Spatializer audio filter, work for Google Summer of Code, by Isaac Biodun...

Spatializer audio filter, work for Google Summer of Code, by Isaac Biodun Osunkunle: osunkunle --- gmail.com
This is the first part of his work.

modules/audio_filter/spatializer/Modules.am

+SOURCES_spatializer = spatializer.cpp \
+    allpass.cpp allpass.hpp comb.cpp comb.hpp \
+    denormals.h tuning.h revmodel.cpp revmodel.hpp
+

modules/audio_filter/spatializer/allpass.cpp

+// Allpass filter implementation
+//
+// Written by Jezar at Dreampoint, June 2000
+// http://www.dreampoint.co.uk
+// This code is public domain
+
+#include "allpass.hpp"
+
+allpass::allpass()
+{
+	bufidx = 0;
+}
+
+void allpass::setbuffer(float *buf, int size) 
+{
+	buffer = buf; 
+	bufsize = size;
+}
+
+void allpass::mute()
+{
+	for (int i=0; i<bufsize; i++)
+		buffer[i]=0;
+}
+
+void allpass::setfeedback(float val) 
+{
+	feedback = val;
+}
+
+float allpass::getfeedback() 
+{
+	return feedback;
+}
+
+//ends
\ No newline at end of file

modules/audio_filter/spatializer/allpass.hpp

+// Allpass filter declaration
+//
+// Written by Jezar at Dreampoint, June 2000
+// http://www.dreampoint.co.uk
+// This code is public domain
+
+#ifndef _allpass_
+#define _allpass_
+#include "denormals.h"
+
+class allpass
+{
+public:
+        allpass();
+	void	setbuffer(float *buf, int size);
+	inline  float	process(float inp);
+	void	mute();
+	void	setfeedback(float val);
+	float	getfeedback();
+// private:
+	float	feedback;
+	float	*buffer;
+	int	bufsize;
+	int	bufidx;
+};
+
+
+// Big to inline - but crucial for speed
+
+inline float allpass::process(float input)
+{
+	float output;
+	float bufout;
+	
+	bufout = buffer[bufidx];
+	undenormalise(bufout);
+	
+	output = -input + bufout;
+	buffer[bufidx] = input + (bufout*feedback);
+
+	if(++bufidx>=bufsize) bufidx = 0;
+
+	return output;
+}
+
+#endif//_allpass
+
+//ends

modules/audio_filter/spatializer/comb.cpp

+// Comb filter implementation
+//
+// Written by Jezar at Dreampoint, June 2000
+// http://www.dreampoint.co.uk
+// This code is public domain
+
+#include "comb.hpp"
+
+comb::comb()
+{
+	filterstore = 0;
+	bufidx = 0;
+}
+
+void comb::setbuffer(float *buf, int size) 
+{
+	buffer = buf; 
+	bufsize = size;
+}
+
+void comb::mute()
+{
+	for (int i=0; i<bufsize; i++)
+		buffer[i]=0;
+}
+
+void comb::setdamp(float val) 
+{
+	damp1 = val; 
+	damp2 = 1-val;
+}
+
+float comb::getdamp() 
+{
+	return damp1;
+}
+
+void comb::setfeedback(float val) 
+{
+	feedback = val;
+}
+
+float comb::getfeedback() 
+{
+	return feedback;
+}
+
+// ends

modules/audio_filter/spatializer/comb.hpp

+// Comb filter class declaration
+//
+// Written by Jezar at Dreampoint, June 2000
+// http://www.dreampoint.co.uk
+// This code is public domain
+
+#ifndef _comb_
+#define _comb_
+
+#include "denormals.h"
+
+class comb
+{
+public:
+	comb();
+	void	setbuffer(float *buf, int size);
+	inline  float	process(float inp);
+	void	mute();
+	void	setdamp(float val);
+	float	getdamp();
+	void	setfeedback(float val);
+	float	getfeedback();
+private:
+	float	feedback;
+	float	filterstore;
+	float	damp1;
+	float	damp2;
+	float	*buffer;
+	int	bufsize;
+	int	bufidx;
+};
+
+
+// Big to inline - but crucial for speed
+
+inline float comb::process(float input)
+{
+	float output;
+
+	output = buffer[bufidx];
+	undenormalise(output);
+
+	filterstore = (output*damp2) + (filterstore*damp1);
+	undenormalise(filterstore);
+
+	buffer[bufidx] = input + (filterstore*feedback);
+
+	if(++bufidx>=bufsize) bufidx = 0;
+
+	return output;
+}
+
+#endif //_comb_
+
+//ends

