BogaudioModules

commit d571753e6242b7bffa220f9c5f825ae02d51c056
parent 47dcfa8baf66c54ba0b6302e13bfcfb9d669e160
Author: Matt Demanett <matt@demanett.net>
Date:   Wed,  7 Oct 2020 00:12:18 -0400

ADSR, others: fix decay and release stage shapes very slightly, for a cleaner / less abrupt onset of the stage, avoiding a pop when driving a VCA in some situations.

Diffstat:
M
src/Test2.cpp
 | 
2
+-
M
src/dsp/envelope.cpp
 | 
15
++++++++-------
M
src/dsp/envelope.hpp
 | 
9
++++-----
M
src/dsp/signal.hpp
 | 
1
+

4 files changed, 14 insertions(+), 13 deletions(-)
diff --git a/src/Test2.cpp b/src/Test2.cpp
@@ -82,7 +82,7 @@ void Test2::processChannel(const ProcessArgs& args, int _c) {
 			decayShape *= 2.0f;
 			decayShape += 1.0f;
 		}
-		_adsr.setShapes(attackShape, decayShape, decayShape);
+		_adsr.setShapes(attackShape, 1.0f / decayShape, 1.0f / decayShape); // FIXME: inversions here untested
 		outputs[OUT_OUTPUT].setVoltage(_adsr.next() * 10.0f);
 	}
 
diff --git a/src/dsp/envelope.cpp b/src/dsp/envelope.cpp
@@ -8,13 +8,15 @@
 using namespace bogaudio::dsp;
 
 void EnvelopeGenerator::setSampleRate(float sampleRate) {
-	if (_sampleRate != sampleRate && sampleRate >= 1.0) {
+	assert(sampleRate >= 1.0f);
+	if (_sampleRate != sampleRate) {
 		_sampleRate = sampleRate;
 		_sampleTime = 1.0f / sampleRate;
 		_sampleRateChanged();
 	}
 }
 
+
 void ADSR::reset() {
 	_stage = STOPPED_STAGE;
 	_gated = false;
@@ -51,7 +53,7 @@ void ADSR::setLinearShape(bool linear) {
 		setShapes(1.0f, 1.0f, 1.0f);
 	}
 	else {
-		setShapes(0.5f, 0.5f, 0.5f);
+		setShapes(0.5f, 2.0f, 2.0f);
 	}
 }
 
@@ -106,7 +108,7 @@ float ADSR::_next() {
 			}
 			case RELEASE_STAGE: {
 				_stage = ATTACK_STAGE;
-				_stageProgress = _attack * powf(_envelope, 1.0f / _releaseShape);
+				_stageProgress = _attack * powf(_envelope, _releaseShape);
 				break;
 			}
 		}
@@ -147,9 +149,9 @@ float ADSR::_next() {
 		case DECAY_STAGE: {
 			_stageProgress += _sampleTime;
 			_envelope = std::min(1.0f, _stageProgress / _decay);
-			_envelope = powf(_envelope, _decayShape);
+			_envelope = powf(1.0f - _envelope, _decayShape);
 			_envelope *= 1.0f - _sustain;
-			_envelope = 1.0f - _envelope;
+			_envelope += _sustain;
 			break;
 		}
 		case SUSTAIN_STAGE: {
@@ -159,9 +161,8 @@ float ADSR::_next() {
 		case RELEASE_STAGE: {
 			_stageProgress += _sampleTime;
 			_envelope = std::min(1.0f, _stageProgress / _release);
-			_envelope = powf(_envelope, _releaseShape);
+			_envelope = powf(1.0f - _envelope, _releaseShape);
 			_envelope *= _releaseLevel;
-			_envelope = _releaseLevel - _envelope;
 			break;
 		}
 	}
diff --git a/src/dsp/envelope.hpp b/src/dsp/envelope.hpp
@@ -3,18 +3,17 @@
 #include <stdlib.h>
 
 #include "base.hpp"
+#include "signal.hpp"
 
 namespace bogaudio {
 namespace dsp {
 
 struct EnvelopeGenerator : Generator {
-	float _sampleRate;
+	float _sampleRate = -1.0f;
 	float _sampleTime;
 
-	EnvelopeGenerator(float sampleRate = 1000.0f)
-	: _sampleRate(sampleRate > 1.0 ? sampleRate : 1.0)
-	, _sampleTime(1.0f / _sampleRate)
-	{
+	EnvelopeGenerator(float sampleRate = 1000.0f) {
+		setSampleRate(std::max(1.0f, sampleRate));
 	}
 
 	void setSampleRate(float sampleRate);
diff --git a/src/dsp/signal.hpp b/src/dsp/signal.hpp
@@ -106,6 +106,7 @@ struct SlewLimiter {
 	}
 
 	void setParams(float sampleRate = 1000.0f, float milliseconds = 1.0f, float range = 10.0f);
+	inline void setLast(float last) { _last = last; }
 	inline float next(float sample) {
 		return _last = next(sample, _last);
 	}