commit b5521a1a509d51199602ccbcc2d9db6a6bd359a7
parent 405f4d07a296924fdd89c809dba6ce1c6bc268b4
Author: Matt Demanett <matt@demanett.net>
Date: Sun, 23 Aug 2020 09:17:15 -0400
(L)VCF: avoid filter blowup when cutoff is zero at high sampling rates.
Diffstat:
4 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/src/LVCF.cpp b/src/LVCF.cpp
@@ -15,6 +15,7 @@ void LVCF::Engine::setParams(
MultimodeFilter::BandwidthMode bwm
) {
frequency = semitoneToFrequency(_frequencySL.next(frequencyToSemitone(frequency)));
+ frequency = clamp(semitoneToFrequency(_frequencySL.next(frequencyToSemitone(frequency))), LVCF::minFrequency, LVCF::maxFrequency);
_filter.setParams(
_sampleRate,
diff --git a/src/VCF.cpp b/src/VCF.cpp
@@ -13,7 +13,7 @@ void VCF::Engine::setParams(
float qbw,
MultimodeFilter::BandwidthMode bwm
) {
- frequency = semitoneToFrequency(_frequencySL.next(frequencyToSemitone(frequency)));
+ frequency = clamp(semitoneToFrequency(_frequencySL.next(frequencyToSemitone(frequency))), VCF::minFrequency, VCF::maxFrequency);
int i = -1, j = -1;
std::fill(_gains, _gains + nFilters, 0.0f);
diff --git a/src/dsp/filters/multimode.cpp b/src/dsp/filters/multimode.cpp
@@ -178,6 +178,10 @@ constexpr float MultimodeTypes::minBWPitch;
constexpr float MultimodeTypes::maxBWPitch;
+template<int N> float MultimodeDesigner<N>::effectiveMinimumFrequency() {
+ return minFrequency * std::max(1.0f, roundf(_sampleRate / 44100.0f));
+}
+
template<int N> void MultimodeDesigner<N>::setParams(
BiquadBank<T, N>& biquads,
float& outGain,
@@ -194,6 +198,7 @@ template<int N> void MultimodeDesigner<N>::setParams(
assert(poles >= minPoles && (poles <= N || (poles <= 2*N && (mode == LOWPASS_MODE || mode == HIGHPASS_MODE))));
assert(poles % modPoles == 0);
assert(frequency >= minFrequency - 0.00001f && frequency <= maxFrequency);
+ frequency = std::max(frequency, effectiveMinimumFrequency());
assert(qbw >= minQbw && qbw <= maxQbw);
bool repole = _type != type || _mode != mode || _nPoles != poles || (type == CHEBYSHEV_TYPE && (mode == LOWPASS_MODE || mode == HIGHPASS_MODE) && _qbw != qbw);
diff --git a/src/dsp/filters/multimode.hpp b/src/dsp/filters/multimode.hpp
@@ -124,6 +124,7 @@ struct MultimodeDesigner : MultimodeTypes {
Pole _poles[maxPoles / 2];
int _nBiquads = 0;
+ float effectiveMinimumFrequency();
void setParams(
BiquadBank<T, N>& biquads,
float& outGain,
@@ -157,6 +158,7 @@ struct MultimodeBase : MultimodeFilter {
BiquadBank<T, N> _biquads;
float _outGain = 1.0f;
+ inline float effectiveMinimumFrequency() { return _designer.effectiveMinimumFrequency(); }
void setParams(
float sampleRate,
Type type,
