Fork Code: Convolution reverb and impulse responses

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// Posted by Paul Miller
// https://listarc.cal.bham.ac.uk/lists/sc-users-2016/msg52187.html

//  code for building & testing IRs

// setup
(
s.waitForBoot({
	{
		// init
		// free old buffers
		if (a.notNil, {
			if (a.buffer.notNil, {
				a.buffer.free;
			});
			if (a.target.notNil, {
				a.target.free;
			});
			if (a.irspectrum.notNil, {
				a.irspectrum.free;
			});
		});
		a = (); // settings dict
		//fft
		a.fftsize = 2048;

		// set target buffer for testing convolution with
		a.target= Buffer.read(s, Platform.resourceDir +/+ "sounds/a11wlk01.wav");

		// fill buffer using one of the following Examples:

		/*
		// ======= EX1 - create IR using dust & noise ======
		*/
		// CHANGE THESE SETTINGS:
		a.bufferTime = 3; // time in secs for new IR
		a.densityMin = 50; // min/max density of reflections
		a.densityMax = 500;
		a.filterFreqMin = 100; // min/max freq for filter sweep
		a.filterFreqMax = 8000;
		if (a.buffer.notNil, {
			a.buffer.free;
		});
		a.buffer = Buffer.alloc(s, s.sampleRate * a.bufferTime, 1);
		s.sync;
		// write into the buffer with a BufWr
		y = {
			var sourceVolEnv, filterFreqEnv, densityEnv, source, filterFunc, outSound;

			// CHANGE ENVELOPES, SOURCE & FILTER SETTINGS

			//sourceVolEnv = EnvGen.kr(Env([1, 0], [a.bufferTime], -3), doneAction: 2);
			//sourceVolEnv = EnvGen.kr(Env([0, 1], [a.bufferTime], 3), doneAction: 2);  // reverse env
			sourceVolEnv = EnvGen.kr(Env([0.2, 1], [a.bufferTime], 6), doneAction: 2);  // reverse env

			// filterFreqEnv = EnvGen.kr(Env([1, 0], [a.bufferTime], -2),
			// levelScale: (a.filterFreqMax - a.filterFreqMin), levelBias: a.filterFreqMin, doneAction: 0);
			filterFreqEnv = EnvGen.kr(Env([0, 1], [a.bufferTime], 6),
				levelScale: (a.filterFreqMax - a.filterFreqMin), levelBias: a.filterFreqMin, doneAction: 0);  // reverse env

			// densityEnv = EnvGen.kr(Env([0, 1], [a.bufferTime], 2),
			// levelScale: (a.densityMax - a.densityMin), levelBias: a.densityMin, doneAction: 0);
			densityEnv = EnvGen.kr(Env([1, 0], [a.bufferTime], -2),
				levelScale: (a.densityMax - a.densityMin), levelBias: a.densityMin, doneAction: 0);  // reverse env

			source = Dust.ar(densityEnv, 0.5) * WhiteNoise.ar;
			// source = Dust.ar(densityEnv, 0.5) * PinkNoise.ar;
			// source = Dust.ar(densityEnv, 0.5) * GrayNoise.ar;

			// filterFunc = {arg in, freq; LPF.ar(in, freq) };
			// filterFunc = {arg in, freq; HPF.ar(in, freq) };
			filterFunc = {arg in, freq;
				var allPass;
				//LPF.ar(in + AllpassC.ar(in, 0.1, 0.01, 0.5, mul: 0.75), freq);
				//LPF.ar(in + AllpassC.ar(in, 0.1, 0.1, 0.5, mul: 0.75), freq);
				//LPF.ar(in + AllpassC.ar(in, 0.01, XLine.kr(0.0001, 0.01, a.bufferTime), 0.2), freq);
				LPF.ar(in + AllpassC.ar(in * 0.5, 0.2, XLine.kr(0.001, 0.2, a.bufferTime), 0.5, mul: 0.5), freq);
			};

			outSound = filterFunc.value(sourceVolEnv * source, filterFreqEnv) * 100 / densityEnv;  // adjust volume with density

			// record buffer
			BufWr.ar(outSound, a.buffer, Phasor.ar(0, BufRateScale.kr(a.buffer), 0,
				BufFrames.kr(a.buffer)), loop: 0);

			outSound ! 2;
		}.play;
		// =======

		/*
		// ======= EX2 - load file from disk - MONO ONLY    ======
		if (a.buffer.notNil, {
			a.buffer.free;
		});
		a.buffer = Buffer.read(s, "/path/to/monoSoundFile.wav");  // e.g.
		//a.buffer = Buffer.read(s, "/Users/paul/TESTING/TestSamples/_impulses/SavedImpulse_20160831222540.aif");
		// =======
		*/


