GuitarML sample rate correction filter (#267)

* GuitarML: Adding optional sample rate correction filter

* Try to fix file chooser bug on Linux

* Adjust makeup filter tuning

* Apply clang-format

* Fix ambiguous chowdsp::Version

---------

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

CMakeLists.txt

@@ -3,7 +3,7 @@ set(CMAKE_OSX_DEPLOYMENT_TARGET "10.12" CACHE STRING "Minimum OS X deployment ta
 if(WIN32)
     set(CMAKE_SYSTEM_VERSION 7.1 CACHE STRING INTERNAL FORCE) # Windows SDK for Windows 7 and up
 endif()
-project(BYOD VERSION 1.1.3)
+project(BYOD VERSION 1.1.4)
 
 if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
     set(CMAKE_CXX_STANDARD 17)

sim/GuitarML/filter_design.py

@@ -0,0 +1,39 @@
+import numpy as np
+from scipy.io import wavfile
+import scipy.signal as signal
+import matplotlib.pyplot as plt
+import audio_dspy as adsp
+
+def freqSmooth(x, sm=1.0/24.0):
+    s = sm if sm > 1.0 else np.sqrt(2.0**sm)
+    N = len(x)
+    y = np.zeros_like(x)
+    for i in range(N):
+        i1 = max(int(np.floor(i/s)), 0)
+        i2 = min(int(np.floor(i*s)+1), N-1)
+        if i2 > i1:
+            y[i] = np.mean(x[i1:i2])
+    return y
+
+def plot_fft(sig, fs, gain=1):
+    b,a = adsp.design_highshelf(1000, 0.7071, gain, fs)
+    xx = signal.lfilter(b, a, sig)
+
+    freqs = np.fft.rfftfreq(len(xx), 1.0 / fs)
+    fft = freqSmooth(np.fft.rfft(xx), 1.0)
+    plt.semilogx(freqs, 20 * np.log10(np.abs(fft)))
+
+fs, x = wavfile.read("noise_48k.wav")
+print(fs)
+plot_fft(x, fs)
+
+fs, x = wavfile.read("noise_96k.wav")
+print(fs)
+plot_fft(x, fs) #, 1 / 2)
+
+fs, x = wavfile.read("noise_192k.wav")
+print(fs)
+plot_fft(x, fs) #, 1 / 4)
+
+plt.xlim(20, 28000)
+plt.show()

src/headless/CMakeLists.txt

@@ -14,6 +14,7 @@ target_sources(BYOD_headless PRIVATE
     PresetResaver.cpp
     PresetSaveLoadTime.cpp
     ScreenshotGenerator.cpp
+    GuitarMLFilterDesigner.cpp
 
     tests/ParameterSmoothTest.cpp
     tests/PreBufferTest.cpp

src/headless/GuitarMLFilterDesigner.cpp

@@ -0,0 +1,54 @@
+#include "GuitarMLFilterDesigner.h"
+#include "../BYOD.h"
+
+GuitarMLFilterDesigner::GuitarMLFilterDesigner()
+{
+    this->commandOption = "--guitarml-filter";
+    this->argumentDescription = "--guitarml-filter";
+    this->shortDescription = "Generates files for GuitarML filter design";
+    this->longDescription = "";
+    this->command = [=] (const ArgumentList& args)
+    { generateFiles (args); };
+}
+
+void GuitarMLFilterDesigner::generateFiles ([[maybe_unused]] const ArgumentList& args)
+{
+    static constexpr int bufferSize = 8192;
+    chowdsp::AudioFileSaveLoadHelper saveLoadHelper;
+
+    chowdsp::Noise<float> noiseGenerator;
+    noiseGenerator.setGainDecibels (0.0f);
+    noiseGenerator.setSeed (123);
+    noiseGenerator.setNoiseType (chowdsp::Noise<float>::NoiseType::Normal);
+
+    const auto factory = ProcessorStore::getStoreMap().at ("GuitarML");
+    const auto processFile = [&factory,
+                              &saveLoadHelper,
+                              &noiseGenerator] (const juce::String& filePath, double sampleRate)
+    {
+        const auto file = File { filePath };
+        std::cout << "Rendering file " << file.getFullPathName() << " at sample rate " << sampleRate << std::endl;
+
+        noiseGenerator.prepare ({ sampleRate, (uint32_t) bufferSize, 1 });
+
+        auto processor = factory (nullptr);
+        processor->getParameters()[3]->setValueNotifyingHost (1.0f);
+        processor->prepareProcessing (sampleRate, bufferSize);
+
+        AudioBuffer<float> buffer { 1, bufferSize };
+        buffer.clear();
+        auto&& block = dsp::AudioBlock<float> { buffer };
+
+        noiseGenerator.process (dsp::ProcessContextReplacing<float> { block });
+        buffer.clear();
+        noiseGenerator.process (dsp::ProcessContextReplacing<float> { block });
+        processor->processAudioBlock (buffer);
+
+        file.deleteFile();
+        saveLoadHelper.saveBufferToFile (filePath, buffer, sampleRate);
+    };
+
+    processFile ("noise_48k.wav", 48000.0);
+    processFile ("noise_96k.wav", 96000.0);
+    processFile ("noise_192k.wav", 192000.0);
+}