modules/audio_filter/spatializer/denormals.h

+// Macro for killing denormalled numbers
+//
+// Written by Jezar at Dreampoint, June 2000
+// http://www.dreampoint.co.uk
+// Based on IS_DENORMAL macro by Jon Watte
+// This code is public domain
+
+#ifndef _denormals_
+#define _denormals_
+
+#define undenormalise(sample) if(((*(unsigned int*)&sample)&0x7f800000)==0) sample=0.0f
+
+#endif//_denormals_
+
+//ends

modules/audio_filter/spatializer/revmodel.cpp

+// Reverb model implementation
+// 
+// 
+// Google Summer of Code 2007
+// 
+// Authors: Biodun Osunkunle <biodun@videolan.org> 
+// 
+// Mentor : Jean-Baptiste Kempf <jb@videolan.org>
+//
+// Original written by Jezar at Dreampoint, June 2000
+
+// This code is public domain
+
+#include "revmodel.hpp"
+#include <stdlib.h>
+
+revmodel::revmodel()
+{
+	// Tie the components to their buffers
+	combL[0].setbuffer(bufcombL1,combtuningL1);
+	combR[0].setbuffer(bufcombR1,combtuningR1);
+	combL[1].setbuffer(bufcombL2,combtuningL2);
+	combR[1].setbuffer(bufcombR2,combtuningR2);
+	combL[2].setbuffer(bufcombL3,combtuningL3);
+	combR[2].setbuffer(bufcombR3,combtuningR3);
+	combL[3].setbuffer(bufcombL4,combtuningL4);
+	combR[3].setbuffer(bufcombR4,combtuningR4);
+	combL[4].setbuffer(bufcombL5,combtuningL5);
+	combR[4].setbuffer(bufcombR5,combtuningR5);
+	combL[5].setbuffer(bufcombL6,combtuningL6);
+	combR[5].setbuffer(bufcombR6,combtuningR6);
+	combL[6].setbuffer(bufcombL7,combtuningL7);
+	combR[6].setbuffer(bufcombR7,combtuningR7);
+	combL[7].setbuffer(bufcombL8,combtuningL8);
+	combR[7].setbuffer(bufcombR8,combtuningR8);
+	allpassL[0].setbuffer(bufallpassL1,allpasstuningL1);
+	allpassR[0].setbuffer(bufallpassR1,allpasstuningR1);
+	allpassL[1].setbuffer(bufallpassL2,allpasstuningL2);
+	allpassR[1].setbuffer(bufallpassR2,allpasstuningR2);
+	allpassL[2].setbuffer(bufallpassL3,allpasstuningL3);
+	allpassR[2].setbuffer(bufallpassR3,allpasstuningR3);
+	allpassL[3].setbuffer(bufallpassL4,allpasstuningL4);
+	allpassR[3].setbuffer(bufallpassR4,allpasstuningR4);
+
+	// Set default values
+	allpassL[0].setfeedback(0.5f);
+	allpassR[0].setfeedback(0.5f);
+	allpassL[1].setfeedback(0.5f);
+	allpassR[1].setfeedback(0.5f);
+	allpassL[2].setfeedback(0.5f);
+	allpassR[2].setfeedback(0.5f);
+	allpassL[3].setfeedback(0.5f);
+	allpassR[3].setfeedback(0.5f);
+	setwet(initialwet);
+	setroomsize(initialroom);
+	setdry(initialdry);
+	setdamp(initialdamp);
+	setwidth(initialwidth);
+	setmode(initialmode);
+
+	// Buffer will be full of rubbish - so we MUST mute them
+	mute();
+}
+
+void revmodel::mute()
+{
+	int i;
+	if (getmode() >= freezemode)
+		return;
+
+	for (i = 0 ; i < numcombs ; i++)
+	{
+		combL[i].mute();
+		combR[i].mute();
+	}
+	for (i=0;i<numallpasses;i++)
+	{
+		allpassL[i].mute();
+		allpassR[i].mute();
+	}
+}
+
+void revmodel::processreplace(float *inputL, float *outputL, long numsamples, int skip)
+{
+	float outL,outR,input;
+	float inputR;
+	int i;
+
+	outL = outR = 0;
+        if (skip > 1) 
+           inputR = inputL[1];
+        else 
+           inputR = inputL[0];         