		/*
		// ======= EX3 - load file from disk & reverse it - MONO ONLY    ======
		if (a.buffer.notNil, {
			a.buffer.free;
		});
		// a.buffer = Buffer.read(s, "/path/to/monoSoundFile.wav");  // e.g.
		// a.buffer = Buffer.read(s, "/Users/paul/TESTING/TestSamples/_impulses/LexiconHallMono1.wav");
		a.buffer = Buffer.read(s, "/Users/paul/TESTING/TestSamples/_impulses/FactoryHallMono.wav");
		s.sync;
		a.buffer.loadToFloatArray(action: { arg array; a.floatArray = array.reverse; });
		s.sync;
		2.wait;
		a.buffer.free;
		a.buffer = Buffer.loadCollection(s, a.floatArray);
		*/
		// =======


		/*
		//  =======  EX4 - build buffer from floatArray - taken from PartConv help file
		// synthesise the honourable 'Dan Stowell' impulse response
		a.ir = ([1] ++0.dup(100) ++ ((1, 0.99998 .. 0).collect{|f| f =
		f.squared.squared; f = if(f.coin){0}{f.squared}; f =
		if(0.5.coin){0-f}{f} } * 0.1)
		).normalizeSum;
		a.ir = a.ir.reverse; // added for backwards reverb
		if (a.buffer.notNil, {
		a.buffer.free;
		});
		a.buffer = Buffer.loadCollection(s, a.ir);
		// a.ir.plot;
		*/
		// =======


		s.sync;
		"Setup Completed".postln;

	}.fork;
});
)
//////////////////////////////////////////////////////

// prepare irspectrum buffer
(
	{
		s.sync;
		a.bufsize = PartConv.calcBufSize(a.fftsize, a.buffer);
		if (a.irspectrum.notNil, {
			a.irspectrum.free;
		});
		a.irspectrum = Buffer.alloc(s, a.bufsize, 1);
		a.irspectrum.preparePartConv(a.buffer, a.fftsize);
		s.sync;
		"Prepare Buffer Completed".postln;
	}.fork;
)
//////////////////////////////////////////////////////


// examples to use the IR - all are mono, but duplicated in left/right speaker (using ! 2)

// convolve with target soundfile
(
{ var input, convLevel = 0.6;
	input = PlayBuf.ar(1, a.target.bufnum, loop:1);
	Out.ar(0, (convLevel * PartConv.ar(input, a.fftsize, a.irspectrum.bufnum, 0.5)) ! 2);
}.play;
)

// convolve with target soundfile adding  input
(
{ var input, delayTime, inputDelay, inputLevel = 0.5, convLevel = 0.5;
	input = PlayBuf.ar(1, a.target, loop:1);
	Out.ar(0, ((inputLevel * input) + (convLevel * PartConv.ar(input, a.fftsize, a.irspectrum.bufnum, 0.5))) ! 2);
}.play;
)

// convolve with target soundfile adding delayed input
(
{ var input, delayTime, inputDelay, inputLevel = 0.5, convLevel = 0.5;
	input = PlayBuf.ar(1, a.target, loop:1);
	delayTime =  BufFrames.ir(a.buffer.bufnum) / BufSampleRate.ir(a.buffer.bufnum);
	inputDelay = DelayC.ar(input * inputLevel, delayTime, delayTime);
	Out.ar(0, (inputDelay + (convLevel * PartConv.ar(input, a.fftsize, a.irspectrum.bufnum, 0.5))) ! 2);
}.play;
)


// convolve with live input
(
{ var input, convLevel = 0.8;
	input= SoundIn.ar(0);
	Out.ar(0, (convLevel * PartConv.ar(input, a.fftsize, a.irspectrum.bufnum)) ! 2);
}.play;
)

// convolve with live input adding input
(
{ var input, inputLevel = 0.7, convLevel = 0.7;
	input = SoundIn.ar(0);
	Out.ar(0, ((inputLevel * input) + (convLevel * PartConv.ar(input, a.fftsize, a.irspectrum.bufnum))) ! 2);
}.play;
)


// convolve with live input adding delayed input
(
{ var input, delayTime, delayedInput, inputLevel = 0.7, convLevel = 0.7;
	input = SoundIn.ar(0);
	delayTime =  BufFrames.ir(a.buffer.bufnum) / BufSampleRate.ir(a.buffer.bufnum);
	delayedInput = DelayC.ar(input, delayTime, delayTime);
	Out.ar(0, ((inputLevel * delayedInput) + (convLevel * PartConv.ar(input, a.fftsize, a.irspectrum.bufnum))) ! 2);
}.play;
)

//////////////////////////////////////////////////////


// save ir buffer to disk
(
a.savedBufferName = "/Users/paul/TESTING/TestSamples/_impulses/SavedImpulse_"   // e.g.
	++ Date.getDate.asSortableString
	++ ".aif";
a.buffer.write(a.savedBufferName,  headerFormat: "aiff", sampleFormat: "int24");
("Saved buffer to disk. filename: " ++ a.savedBufferName).postln;
)

//////////////////////////////////////////////////////


// free buffers when finished
(
if (a.notNil, {
	if (a.buffer.notNil, {
		a.buffer.free;
	});
	if (a.target.notNil, {
		a.target.free;
	});
	if (a.irspectrum.notNil, {
		a.irspectrum.free;
	});
});
)
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