From 8ed709d274357ede9c1b9e6a1e2d513dd5a4dcb6 Mon Sep 17 00:00:00 2001
From: Chris Cannam <cannam@all-day-breakfast.com>
Date: Tue, 7 Jun 2022 11:05:50 +0100
Subject: [PATCH] Don't run median filters for higher frequencies than we're
 going to use anyway

---
 src/finer/BinClassifier.h     |  4 +++-
 src/finer/BinSegmenter.h      | 17 +++++++----------
 src/finer/R3StretcherImpl.cpp | 14 +++++++++++---
 3 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/src/finer/BinClassifier.h b/src/finer/BinClassifier.h
index 105fcf8..94b1fa6 100644
--- a/src/finer/BinClassifier.h
+++ b/src/finer/BinClassifier.h
@@ -98,7 +98,9 @@ public:
         m_hFilters->reset();
     }
     
-    void classify(const double *const mag, Classification *classification) {
+    void classify(const double *const mag, // input, of at least binCount bins
+                  Classification *classification) // output, of binCount bins
+    {
         const int n = m_parameters.binCount;
 
         for (int i = 0; i < n; ++i) {
diff --git a/src/finer/BinSegmenter.h b/src/finer/BinSegmenter.h
index 20efb46..00fb1e4 100644
--- a/src/finer/BinSegmenter.h
+++ b/src/finer/BinSegmenter.h
@@ -45,21 +45,21 @@ public:
 
     struct Parameters {
         int fftSize;
+        int binCount;
         double sampleRate;
-        Parameters(int _fftSize, double _sampleRate) :
-            fftSize(_fftSize), sampleRate(_sampleRate) { }
+        Parameters(int _fftSize, int _binCount, double _sampleRate) :
+            fftSize(_fftSize), binCount(_binCount), sampleRate(_sampleRate) { }
     };
     
     BinSegmenter(Parameters parameters) :
         m_parameters(parameters),
-        m_binCount(m_parameters.fftSize/2 + 1),
-        m_numeric(m_binCount, 0),
-        m_classFilter(m_binCount / 64)
+        m_numeric(m_parameters.binCount, 0),
+        m_classFilter(16)
     {
     }
 
     Segmentation segment(const BinClassifier::Classification *classification) {
-        int n = m_binCount;
+        int n = m_parameters.binCount;
         for (int i = 0; i < n; ++i) {
             switch (classification[i]) {
             case BinClassifier::Classification::Harmonic:
@@ -79,12 +79,10 @@ public:
             }
         }
         double nyquist = m_parameters.sampleRate / 2.0;
-        int top = binForFrequency(16000.0);
-        if (top >= n) top = n-1;
         double f1 = nyquist;
         double f2 = nyquist;
         bool inPercussive = false;
-        for (int i = top; i > 0; --i) {
+        for (int i = n - 1; i > 0; --i) {
             if (m_numeric[i] == 1) { // percussive
                 if (!inPercussive) {
                     inPercussive = true;
@@ -103,7 +101,6 @@ public:
 
 protected:
     Parameters m_parameters;
-    int m_binCount;
     std::vector<int> m_numeric;
     MovingMedian<int> m_classFilter;
 
diff --git a/src/finer/R3StretcherImpl.cpp b/src/finer/R3StretcherImpl.cpp
index 0d42995..4849dbc 100644
--- a/src/finer/R3StretcherImpl.cpp
+++ b/src/finer/R3StretcherImpl.cpp
@@ -43,12 +43,20 @@ R3StretcherImpl::R3StretcherImpl(Parameters parameters,
     m_prevOuthop(1),
     m_draining(false)
 {
+    double maxClassifierFrequency = 16000.0;
+    if (maxClassifierFrequency > m_parameters.sampleRate/2) {
+        maxClassifierFrequency = m_parameters.sampleRate/2;
+    }
+    int classificationBins =
+        int(floor(m_guideConfiguration.classificationFftSize *
+                  maxClassifierFrequency / m_parameters.sampleRate));
+    
     BinSegmenter::Parameters segmenterParameters
         (m_guideConfiguration.classificationFftSize,
-         m_parameters.sampleRate);
+         classificationBins, m_parameters.sampleRate);
+    
     BinClassifier::Parameters classifierParameters
-        (m_guideConfiguration.classificationFftSize / 2 + 1,
-         9, 1, 10, 2.0, 2.0, 1.0e-7);
+        (classificationBins, 9, 1, 10, 2.0, 2.0, 1.0e-7);
 
     int inRingBufferSize = m_guideConfiguration.longestFftSize * 2;
     int outRingBufferSize = m_guideConfiguration.longestFftSize * 16;