+		input = (inputL[0] + inputR) * gain;
+		
+		// Accumulate comb filters in parallel
+		for(i=0; i<numcombs; i++)
+		{
+			outL += combL[i].process(input);
+			outR += combR[i].process(input);
+		}
+
+		// Feed through allpasses in series
+		for(i=0; i<numallpasses; i++)
+		{
+			outL = allpassL[i].process(outL);
+			outR = allpassR[i].process(outR);
+		}
+
+		// Calculate output REPLACING anything already there
+		outputL[0] = (outL*wet1 + outR*wet2 + inputR*dry);
+           if (skip > 1)
+		outputL[1] = (outR*wet1 + outL*wet2 + inputR*dry);
+}
+
+void revmodel::processmix(float *inputL, float *outputL, long numsamples, int skip)
+{
+	float outL,outR,input;
+	float inputR;
+	int i;
+
+	outL = outR = 0;
+        if (skip > 1) 
+           inputR = inputL[1];
+        else 
+           inputR = inputL[0];         
+		input = (inputL[0] + inputR) * gain;
+		
+		// Accumulate comb filters in parallel
+		for(i=0; i<numcombs; i++)
+		{
+			outL += combL[i].process(input);
+			outR += combR[i].process(input);
+		}
+
+		// Feed through allpasses in series
+		for(i=0; i<numallpasses; i++)
+		{
+			outL = allpassL[i].process(outL);
+			outR = allpassR[i].process(outR);
+		}
+
+		// Calculate output REPLACING anything already there
+		outputL[0] += (outL*wet1 + outR*wet2 + inputR*dry);
+           if (skip > 1)
+		outputL[1] += (outR*wet1 + outL*wet2 + inputR*dry);
+}
+
+void revmodel::update()
+{
+// Recalculate internal values after parameter change
+
+	int i;
+
+	wet1 = wet*(width/2 + 0.5f);
+	wet2 = wet*((1-width)/2);
+
+	if (mode >= freezemode)
+	{
+		roomsize1 = 1;
+		damp1 = 0;
+		gain = muted;
+	}
+	else
+	{
+		roomsize1 = roomsize;
+		damp1 = damp;
+		gain = fixedgain;
+	}
+
+	for(i=0; i<numcombs; i++)
+	{
+		combL[i].setfeedback(roomsize1);
+		combR[i].setfeedback(roomsize1);
+	}
+
+	for(i=0; i<numcombs; i++)
+	{
+		combL[i].setdamp(damp1);
+		combR[i].setdamp(damp1);
+	}
+}
+
+// The following get/set functions are not inlined, because
+// speed is never an issue when calling them, and also
+// because as you develop the reverb model, you may
+// wish to take dynamic action when they are called.
+
+void revmodel::setroomsize(float value)
+{
+	roomsize = (value*scaleroom) + offsetroom;
+	update();
+}
+
+float revmodel::getroomsize()
+{
+	return (roomsize-offsetroom)/scaleroom;
+}
+
+void revmodel::setdamp(float value)
+{
+	damp = value*scaledamp;
+	update();
+}
+
+float revmodel::getdamp()
+{
+	return damp/scaledamp;
+}
+
+void revmodel::setwet(float value)
+{
+	wet = value*scalewet;
+	update();
+}
+
+float revmodel::getwet()
+{
+	return wet/scalewet;
+}
+
+void revmodel::setdry(float value)
+{
+	dry = value*scaledry;
+}
+
+float revmodel::getdry()
+{
+	return dry/scaledry;
+}
+
+void revmodel::setwidth(float value)
+{
+	width = value;
+	update();
+}
+
+float revmodel::getwidth()
+{
+	return width;
+}
+
+void revmodel::setmode(float value)
+{
+	mode = value;
+	update();
+}
+
+float revmodel::getmode()
+{
+	if (mode >= freezemode)
+		return 1;
+	else
+		return 0;
+}
+
+//ends