src/headless/GuitarMLFilterDesigner.h

@@ -0,0 +1,15 @@
+#pragma once
+
+#include "../pch.h"
+
+class GuitarMLFilterDesigner : public ConsoleApplication::Command
+{
+public:
+    GuitarMLFilterDesigner();
+
+private:
+    /** Generates files for plotting GuitarML frequency content */
+    static void generateFiles (const ArgumentList& args);
+
+    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (GuitarMLFilterDesigner)
+};

src/headless/main.cpp

@@ -1,3 +1,4 @@
+#include "GuitarMLFilterDesigner.h"
 #include "PresetResaver.h"
 #include "PresetSaveLoadTime.h"
 #include "ScreenshotGenerator.h"
@@ -29,6 +30,7 @@ int main (int argc, char* argv[])
     app.addCommand (ScreenshotGenerator());
     app.addCommand (PresetResaver());
     app.addCommand (PresetSaveLoadTime());
+    app.addCommand (GuitarMLFilterDesigner());
     app.addCommand (UnitTests());
 
     // ArgumentList args { "--unit-tests", "--all" };

src/processors/drive/GuitarMLAmp.cpp

@@ -21,6 +21,7 @@ const auto numBuiltInModels = (int) guitarMLModelResources.size();
 const String modelTag = "model";
 const String gainTag = "gain";
 const String conditionTag = "condition";
+const String sampleRateCorrFilterTag = "sample_rate_corr_filter";
 const String customModelTag = "custom_model";
 constexpr std::string_view modelNameTag = "byod_guitarml_model_name";
 
@@ -46,6 +47,8 @@ GuitarMLAmp::GuitarMLAmp (UndoManager* um) : BaseProcessor ("GuitarML", createPa
     using namespace ParameterHelpers;
     loadParameterPointer (gainParam, vts, gainTag);
     conditionParam.setParameterHandle (getParameterPointer<chowdsp::FloatParameter*> (vts, conditionTag));
+    loadParameterPointer (sampleRateCorrectionFilterParam, vts, sampleRateCorrFilterTag);
+    addPopupMenuParameter (sampleRateCorrFilterTag);
 
     loadModel (0); // load Blues Jr. model by default
 
@@ -65,6 +68,7 @@ ParamLayout GuitarMLAmp::createParameterLayout()
 
     createGainDBParameter (params, gainTag, "Gain", -18.0f, 18.0f, 0.0f);
     createPercentParameter (params, conditionTag, "Condition", 0.5f);
+    emplace_param<chowdsp::BoolParameter> (params, sampleRateCorrFilterTag, "Sample Rate Correction Filter", true);
 
     return { params.begin(), params.end() };
 }
@@ -101,6 +105,12 @@ void GuitarMLAmp::loadModelFromJson (const chowdsp::json& modelJson, const Strin
     const auto modelSampleRate = modelDataJson.value ("sample_rate", 44100.0);
     const auto rnnDelaySamples = jmax (1.0, processSampleRate / modelSampleRate);
 
