pYin patch for detecting low frequencies

pyin-lf.patch

commit 6ed838b60173dc354fcb432e27bccb3a7a1e5769
Author: Xavier Riley <[email protected]>
Date:   Mon Jun 28 12:47:19 2021 +0100

    Reduce min frequency detectable from 61Hz to 22Hz

diff --git a/LocalCandidatePYIN.cpp b/LocalCandidatePYIN.cpp
index fc69308..4f04fbc 100644
--- a/LocalCandidatePYIN.cpp
+++ b/LocalCandidatePYIN.cpp
@@ -308,8 +308,8 @@ LocalCandidatePYIN::process(const float *const *inputBuffers, RealTime timestamp
 
     m_yinUtil->cumulativeDifference(yinBuffer);
     
-    float minFrequency = 60;
-    float maxFrequency = 900;
+    float minFrequency = 22;
+    float maxFrequency = 440;
     vector<double> peakProbability = m_yinUtil->yinProb(yinBuffer, 
                                                         m_threshDistr, 
                                                         m_inputSampleRate/maxFrequency, 
diff --git a/MonoNoteParameters.cpp b/MonoNoteParameters.cpp
index 8d9c950..7c5165e 100644
--- a/MonoNoteParameters.cpp
+++ b/MonoNoteParameters.cpp
@@ -14,7 +14,7 @@
 #include "MonoNoteParameters.h"
 
 MonoNoteParameters::MonoNoteParameters() :
-    minPitch(35), 
+    minPitch(21), 
     nPPS(3), 
     nS(69), 
     nSPP(3), // states per pitch
diff --git a/MonoPitchHMM.cpp b/MonoPitchHMM.cpp
index 82384f1..e162106 100644
--- a/MonoPitchHMM.cpp
+++ b/MonoPitchHMM.cpp
@@ -24,7 +24,7 @@ using std::pair;
 
 MonoPitchHMM::MonoPitchHMM(int fixedLag) :
     SparseHMM(fixedLag),
-    m_minFreq(61.735),
+    m_minFreq(27.500),
     m_nBPS(5),
     m_nPitch(0),
     m_transitionWidth(0),
diff --git a/PYinVamp.cpp b/PYinVamp.cpp
index a012e03..56958ac 100644
--- a/PYinVamp.cpp
+++ b/PYinVamp.cpp
@@ -32,8 +32,8 @@ PYinVamp::PYinVamp(float inputSampleRate) :
     m_channels(0),
     m_stepSize(256),
     m_blockSize(2048),
-    m_fmin(40),
-    m_fmax(1600),
+    m_fmin(22),
+    m_fmax(440),
     m_yin(2048, inputSampleRate, 0.0),
     m_oF0Candidates(0),
     m_oF0Probs(0),
diff --git a/Yin.cpp b/Yin.cpp
index d9e95c3..2c1e0dc 100644
--- a/Yin.cpp
+++ b/Yin.cpp
@@ -96,7 +96,13 @@ Yin::processProbabilisticYin(const double *in) const {
 
     m_yinUtil->cumulativeDifference(yinBuffer);
 
-    vector<double> peakProbability = m_yinUtil->yinProb(yinBuffer, m_threshDistr);
+    // vector<double> peakProbability = m_yinUtil->yinProb(yinBuffer, m_threshDistr);
+    float minFrequency = 22;
+    float maxFrequency = 440;
+    vector<double> peakProbability = m_yinUtil->yinProb(yinBuffer, 
+                                                        m_threshDistr, 
+                                                        m_inputSampleRate/maxFrequency, 
+                                                        m_inputSampleRate/minFrequency);
     
     // calculate overall "probability" from peak probability
     double probSum = 0;
diff --git a/YinUtil.cpp b/YinUtil.cpp
index 94b6ff1..1ea1e22 100644
--- a/YinUtil.cpp
+++ b/YinUtil.cpp
@@ -241,7 +241,7 @@ YinUtil::yinProb(const double *yinBuffer, int prior, int minTau0, int maxTau0)
     
     // double factor = 1.0 / (0.25 * (nThresholdInt+1) * (nThresholdInt + 1)); // factor to scale down triangular weight
     int minInd = 0;
-    float minVal = 42.f;
+    float minVal = 20.f;
     // while (currThreshInd != -1 && tau < maxTau)
     // {
     //     if (yinBuffer[tau] < thresholds[currThreshInd])