diff base/Pitch.cpp @ 19:a7ed14263fe4

* Add Chromagram plugin, and make a number of fixes to the dense 3d model
  and colour 3d plot class to accommodate it
* Add pitch-conversion methods in base/Pitch
* Commit previously overlooked Command.cpp

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/base/Pitch.cpp	Wed Feb 01 14:49:49 2006 +0000
@@ -0,0 +1,79 @@
+/* -*- c-basic-offset: 4 -*-  vi:set ts=8 sts=4 sw=4: */
+
+/*
+    A waveform viewer and audio annotation editor.
+    Chris Cannam, Queen Mary University of London, 2005-2006
+    
+    This is experimental software.  Not for distribution.
+*/
+
+#include "Pitch.h"
+
+#include <cmath>
+
+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;
+}
+
+static QString notes[] = {
+    "C%1",  "C#%1", "D%1",  "D#%1",
+    "E%1",  "F%1",  "F#%1", "G%1",
+    "G#%1", "A%1",  "A#%1", "B%1"
+};
+
+QString
+Pitch::getPitchLabel(int midiPitch,
+		     float centsOffset)
+{
+    int octave = -2;
+
+    if (midiPitch < 0) {
+	while (midiPitch < 0) {
+	    midiPitch += 12;
+	    --octave;
+	}
+    } else {
+	octave = midiPitch / 12 - 2;
+    }
+
+    QString plain = notes[midiPitch % 12].arg(octave);
+
+    int ic = lrintf(centsOffset);
+    if (ic == 0) return plain;
+    else if (ic > 0) return QString("%1+%2c").arg(plain).arg(ic);
+    else return QString("%1%2c").arg(plain).arg(ic);
+}
+
+QString
+Pitch::getPitchLabelForFrequency(float frequency,
+				 float concertA)
+{
+    float centsOffset = 0.0;
+    int midiPitch = getPitchForFrequency(frequency, &centsOffset, concertA);
+    return getPitchLabel(midiPitch, centsOffset);
+}
+