sam/sfizz
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Oversample the limiter by 2x

Browse source
This commit is contained in:
Jean Pierre Cimalando 2020-03-29 20:17:49 +02:00
parent 3ab8eb8ad4
commit 03b9e19676
4 changed files with 31 additions and 6 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

25
src/sfizz/effects/Limiter.cpp
View file

@ -12,9 +12,12 @@
#include "Limiter.h"
#include "Opcode.h"
#include "gen/limiter.cpp"
#include "AudioSpan.h"
#include "absl/memory/memory.h"
static constexpr int _oversampling = 2;
#include "gen/limiter.cpp"
namespace sfz {
namespace fx {
@ -32,12 +35,20 @@ namespace fx {
{
_limiter->classInit(sampleRate);
_limiter->instanceConstants(sampleRate);
static constexpr double coefs2x[12] = { 0.036681502163648017, 0.13654762463195794, 0.27463175937945444, 0.42313861743656711, 0.56109869787919531, 0.67754004997416184, 0.76974183386322703, 0.83988962484963892, 0.89226081800387902, 0.9315419599631839, 0.96209454837808417, 0.98781637073289585 };
for (unsigned c = 0; c < EffectChannels; ++c) {
_downsampler2x[c].set_coefs(coefs2x);
_upsampler2x[c].set_coefs(coefs2x);
}
clear();
}
void Limiter::setSamplesPerBlock(int samplesPerBlock)
{
(void)samplesPerBlock;
_tempBuffer2x.resize(2 * samplesPerBlock);
}
void Limiter::clear()
@ -47,7 +58,15 @@ namespace fx {
void Limiter::process(const float* const inputs[], float* const outputs[], unsigned nframes)
{
_limiter->compute(nframes, inputs, outputs);
auto inOut2x = AudioSpan<float>( _tempBuffer2x).first(2 * nframes);
for (unsigned c = 0; c < EffectChannels; ++c)
_upsampler2x[c].process_block(inOut2x.getSpan(c).data(), inputs[c], nframes);
_limiter->compute(2 * nframes, inOut2x, inOut2x);
for (unsigned c = 0; c < EffectChannels; ++c)
_downsampler2x[c].process_block(outputs[c], inOut2x.getSpan(c).data(), nframes);
}
std::unique_ptr<Effect> Limiter::makeInstance(absl::Span<const Opcode> members)

5
src/sfizz/effects/Limiter.h
View file

@ -6,6 +6,8 @@
#pragma once
#include "Effects.h"
#include "hiir/Downsampler2xFpu.h"
#include "hiir/Upsampler2xFpu.h"
class faustLimiter;
namespace sfz {
@ -47,6 +49,9 @@ namespace fx {
private:
std::unique_ptr<faustLimiter> _limiter;
AudioBuffer<float, 2> _tempBuffer2x { 2, 2 * config::defaultSamplesPerBlock };
hiir::Downsampler2xFpu<12> _downsampler2x[EffectChannels];
hiir::Upsampler2xFpu<12> _upsampler2x[EffectChannels];
};
} // namespace fx

5
src/sfizz/effects/dsp/limiter.dsp
View file

@ -1,8 +1,9 @@
import("stdfaust.lib");
limiter(x) = gain*x with {
att = 0.0008;
rel = 0.5;
att = 0.0008 * over;
rel = 0.5 * over;
over = fconstant(int _oversampling, <math.h>);
peak = x : an.amp_follower_ud(att, rel);
gain = ba.if(peak>1.0, 1.0/peak, 1.0) : si.smooth(ba.tau2pole(0.5*att));
};

2
src/sfizz/effects/gen/limiter.cpp
View file

@ -51,7 +51,7 @@ public:
void instanceConstants(int sample_rate)
{
fSampleRate = sample_rate;
fConst0 = std::min<float>(192000.0f, std::max<float>(1.0f, float(fSampleRate)));
fConst0 = (std::min<float>(192000.0f, std::max<float>(1.0f, float(fSampleRate))) * float(_oversampling));
fConst1 = std::exp((0.0f - (2500.0f / fConst0)));
fConst2 = (1.0f - fConst1);
fConst3 = std::exp((0.0f - (1250.0f / fConst0)));