From 84cd061e9d3c8ed5db955433c157739082d5cf3d Mon Sep 17 00:00:00 2001
From: Chris Cannam <cannam@all-day-breakfast.com>
Date: Thu, 26 May 2022 17:46:13 +0100
Subject: [PATCH] Avoid duplicate bin in the different scales

---
 src/finer/R3StretcherImpl.cpp | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/finer/R3StretcherImpl.cpp b/src/finer/R3StretcherImpl.cpp
index 9c4236e..4521f33 100644
--- a/src/finer/R3StretcherImpl.cpp
+++ b/src/finer/R3StretcherImpl.cpp
@@ -597,12 +597,13 @@ R3StretcherImpl::synthesiseChannel(int c, int outhop)
         // The frequency filter is applied naively in the frequency
         // domain. Aliasing is reduced by the shorter resynthesis
         // window
-                
-        double factor = m_parameters.sampleRate / double(fftSize);
+
+        int lowBin = int(floor(fftSize * band.f0 / m_parameters.sampleRate));
+        int highBin = int(floor(fftSize * band.f1 / m_parameters.sampleRate));
+        if (highBin % 2 == 1) --highBin;
+        
         for (int i = 0; i < fftSize/2 + 1; ++i) {
-            double f = double(i) * factor;
-            if (f >= band.f0 && f < band.f1) {
-                //!!! check the mod 2 bit from stretch-fn
+            if (i >= lowBin && i < highBin) {
                 scale->mag[i] *= winscale;
             } else {
                 scale->mag[i] = 0.f;