Comb: initial leg-work. See #54.

jamoma · Oct 21, 2015 · ad78419 · ad78419
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diff --git a/includes/Jamoma.h b/includes/Jamoma.h
@@ -131,6 +131,7 @@ constexpr inline uint32_t Hash(const char *const str, const uint32_t seed = 0xAE
 // Units
 
 #include "JamomaAllpass1.h"
+#include "JamomaComb.h"
 #include "JamomaDcblock.h"
 #include "JamomaGain.h"
 #include "JamomaLowpassOnePole.h"

diff --git a/includes/library/JamomaComb.h b/includes/library/JamomaComb.h
@@ -0,0 +1,166 @@
+/** @file
+	
+	@ingroup 	jamoma2
+	
+	@brief 		IIR comb filter
+	
+	@author		Timothy Place
+	@copyright	Copyright (c) 2005-2015 The Jamoma Group, http://jamoma.org.
+	@license	This project is released under the terms of the MIT License.
+ */
+
+#pragma once
+
+#include "JamomaAudioObject.h"
+#include "JamomaLowpassOnepole.h"
+
+namespace Jamoma {
+
+
+	/**	This AudioObject implements an IIR comb filter with an additional lowpass filter in the feedback loop.
+		The result is a comb filter that is warmer or "less tinny" than the typical comb filter.
+		This filter is one of the key building blocks in for the TapVerb effect.
+	 */
+	class Comb : public AudioObject {
+
+
+		const std::size_t			mCapacity;
+//		CircularSampleBufferGroup	mFeedforwardHistory;
+//		Delay			mFeedbackBuffer;
+		CircularSampleBufferGroup	mFeedbackHistory;
+		LowpassOnePole				mLowpassFilter;
+		Observer					mChannelCountObserver = { std::bind(&Comb::resizeHistory, this) };
+
+		void resizeHistory() {
+			if ((mFeedbackHistory.size() && mFeedbackHistory[0].size() != size+frameCount) || mFeedbackHistory.size() != (size_t)channelCount) {
+				mFeedbackHistory.clear(); // ugly: doing this to force the reconstruction of the storage to the correct size
+				mFeedbackHistory.resize(channelCount, std::make_pair(mCapacity+frameCount, (size_t)size+frameCount));
+			}
+		}
+
+
+	public:
+		static constexpr Classname classname = { "comb" };
+		static constexpr auto tags = { "dspFilterLib", "audio", "processor", "filter", "comb" };
+
+
+		/** TODO: Make capacity dynamic?  It already sort of is when the channel count changes...
+		 */
+		Comb(std::size_t capacity = 4410)
+		: mCapacity(capacity)
+		, mFeedbackHistory(1, capacity)
+		{
+			channelCount.addObserver(mChannelCountObserver);
+		}
+
+
+		/** size of the history buffers -- i.e. the delay time
+			TODO: dataspace integration for units other than samples
+		 */
+		Parameter<int>	size = { this, "size", 1,
+								[this]{
+									for (auto& channel : mFeedbackHistory)
+										channel.resize((int)size);
+								}
+		};
+
+
+		/** Delay time.
+			An alias of the #size parameter.
+			TODO: dataspace with Native Unit in samples
+		 */
+		Parameter<int>		delay = { this, "delay", 1, [this] { size = (int)delay; } };
+
+
+		/** Decay time -- is this really a dataspace conversion of the feedback coefficient?  maybe not...
+		 */
+		Parameter<double>	decay = { this, "decay", 0.0,
+			[this]{
+				//				mDeciResonance = resonance * 0.1;
+				//				calculateCoefficients();
+			}
+		};
+
+
+		/** Feedback coefficient.
+         */
+		Parameter<double>	feedback = { this, "feedback", 0.0,
+			[this]{
+//				mDeciResonance = resonance * 0.1;
+//				calculateCoefficients();
+			}
+		};
+
+
+		/** Clip the feedback internally to prevent the possibility of the filter blowing-up.
+		 */
+		Parameter<bool>		clip = {this, "clip", true, };
+
+
+		/** Cutoff Frequency for the internal lowpass filter
+		 */
+		Parameter<double>	cutoff = { this, "cutoff", 0.0,
+			[this]{
+				mLowpassFilter.frequency = (double)cutoff;
+				//				mDeciResonance = resonance * 0.1;
+				//				calculateCoefficients();
+			}
+		};
+
+
+
+		Message			setDelayIndependently = { "setDelayIndependently",
+													Synopsis("Set the delay parameter without recalculating decay times or other dependent parameters."),
+													[this]{
+														// TODO: implement
+														;
+													}
+		};
+
+
+		/**	This algorithm is an IIR filter, meaning that it relies on feedback.  If the filter should
+			not be producing any signal (such as turning audio off and then back on in a host) or if the
+			feedback has become corrupted (such as might happen if a NaN is fed in) then it may be
+			neccesary to clear the filter by calling this method.											
+		 */
+		Message			clear = { "clear",
+									Synopsis("Reset the Filter History"),
+									[this]{
+										mFeedbackHistory.clear();
+										mLowpassFilter.clear();
+									}
+		};
+
+
+
+
+
+		Sample operator()(Sample x)
+		{
+			return (*this)(x, 0);
+		}
+
+
+		Sample operator()(Sample x, int channel)
+		{
+            Sample y = x;
+
+			return y;
+		}
+
+
+		SharedSampleBundleGroup operator()(const SampleBundle& x)
+		{
+			auto out = adapt(x);
+
+			for (int channel=0; channel < x.channelCount(); ++channel) {
