PortAudio: paex_pink.c Source File

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paex_pink.c
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1
19 /*
20 * $Id: paex_pink.c 1752 2011-09-08 03:21:55Z philburk $
21 *
22 * This program uses the PortAudio Portable Audio Library.
23 * For more information see: http://www.portaudio.com
24 * Copyright (c) 1999-2000 Ross Bencina and Phil Burk
25 *
26 * Permission is hereby granted, free of charge, to any person obtaining
27 * a copy of this software and associated documentation files
28 * (the "Software"), to deal in the Software without restriction,
29 * including without limitation the rights to use, copy, modify, merge,
30 * publish, distribute, sublicense, and/or sell copies of the Software,
31 * and to permit persons to whom the Software is furnished to do so,
32 * subject to the following conditions:
33 *
34 * The above copyright notice and this permission notice shall be
35 * included in all copies or substantial portions of the Software.
36 *
37 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
38 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
39 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
40 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
41 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
42 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
43 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
44 */
45
46 /*
47 * The text above constitutes the entire PortAudio license; however,
48 * the PortAudio community also makes the following non-binding requests:
49 *
50 * Any person wishing to distribute modifications to the Software is
51 * requested to send the modifications to the original developer so that
52 * they can be incorporated into the canonical version. It is also
53 * requested that these non-binding requests be included along with the
54 * license above.
55 */
56
57 #include <stdio.h>
58 #include <math.h>
59 #include "portaudio.h"
60
61 #define PINK_MAX_RANDOM_ROWS (30)
62 #define PINK_RANDOM_BITS (24)
63 #define PINK_RANDOM_SHIFT ((sizeof(long)*8)-PINK_RANDOM_BITS)
64
65 typedef struct
66 {
67 long pink_Rows[PINK_MAX_RANDOM_ROWS];
68 long pink_RunningSum; /* Used to optimize summing of generators. */
69 int pink_Index; /* Incremented each sample. */
70 int pink_IndexMask; /* Index wrapped by ANDing with this mask. */
71 float pink_Scalar; /* Used to scale within range of -1.0 to +1.0 */
72 }
73 PinkNoise;
74
75 /* Prototypes */
76 static unsigned long GenerateRandomNumber( void );
77 void InitializePinkNoise( PinkNoise *pink, int numRows );
78 float GeneratePinkNoise( PinkNoise *pink );
79
80 /************************************************************/
81 /* Calculate pseudo-random 32 bit number based on linear congruential method. */
82 static unsigned long GenerateRandomNumber( void )
83 {
84 /* Change this seed for different random sequences. */
85 static unsigned long randSeed = 22222;
86 randSeed = (randSeed * 196314165) + 907633515;
87 return randSeed;
88 }
89
90 /************************************************************/
91 /* Setup PinkNoise structure for N rows of generators. */
92 void InitializePinkNoise( PinkNoise *pink, int numRows )
93 {
94 int i;
95 long pmax;
96 pink->pink_Index = 0;
97 pink->pink_IndexMask = (1<<numRows) - 1;
98 /* Calculate maximum possible signed random value. Extra 1 for white noise always added. */
99 pmax = (numRows + 1) * (1<<(PINK_RANDOM_BITS-1));
100 pink->pink_Scalar = 1.0f / pmax;
101 /* Initialize rows. */
102 for( i=0; i<numRows; i++ ) pink->pink_Rows[i] = 0;
103 pink->pink_RunningSum = 0;
104 }
105
106 #define PINK_MEASURE
107 #ifdef PINK_MEASURE
108 float pinkMax = -999.0;
109 float pinkMin = 999.0;
110 #endif
111
112 /* Generate Pink noise values between -1.0 and +1.0 */
113 float GeneratePinkNoise( PinkNoise *pink )
114 {
115 long newRandom;
116 long sum;
117 float output;
118 /* Increment and mask index. */
119 pink->pink_Index = (pink->pink_Index + 1) & pink->pink_IndexMask;
120 /* If index is zero, don't update any random values. */
121 if( pink->pink_Index != 0 )
122 {
123 /* Determine how many trailing zeros in PinkIndex. */
124 /* This algorithm will hang if n==0 so test first. */
125 int numZeros = 0;
126 int n = pink->pink_Index;
127 while( (n & 1) == 0 )
128 {
129 n = n >> 1;
130 numZeros++;
131 }
132 /* Replace the indexed ROWS random value.
133 * Subtract and add back to RunningSum instead of adding all the random
134 * values together. Only one changes each time.
