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