+				for	(int i=0; i < x.frameCount(); ++i)
+					out[0][channel][i] = (*this)(x[channel][i], channel);
+			}
+			return out;
+		}
+
+	};
+
+
+} // namespace Jamoma
diff --git a/tests/Comb/CMakeLists.txt b/tests/Comb/CMakeLists.txt
@@ -0,0 +1,8 @@
+cmake_minimum_required(VERSION 3.0)
+
+
+project(Comb)
+
+include(${PROJECT_SOURCE_DIR}/../UnitTest.cmake NO_POLICY_SCOPE)
+
+
diff --git a/tests/Comb/Comb.cpp b/tests/Comb/Comb.cpp
@@ -0,0 +1,123 @@
+/** @file
+	@ingroup 	jamoma2
+ 
+	@brief 		Unit test for the Comb class
+ 
+	@author		Timothy Place
+	@copyright	Copyright (c) 2005-2015 The Jamoma Group, http://jamoma.org.
+	@license	This project is released under the terms of the MIT License.
+
+ */
+
+#include "Jamoma.h"
+
+
+class CombTest {
+
+	Jamoma::UnitTest<CombTest>*	mTest;
+
+public:
+	CombTest(Jamoma::UnitTest<CombTest>* test)
+	: mTest(test)
+	{
+		testImpulseResponse();
+	}
+
+
+	void testImpulseResponse()
+	{
+		Jamoma::Comb my_comb;
+
+		my_comb.sampleRate = 44100;
+		my_comb.delay = 22;			// 22 samples == 0.5 ms @ f_s = 44100
+		my_comb.feedback = 0.9;		//
+		my_comb.cutoff = 1.0;		// normalized freq (no lowpass)
+
+		Jamoma::UnitImpulse impulse;
+
+		impulse.channelCount = 1;
+		impulse.frameCount = 64;
+
+		auto out_samples = my_comb( impulse() );
+
+
+		// coefficients calculated in Max using the "Comb" tab of the filterdetail object help patcher:
+		//	a = [1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0];	% numerator (fir)
+		//	b = [1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, -0.9];	% denominator (iir)
+		//	i = impz(a, b, 64);
+
+
+		// Max's filterdetail produces:
+		Jamoma::SampleVector expectedIR = {
+			1.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.9, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.81, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			 0.729, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.6561, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.59049, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.531441, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.478297, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.430467, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.38742, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.348678, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.313811, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.28243, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.254187, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.228768, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.205891, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.185302, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.166772, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.150095, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.135085, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.121577, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.109419, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.098477, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0  ,
+			0.088629, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0
+		};
+
+		int badSampleCount = 0;
+		Jamoma::Sample temp = 0.0;
+		Jamoma::Sample tempExpected = 0.0;
+
+		for (int i = 0; i < expectedIR.size(); i++) {
+			temp = out_samples[0][0][i];
+			tempExpected = expectedIR[i];
+			if (! mTest->compare(temp, tempExpected) ) {
+				badSampleCount++;
+				std::cout << "sample " << i << " had a difference of " << std::fabs(temp - tempExpected) << std::endl;
+			}
+		}
+
+		std::cout << "the impulse response of my_comb has " << badSampleCount << " bad samples" << std::endl;
+		mTest->TEST_ASSERT("Bad Sample Count", badSampleCount == 0);
+
+
+
+		// Test range limiting
+//		my_lowpass.frequency = 100.0;
+//		mTest->TEST_ASSERT("frequency setting is correct", my_lowpass.frequency == 100.0);
+//		
+//		my_lowpass.frequency = 5.0;
+//		mTest->TEST_ASSERT("low frequency is clipped", my_lowpass.frequency == 20.0);
+//		
+//		// TODO: boundaries for this object need to change when the sampleRate changes -- currently they don't!
+//		// So we do this test with the initial sampleRate instead of with `my_lowpass.sampleRate`
+//		my_lowpass.frequency = 100000;
+//		mTest->TEST_ASSERT("high frequency is clipped", my_lowpass.frequency < 96000 * 0.5);
+//		
+//		// resonance is not clipped at the moment, so we can do irrational bad things...  we should change this
+//		my_lowpass.resonance = 100.0;
+//		mTest->TEST_ASSERT("insane resonance is not clipped", my_lowpass.resonance == 100.0);
+//		
+//		my_lowpass.resonance = -5.0;
+//		mTest->TEST_ASSERT("negative resonance is not clipped", my_lowpass.resonance == -5.0);
+	}
+
+};
+
+
+int main(int argc, const char * argv[])
+{
+	Jamoma::UnitTest<CombTest>	aUnitTestInstance;
+	return aUnitTestInstance.failureCount();
+}