135 */
136 pink->pink_RunningSum -= pink->pink_Rows[numZeros];
137 newRandom = ((long)GenerateRandomNumber()) >> PINK_RANDOM_SHIFT;
138 pink->pink_RunningSum += newRandom;
139 pink->pink_Rows[numZeros] = newRandom;
140 }
141
142 /* Add extra white noise value. */
143 newRandom = ((long)GenerateRandomNumber()) >> PINK_RANDOM_SHIFT;
144 sum = pink->pink_RunningSum + newRandom;
145 /* Scale to range of -1.0 to 0.9999. */
146 output = pink->pink_Scalar * sum;
147 #ifdef PINK_MEASURE
148 /* Check Min/Max */
149 if( output > pinkMax ) pinkMax = output;
150 else if( output < pinkMin ) pinkMin = output;
151 #endif
152 return output;
153 }
154
155 /*******************************************************************/
156 #define PINK_TEST
157 #ifdef PINK_TEST
158
159 /* Context for callback routine. */
160 typedef struct
161 {
162 PinkNoise leftPink;
163 PinkNoise rightPink;
164 unsigned int sampsToGo;
165 }
166 paTestData;
167
168 /* This routine will be called by the PortAudio engine when audio is needed.
169 ** It may called at interrupt level on some machines so don't do anything
170 ** that could mess up the system like calling malloc() or free().
171 */
172 static int patestCallback(const void* inputBuffer,
173 void* outputBuffer,
174 unsigned long framesPerBuffer,
175 const PaStreamCallbackTimeInfo* timeInfo,
176 PaStreamCallbackFlags statusFlags,
177 void* userData)
178 {
179 int finished;
180 int i;
181 int numFrames;
182 paTestData *data = (paTestData*)userData;
183 float *out = (float*)outputBuffer;
184 (void) inputBuffer; /* Prevent "unused variable" warnings. */
185
186 /* Are we almost at end. */
187 if( data->sampsToGo < framesPerBuffer )
188 {
189 numFrames = data->sampsToGo;
190 finished = 1;
191 }
192 else
193 {
194 numFrames = framesPerBuffer;
195 finished = 0;
196 }
197 for( i=0; i<numFrames; i++ )
198 {
199 *out++ = GeneratePinkNoise( &data->leftPink );
200 *out++ = GeneratePinkNoise( &data->rightPink );
201 }
202 data->sampsToGo -= numFrames;
203 return finished;
204 }
205
206 /*******************************************************************/
207 int main(void);
208 int main(void)
209 {
210 PaStream* stream;
211 PaError err;
212 paTestData data;
213 PaStreamParameters outputParameters;
214 int totalSamps;
215 static const double SR = 44100.0;
216 static const int FPB = 2048; /* Frames per buffer: 46 ms buffers. */
217
218 /* Initialize two pink noise signals with different numbers of rows. */
219 InitializePinkNoise( &data.leftPink, 12 );
220 InitializePinkNoise( &data.rightPink, 16 );
221
222 /* Look at a few values. */
223 {
224 int i;
225 float pink;
226 for( i=0; i<20; i++ )
227 {
228 pink = GeneratePinkNoise( &data.leftPink );
229 printf("Pink = %f\n", pink );
230 }
231 }
232
233 data.sampsToGo = totalSamps = (int)(60.0 * SR); /* Play a whole minute. */
234 err = Pa_Initialize();
235 if( err != paNoError ) goto error;
236
237 /* Open a stereo PortAudio stream so we can hear the result. */
238 outputParameters.device = Pa_GetDefaultOutputDevice(); /* Take the default output device. */
239 if (outputParameters.device == paNoDevice) {
240 fprintf(stderr,"Error: No default output device.\n");
241 goto error;
242 }
243 outputParameters.channelCount = 2; /* Stereo output, most likely supported. */
244 outputParameters.hostApiSpecificStreamInfo = NULL;
245 outputParameters.sampleFormat = paFloat32; /* 32 bit floating point output. */
246 outputParameters.suggestedLatency =
247 Pa_GetDeviceInfo(outputParameters.device)->defaultLowOutputLatency;
248 err = Pa_OpenStream(&stream,
249 NULL, /* No input. */
250 &outputParameters,
251 SR, /* Sample rate. */
252 FPB, /* Frames per buffer. */
253 paClipOff, /* we won't output out of range samples so don't bother clipping them */
254 patestCallback,
255 &data);
256 if( err != paNoError ) goto error;
257
258 err = Pa_StartStream( stream );
259 if( err != paNoError ) goto error;
260
261 printf("Stereo pink noise for one minute...\n");
262
263 while( ( err = Pa_IsStreamActive( stream ) ) == 1 ) Pa_Sleep(100);
264 if( err < 0 ) goto error;
265
266 err = Pa_CloseStream( stream );
267 if( err != paNoError ) goto error;
268 #ifdef PINK_MEASURE
269 printf("Pink min = %f, max = %f\n", pinkMin, pinkMax );
270 #endif
271 Pa_Terminate();
272 return 0;
273 error:
274 Pa_Terminate();
275 fprintf( stderr, "An error occured while using the portaudio stream\n" );
276 fprintf( stderr, "Error number: %d\n", err );
277 fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
278 return 0;
279 }
280 #endif /* PINK_TEST */