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/*
* Copyright 2010 Phil Burk, Mobileer Inc
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.jsyn.midi;
/**
* Constants that define the MIDI standard.
*
* @author Phil Burk (C) 2010 Mobileer Inc
*/
public class MidiConstants {
// Basic commands.
public static final int NOTE_OFF = 0x80;
public static final int NOTE_ON = 0x90;
public static final int POLYPHONIC_AFTERTOUCH = 0xA0;
public static final int CONTROL_CHANGE = 0xB0;
public static final int PROGRAM_CHANGE = 0xC0;
public static final int CHANNEL_AFTERTOUCH = 0xD0;
public static final int PITCH_BEND = 0xE0;
public static final int SYSTEM_COMMON = 0xF0;
public static final int PITCH_BEND_CENTER = 8192;
public static final String PITCH_NAMES[] = {
"C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"
};
/**
* Calculate frequency in Hertz based on MIDI pitch. Middle C is 60.0. You can use fractional
* pitches so 60.5 would give you a pitch half way between C and C#.
*/
static final double CONCERT_A_FREQUENCY = 440.0;
static final double CONCERT_A_PITCH = 69.0;
public static double convertPitchToFrequency(double pitch) {
return CONCERT_A_FREQUENCY * Math.pow(2.0, ((pitch - CONCERT_A_PITCH) / 12.0));
}
/**
* Calculate MIDI pitch based on frequency in Hertz. Middle C is 60.0.
*/
public static double convertFrequencyToPitch(double frequency) {
return CONCERT_A_PITCH + (12 * Math.log(frequency / CONCERT_A_FREQUENCY) / Math.log(2.0));
}
}
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