view base/Pitch.h @ 335:02d2ad95ea52 spectrogram-cache-rejig

* Get storage advice for each cache in an FFT data server.  Allows us to be
  more confident about the actual memory situation and cut over from memory
  to disc part way through an FFT calculation if necessary.  StorageAdviser
  is now a bit too optimistic though (it's too keen to allocate large numbers
  of small blocks in memory).

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    Sonic Visualiser
    An audio file viewer and annotation editor.
    Centre for Digital Music, Queen Mary, University of London.
    This file copyright 2006 Chris Cannam.
    
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#ifndef _PITCH_H_
#define _PITCH_H_

#include <QString>

class Pitch
{
public:
    /**
     * Return the frequency at the given MIDI pitch plus centsOffset
     * cents (1/100ths of a semitone).  centsOffset does not have to
     * be in any particular range or sign.
     *
     * If concertA is non-zero, use that as the reference frequency
     * for the A at MIDI pitch 69; otherwise use the tuning frequency
     * specified in the application preferences (default 440Hz).
     */
    static float getFrequencyForPitch(int midiPitch,
				      float centsOffset = 0,
				      float concertA = 0.0);

    /**
     * Return the nearest MIDI pitch to the given frequency.
     *
     * If centsOffsetReturn is non-NULL, return in *centsOffsetReturn
     * the number of cents (1/100ths of a semitone) difference between
     * the given frequency and that of the returned MIDI pitch.  The
     * cents offset will be in the range [-50,50).
     * 
     * If concertA is non-zero, use that as the reference frequency
     * for the A at MIDI pitch 69; otherwise use the tuning frequency
     * specified in the application preferences (default 440Hz).
     */
    static int getPitchForFrequency(float frequency,
				    float *centsOffsetReturn = 0,
				    float concertA = 0.0);

    /**
     * Return a string describing the given MIDI pitch, with optional
     * cents offset.  This consists of the note name, octave number
     * (with MIDI pitch 0 having octave number -2), and optional
     * cents.
     *
     * For example, "A#3" (A# in octave 3) or "C2-12c" (C in octave 2,
     * minus 12 cents).
     *
     * If useFlats is true, spell notes with flats instead of sharps,
     * e.g. Bb3 instead of A#3.
     */
    static QString getPitchLabel(int midiPitch,
				 float centsOffset = 0,
				 bool useFlats = false);

    /**
     * Return a string describing the nearest MIDI pitch to the given
     * frequency, with cents offset.
     *
     * If concertA is non-zero, use that as the reference frequency
     * for the A at MIDI pitch 69; otherwise use the tuning frequency
     * specified in the application preferences (default 440Hz).
     *
     * If useFlats is true, spell notes with flats instead of sharps,
     * e.g. Bb3 instead of A#3.
     */
    static QString getPitchLabelForFrequency(float frequency,
					     float concertA = 0.0,
					     bool useFlats = false);

    /**
     * Return true if the given frequency falls within the range of
     * MIDI note pitches, plus or minus half a semitone.  This is
     * equivalent to testing whether getPitchForFrequency returns a
     * pitch in the MIDI range (0 to 127 inclusive) with any cents
     * offset.
     *
     * If concertA is non-zero, use that as the reference frequency
     * for the A at MIDI pitch 69; otherwise use the tuning frequency
     * specified in the application preferences (default 440Hz).
     */
    static bool isFrequencyInMidiRange(float frequency,
                                       float concertA = 0.0);
};


#endif