modules/audio_filter/spatializer/revmodel.hpp

+// Reverb model declaration
+//
+// Google Summer of Code 2007
+// 
+// Authors: Biodun Osunkunle <biodun@videolan.org> 
+// 
+// Mentor : Jean-Baptiste Kempf <jb@videolan.org>
+//
+// Original written by Jezar at Dreampoint, June 2000
+
+#ifndef _revmodel_
+#define _revmodel_
+
+#include "comb.hpp"
+#include "allpass.hpp"
+#include "tuning.h"
+
+class revmodel
+{
+public:
+	        revmodel();
+	void	mute();
+	void	processreplace(float *inputL, float *outputL, long numsamples, int skip);
+	void    processmix(float *inputL, float *outputL, long numsamples, int skip);
+	void	setroomsize(float value);
+	float	getroomsize();
+	void	setdamp(float value);
+	float	getdamp();
+	void	setwet(float value);
+	float	getwet();
+	void	setdry(float value);
+	float	getdry();
+	void	setwidth(float value);
+	float	getwidth();
+	void	setmode(float value);
+	float	getmode();
+private:
+	void	update();
+private:
+	float	gain;
+	float	roomsize,roomsize1;
+	float	damp,damp1;
+	float	wet,wet1,wet2;
+	float	dry;
+	float	width;
+	float	mode;
+
+// The following are all declared inline 
+// to remove the need for dynamic allocation
+// with its subsequent error-checking messiness
+
+// Comb filters
+	comb	combL[numcombs];
+	comb	combR[numcombs];
+
+	// Allpass filters
+	allpass	allpassL[numallpasses];
+	allpass	allpassR[numallpasses];
+
+	// Buffers for the combs
+	float	bufcombL1[combtuningL1];
+	float	bufcombR1[combtuningR1];
+	float	bufcombL2[combtuningL2];
+	float	bufcombR2[combtuningR2];
+	float	bufcombL3[combtuningL3];
+	float	bufcombR3[combtuningR3];
+	float	bufcombL4[combtuningL4];
+	float	bufcombR4[combtuningR4];
+	float	bufcombL5[combtuningL5];
+	float	bufcombR5[combtuningR5];
+	float	bufcombL6[combtuningL6];
+	float	bufcombR6[combtuningR6];
+	float	bufcombL7[combtuningL7];
+	float	bufcombR7[combtuningR7];
+	float	bufcombL8[combtuningL8];
+	float	bufcombR8[combtuningR8];
+
+	// Buffers for the allpasses
+	float	bufallpassL1[allpasstuningL1];
+	float	bufallpassR1[allpasstuningR1];
+	float	bufallpassL2[allpasstuningL2];
+	float	bufallpassR2[allpasstuningR2];
+	float	bufallpassL3[allpasstuningL3];
+	float	bufallpassR3[allpasstuningR3];
+	float	bufallpassL4[allpasstuningL4];
+	float	bufallpassR4[allpasstuningR4];
+};
+
+#endif//_revmodel_
+
+//ends

modules/audio_filter/spatializer/tuning.h

+// Reverb model tuning values
+//
+// Written by Jezar at Dreampoint, June 2000
+// http://www.dreampoint.co.uk
+// This code is public domain
+
+#ifndef _tuning_
+#define _tuning_
+
+const int   numcombs	        = 8;
+const int   numallpasses	= 4;
+const float muted		= 0;
+const float fixedgain	        = 0.005f;
+const float scalewet		= 3;
+const float scaledry		= 2;
+const float scaledamp		= 0.4f;
+const float scaleroom		= 0.28f;
+const float offsetroom		= 0.7f;
+const float initialroom		= 0.5f;
+const float initialdamp		= 0.5f;
+const float initialwet		= 1/scalewet;
+const float initialdry		= 0;
+const float initialwidth	= 1;
+const float initialmode		= 0;
+const float freezemode		= 0.5f;
+const int   stereospread	= 23;
+
+// These values assume 44.1KHz sample rate
+// they will probably be OK for 48KHz sample rate
+// but would need scaling for 96KHz (or other) sample rates.
+// The values were obtained by listening tests.
+const int combtuningL1		= 1116;
+const int combtuningR1		= 1116+stereospread;
+const int combtuningL2		= 1188;
+const int combtuningR2		= 1188+stereospread;
+const int combtuningL3		= 1277;
+const int combtuningR3		= 1277+stereospread;
+const int combtuningL4		= 1356;
+const int combtuningR4		= 1356+stereospread;
+const int combtuningL5		= 1422;
+const int combtuningR5		= 1422+stereospread;
+const int combtuningL6		= 1491;
+const int combtuningR6		= 1491+stereospread;
+const int combtuningL7		= 1557;
+const int combtuningR7		= 1557+stereospread;
+const int combtuningL8		= 1617;
+const int combtuningR8		= 1617+stereospread;
+const int allpasstuningL1	= 556;
+const int allpasstuningR1	= 556+stereospread;
+const int allpasstuningL2	= 441;
+const int allpasstuningR2	= 441+stereospread;
+const int allpasstuningL3	= 341;
+const int allpasstuningR3	= 341+stereospread;
+const int allpasstuningL4	= 225;
+const int allpasstuningR4	= 225+stereospread;
+
+#endif//_tuning_
+
+//ends
+