diff src/Pitch.cpp @ 172:76b70af3a563

Merge from branch chroma-in-library

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Pitch.cpp	Thu Feb 05 09:53:06 2015 +0000
@@ -0,0 +1,63 @@
+/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
+/*
+    Constant-Q library
+    Copyright (c) 2013-2014 Queen Mary, University of London
+
+    Permission is hereby granted, free of charge, to any person
+    obtaining a copy of this software and associated documentation
+    files (the "Software"), to deal in the Software without
+    restriction, including without limitation the rights to use, copy,
+    modify, merge, publish, distribute, sublicense, and/or sell copies
+    of the Software, and to permit persons to whom the Software is
+    furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be
+    included in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+    CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+    Except as contained in this notice, the names of the Centre for
+    Digital Music; Queen Mary, University of London; and Chris Cannam
+    shall not be used in advertising or otherwise to promote the sale,
+    use or other dealings in this Software without prior written
+    authorization.
+*/
+
+#include "Pitch.h"
+
+#include <math.h>
+
+float
+Pitch::getFrequencyForPitch(int midiPitch,
+			    float centsOffset,
+			    float concertA)
+{
+    float p = float(midiPitch) + (centsOffset / 100);
+    return concertA * powf(2.0, (p - 69.0) / 12.0);
+}
+
+int
+Pitch::getPitchForFrequency(float frequency,
+			    float *centsOffsetReturn,
+			    float concertA)
+{
+    float p = 12.0 * (log(frequency / (concertA / 2.0)) / log(2.0)) + 57.0;
+
+    int midiPitch = int(p + 0.00001);
+    float centsOffset = (p - midiPitch) * 100.0;
+
+    if (centsOffset >= 50.0) {
+	midiPitch = midiPitch + 1;
+	centsOffset = -(100.0 - centsOffset);
+    }
+    
+    if (centsOffsetReturn) *centsOffsetReturn = centsOffset;
+    return midiPitch;
+}
+