BogaudioModules

commit 45368d486bac5cdf16ff3b1147cac0633373e6ad
parent 62a0883bd4946d4056e15eadb8892f996ddd4024
Author: Matt Demanett <matt@demanett.net>
Date:   Mon,  6 May 2019 22:45:21 -0400

Fix jump() in dsp RandomWalk.

Diffstat:
M
src/dsp/noise.cpp
 | 
10
++++++----
M
src/dsp/noise.hpp
 | 
1
+

2 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/src/dsp/noise.cpp b/src/dsp/noise.cpp
@@ -34,20 +34,22 @@ void RandomWalk::setParams(float sampleRate, float change) {
 
 	const float maxDamp = 0.98;
 	const float minDamp = 0.9999;
-	_damp = maxDamp + (1 - change)*(minDamp - maxDamp);
+	_damp = maxDamp + (1.0f - change)*(minDamp - maxDamp);
+
+	_biasDamp = 1.0f - change*(2.0f / sampleRate);
 }
 
 void RandomWalk::jump() {
-	// FIXME
-	_bias = _noise.next() * 5.0f;
+	_last = _bias = _noise.next() * 5.0f;
 	_filter.reset();
 }
 
 float RandomWalk::_next() {
 	float delta = _noise.next();
-	if ((_lastOut >= _max - _bias && delta > 0.0f) || (_lastOut <= _min - _bias && delta < 0.0f)) {
+	if ((_lastOut >= _max && delta > 0.0f) || (_lastOut <= _min && delta < 0.0f)) {
 		delta = -delta;
 	}
 	_last = _damp*_last + delta;
+	_bias *= _biasDamp;
 	return _lastOut = std::min(std::max(_bias + _filter.next(_last), _min), _max);
 }
diff --git a/src/dsp/noise.hpp b/src/dsp/noise.hpp
@@ -93,6 +93,7 @@ struct RandomWalk : Generator {
 	float _lastOut = 0.0f;
 	float _damp;
 	float _bias = 0.0f;
+	float _biasDamp = 1.0f;
 	WhiteNoiseGenerator _noise;
 	LowPassFilter _filter;