index + 1) & pink->pink_IndexMask;
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/* If index is zero, don't update any random values. */
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if( pink->pink_Index != 0 )
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{
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/* Determine how many trailing zeros in PinkIndex. */
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/* This algorithm will hang if n==0 so test first. */
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int numZeros = 0;
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int n = pink->pink_Index;
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while( (n & 1) == 0 )
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{
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n = n >> 1;
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numZeros++;
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}
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/* Replace the indexed ROWS random value.
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* Subtract and add back to RunningSum instead of adding all the random
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* values together. Only one changes each time.
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*/
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pink->pink_RunningSum -= pink->pink_Rows[numZeros];
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newRandom = ((long)GenerateRandomNumber()) >> PINK_RANDOM_SHIFT;
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pink->pink_RunningSum += newRandom;
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pink->pink_Rows[numZeros] = newRandom;
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}
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/* Add extra white noise value. */
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newRandom = ((long)GenerateRandomNumber()) >> PINK_RANDOM_SHIFT;
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sum = pink->pink_RunningSum + newRandom;
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/* Scale to range of -1.0 to 0.9999. */
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output = pink->pink_Scalar * sum;
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#ifdef PINK_MEASURE
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/* Check Min/Max */
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if( output > pinkMax ) pinkMax = output;
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else if( output < pinkMin ) pinkMin = output;
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#endif
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return output;
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}
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/*******************************************************************/
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#define PINK_TEST
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#ifdef PINK_TEST
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/* Context for callback routine. */
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typedef struct
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{
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PinkNoise leftPink;
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PinkNoise rightPink;
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unsigned int sampsToGo;
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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,
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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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int finished;
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int i;
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int numFrames;
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paTestData *data = (paTestData*)userData;
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float *out = (float*)outputBuffer;
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(void) inputBuffer; /* Prevent "unused variable" warnings. */
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/* Are we almost at end. */
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if( data->sampsToGo < framesPerBuffer )
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{
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numFrames = data->sampsToGo;
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finished = 1;
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}
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else
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{
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numFrames = framesPerBuffer;
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finished = 0;
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}
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for( i=0; i<numFrames; i++ )
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{
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*out++ = GeneratePinkNoise( &data->leftPink );
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*out++ = GeneratePinkNoise( &data->rightPink );
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}
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data->sampsToGo -= numFrames;
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return finished;
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}
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/*******************************************************************/
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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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paTestData data;
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PaStreamParameters outputParameters;
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int totalSamps;
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static const double SR = 44100.0;
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static const int FPB = 2048; /* Frames per buffer: 46 ms buffers. */
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/* Initialize two pink noise signals with different numbers of rows. */
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InitializePinkNoise( &data.leftPink, 12 );
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InitializePinkNoise( &data.rightPink, 16 );
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/* Look at a few values. */
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{
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int i;
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float pink;
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for( i=0; i<20; i++ )
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{
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pink = GeneratePinkNoise( &data.leftPink );
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printf("Pink = %f\n", pink );
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}
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}
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data.sampsToGo = totalSamps = (int)(60.0 * SR); /* Play a whole minute. */
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err = Pa_Initialize();
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if( err != paNoError ) goto error;
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/* Open a stereo PortAudio stream so we can hear the result. */
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outputParameters.device = Pa_GetDefaultOutputDevice(); /* Take the default output device. */
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if (outputParameters.device == paNoDevice) {
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fprintf(stderr,"Error: No default output device.\n");
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goto error;
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}
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outputParameters.channelCount = 2; /* Stereo output, most likely supported. */
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outputParameters.hostApiSpecificStreamInfo = NULL;
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outputParameters.sampleFormat = paFloat32; /* 32 bit floating point output. */
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outputParameters.suggestedLatency =
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Pa_GetDeviceInfo(outputParameters.device)->defaultLowOutputLatency;
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err = Pa_OpenStream(&stream,
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NULL, /* No input. */
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&outputParameters,
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SR, /* Sample rate. */
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FPB, /* Frames per buffer. */
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paClipOff, /* we won't output out of range samples so don't bother clipping them */
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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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printf("Stereo pink noise for one minute...\n");
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while( ( err = Pa_IsStreamActive( stream ) ) == 1 ) Pa_Sleep(100);
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if( err < 0 ) goto error;
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err = Pa_CloseStream( stream );
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if( err != paNoError ) goto error;
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#ifdef PINK_MEASURE
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printf("Pink min = %f, max = %f\n", pinkMin, pinkMax );
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#endif
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Pa_Terminate();
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return 0;
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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 0;
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}
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#endif /* PINK_TEST */
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