/* |
File: Pink.h |
Abstract: Pink.h |
Version: 1.0.1 |
|
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Copyright (C) 2014 Apple Inc. All Rights Reserved. |
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*/ |
|
class PinkFilter |
{ |
public: |
PinkFilter() {Reset();}; |
|
void Reset() {buf0=buf1=buf2=buf3=buf4=buf5=buf6=0.0;}; |
|
void Process( const float *inSourceP, |
float *inDestP, |
int inFramesToProcess, |
int inInputHop, |
int inOutputHop |
) |
{ |
register int n = inFramesToProcess; |
register const float *sourceP = inSourceP; |
register float *destP = inDestP; |
|
register int inputHop = inInputHop; |
register int outputHop = inOutputHop; |
|
while(n--) |
{ |
float white= *sourceP; |
sourceP += inputHop; |
|
// pink noise algorithim courtesy of |
// http://www.firstpr.com.au/dsp/pink-noise/ |
buf0= 0.99886 * buf0 + 0.0555179 * white; |
buf1= 0.99332 * buf1 + 0.0750759 * white; |
buf2= 0.96900 * buf2 + 0.1538520 * white; |
buf3= 0.86650 * buf3 + 0.3104856 * white; |
buf4= 0.55000 * buf4 + 0.5329522 * white; |
buf5= -0.7616 * buf5 + 0.0168980 * white; |
float pink=buf0 + buf1 + buf2 + buf3 + buf4 |
+ buf5 + buf6 + white * .5362; |
buf6= 0.115926 * white; |
|
*destP = pink; |
destP += outputHop; |
} |
}; |
|
|
|
private: |
float buf0; |
float buf1; |
float buf2; |
float buf3; |
float buf4; |
float buf5; |
float buf6; |
}; |
|
|
/* |
Pink filter: |
white=(whichever method you choose); |
buf0=0.997 * buf0 + 0.029591 * white; |
buf1=0.985 * buf1 + 0.032534 * white; |
buf2=0.950 * buf2 + 0.048056 * white; |
buf3=0.850 * buf3 + 0.090579 * white; |
|
buf4=0.620 * buf4 + 0.108990 * white; |
buf5=0.250 * buf5 + 0.255784 * white; |
pink=buf0 + buf1 + buf2 + buf3 + buf4 |
+ buf5; |
*/ |
|
#include "TRandom.h" |
#include "Biquad.h" |
|
class PinkNoiseGenerator |
{ |
public: |
PinkNoiseGenerator(Float32 inSampleRate ) |
{ |
nyquist = 0.5 * inSampleRate; |
rumbleFilter.GetHipassParams(10.0/*Hertz*/ / nyquist, 0.0 ); |
} |
|
void Render(Float32 *inBuffer, UInt32 inNumFrames, Float32 inVolume ) |
{ |
const Float32 kInv32768 = (1.0 / 32768.0) * 0.5; |
|
Float32 *destP = inBuffer; |
int n = inNumFrames; |
|
while(n--) |
{ |
SInt32 r = SInt32(GetRandomLong(65536) ) - 32768; |
Float32 sample = r * kInv32768 * inVolume; |
|
*destP++ = sample; |
} |
|
|
// filter "backwards" since kernel is in reverse order |
filter.Process( inBuffer, |
inBuffer, |
inNumFrames, |
1, |
1 |
); |
|
|
// Hipass rumble filter to remove potential skanky DC offset |
rumbleFilter.Process( inBuffer, |
inBuffer, |
inNumFrames, |
1, |
1 |
); |
} |
|
|
private: |
float nyquist; |
Biquad rumbleFilter; |
PinkFilter filter; |
}; |