+    sampleRateCorrectionFilter.reset();
+    sampleRateCorrectionFilter.calcCoefs (8100.0f,
+                                          chowdsp::CoefficientCalculators::butterworthQ<float>,
+                                          (processSampleRate < modelSampleRate * 1.1) ? 1.0f : 0.25f,
+                                          (float) processSampleRate);
+
     if (numInputs == 1 && hiddenSize == 40) // non-conditioned LSMT40
     {
         SpinLock::ScopedLockType modelChangingLock { modelChangingMutex };
@@ -220,6 +230,8 @@ void GuitarMLAmp::prepare (double sampleRate, int samplesPerBlock)
     inGain.prepare (spec);
     inGain.setRampDurationSeconds (0.1);
 
+    sampleRateCorrectionFilter.prepare (2);
+
     conditionParam.prepare (sampleRate, samplesPerBlock);
     conditionParam.setRampLength (0.05);
 
@@ -279,6 +291,11 @@ void GuitarMLAmp::processAudio (AudioBuffer<float>& buffer)
         }
     }
 
+    if (sampleRateCorrectionFilterParam->get())
+    {
+        sampleRateCorrectionFilter.processBlock (buffer);
+    }
+
     buffer.applyGain (normalizationGain);
 
     dcBlocker.processAudio (buffer);
@@ -306,6 +323,13 @@ void GuitarMLAmp::fromXML (XmlElement* xml, const chowdsp::Version& version, boo
     }
 
     BaseProcessor::fromXML (xml, version, loadPosition);
+
+    using namespace std::string_view_literals;
+    if (version < chowdsp::Version { "1.1.4"sv })
+    {
+        // Sample rate correction filters were only added in version 1.1.4
+        sampleRateCorrectionFilterParam->setValueNotifyingHost (0.0f);
+    }
 }
 
 bool GuitarMLAmp::getCustomComponents (OwnedArray<Component>& customComps, chowdsp::HostContextProvider& hcp)
@@ -404,7 +428,7 @@ bool GuitarMLAmp::getCustomComponents (OwnedArray<Component>& customComps, chowd
 
             onChange = [this, &processor]
             {
-                processor.loadModel (getSelectedItemIndex(), getParentComponent());
+                processor.loadModel (getSelectedItemIndex(), getTopLevelComponent());
             };
 
             this->setName (modelTag + "__box");
@@ -429,6 +453,7 @@ bool GuitarMLAmp::getCustomComponents (OwnedArray<Component>& customComps, chowd
 
 void GuitarMLAmp::addToPopupMenu (PopupMenu& menu)
 {
+    BaseProcessor::addToPopupMenu (menu);
     menu.addItem ("Download more models", []
                   { URL { "https://guitarml.com/tonelibrary/tonelib-pro.html" }.launchInDefaultBrowser(); });
     menu.addSeparator();

src/processors/drive/GuitarMLAmp.h

@@ -32,6 +32,7 @@ class GuitarMLAmp : public BaseProcessor
 
     chowdsp::FloatParameter* gainParam = nullptr;
     chowdsp::SmoothedBufferValue<float> conditionParam;
+    chowdsp::BoolParameter* sampleRateCorrectionFilterParam = nullptr;
     chowdsp::Gain<float> inGain;
 
     SpinLock modelChangingMutex;
@@ -46,6 +47,7 @@ class GuitarMLAmp : public BaseProcessor
 
     std::array<LSTM40Cond, 2> lstm40CondModels;
     std::array<LSTM40NoCond, 2> lstm40NoCondModels;
+    chowdsp::HighShelfFilter<float> sampleRateCorrectionFilter;
 
     enum class ModelArch
     {

src/processors/tone/AmpIRs.cpp

@@ -292,7 +292,7 @@ bool AmpIRs::getCustomComponents (OwnedArray<Component>& customComps, chowdsp::H
                     fileItem.isTicked = file == ampIRs.curFile;
                     fileItem.action = [this, file]
                     {
-                        ampIRs.loadIRFromStream (file.createInputStream(), getParentComponent());
+                        ampIRs.loadIRFromStream (file.createInputStream(), getTopLevelComponent());
                     };
                     menu->addItem (fileItem);