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MidiStochaster.cpp
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MidiStochaster.cpp
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//
// MidiStochaster.cpp
//
// Created by Jack Atherton on 10/13/12.
// Copyright (c) 2012 Jack Atherton. All rights reserved.
//
#include "MidiStochaster.h"
#include <cstdlib>
double randomDouble (double min, double max);
int randomInt(int min, int max);
MidiStochaster::MidiStochaster() {
MidiMessageSequence track;
init(track);
}
MidiStochaster::MidiStochaster(MidiMessageSequence const& track) {
init(track);
}
void MidiStochaster::init(MidiMessageSequence const& originalTrack) {
srand(time(0));
ScopedPointer<MidiMessageSequence> track (new MidiMessageSequence(originalTrack));
track->updateMatchedPairs();
int numEvents = track->getNumEvents();
if (numEvents == 0) {
//No Events handling
//...
goodSource = false;
return;
}
int numNotes = 0;
for (int i = 0; i < numEvents; i++) {
if (track->getEventPointer(i)->message.isNoteOn()) {
numNotes++;
}
}
if (numNotes == 0) {
//No Notes handling
//...
return;
}
pitches = new std::vector<int>(0);
MidiMessageSequence::MidiEventHolder* eventHolder = track->getEventPointer(0);
int i = 0;
while (!eventHolder->message.isNoteOn()) {
starter.addEvent(eventHolder->message);
i++;
eventHolder = track->getEventPointer(i);
}
pitches->push_back(eventHolder->message.getNoteNumber());
lowVelocity = (int) eventHolder->message.getVelocity();
highVelocity = lowVelocity;
lowNoteLength = eventHolder->noteOffObject->message.getTimeStamp() - eventHolder->message.getTimeStamp();
highNoteLength = lowNoteLength;
if (numNotes == 1) {
//One Note handling
//...
return;
}
lowRestLength = -1.0;
highRestLength = lowRestLength;
lowNegRestLength = 1.0;
highNegRestLength = lowNegRestLength;
numPosRest = 0;
numNegRest = 0;
double lastNoteEndPoint;
bool brokeInner = false;
for (i = i+1; i < numEvents; i++) {
lastNoteEndPoint = eventHolder->noteOffObject->message.getTimeStamp();
eventHolder = track->getEventPointer(i);
while(!eventHolder->message.isNoteOn()) {
i++;
if (i >= numEvents) {
brokeInner = true;
break;
}
eventHolder = track->getEventPointer(i);
}
if(brokeInner) {
break;
}
double restLength = eventHolder->message.getTimeStamp() - lastNoteEndPoint;
addRest(restLength);
addNote(eventHolder, i, *track);
}
negRestProbability = ((double) numNegRest) / ((double) (numNegRest + numPosRest));
if (negRestProbability > .9) {
if (negRestProbability == 1.0) {
lowRestLength = 1;
highRestLength = 1;
}
negRestProbability = .9;
}
goodSource = true;
}
void MidiStochaster::addNote(MidiMessageSequence::MidiEventHolder* note, int i, MidiMessageSequence const& track) {
pitches->push_back(note->message.getNoteNumber());
int noteVelocity = (int) note->message.getVelocity();
if (noteVelocity > highVelocity) {
highVelocity = noteVelocity;
} else if (noteVelocity < lowVelocity) {
lowVelocity = noteVelocity;
}
double noteLength = note->noteOffObject->message.getTimeStamp() - note->message.getTimeStamp();
if (noteLength > highNoteLength) {
highNoteLength = noteLength;
} else if (noteLength < lowNoteLength) {
lowNoteLength = noteLength;
}
}
void MidiStochaster::addRest(double restLength) {
if (restLength < 0.0) {
//Is a negative distance / overlapping note
numNegRest++;
if (lowNegRestLength < 0.0) {
if (restLength > highNegRestLength) {
//Mark it's the highest neg we've seen yet
highNegRestLength = restLength;
} else if (restLength < lowNegRestLength) {
//Mark it's the lowest neg we've seen yet
lowNegRestLength = restLength;
}
//Else do nothing
} else {
//We haven't seen any negs yet, this is the first
lowNegRestLength = restLength;
highNegRestLength = lowNegRestLength;
}
} else {
//Is a regular rest
numPosRest++;
if (lowRestLength > 0.0) {
if (restLength > highRestLength) {
//Mark it's the longest rest we've seen yet
highRestLength = restLength;
} else if (restLength < lowRestLength) {
//Mark it's the shortest rest we've seen yet
lowRestLength = restLength;
}
//Else do nothing
} else {
//We haven't seen any rests yet, this is the first
lowRestLength = restLength;
highRestLength = lowRestLength;
}
}
}
MidiMessageSequence* MidiStochaster::createMelody() {
return createMelody(0, 0, 1);
}
MidiMessageSequence* MidiStochaster::createMelody(int minOctaveOffset, int maxOctaveOffset, double speedFactor) {
int currentOctaveOffset;
if (minOctaveOffset <= 0) {
currentOctaveOffset = 0;
} else {
currentOctaveOffset = minOctaveOffset;
}
int randInt1 = randomInt(100, 200);
double stopProbability = (double) randInt1 / (randInt1 + 1);
int randInt2 = randomInt(4, 10);
double octaveSwitchProbability = (double) randInt2 / (randInt2 + 1);
double currentTime = 0.0;
MidiMessageSequence* melody = new MidiMessageSequence(starter);
if (!goodSource) {
return melody;
}
while (randomDouble(0,1) < stopProbability) {
int notePitch = pitches->at(randomInt(0, pitches->size() - 1)) + 12 * currentOctaveOffset;
while (notePitch < 0) {
notePitch+=12;
currentOctaveOffset++;
minOctaveOffset++;
}
while (notePitch > 127) {
notePitch-=12;
currentOctaveOffset--;
maxOctaveOffset--;
}
int noteVelocity = randomInt(lowVelocity, highVelocity);
int noteLength = randomDouble(lowNoteLength, highNoteLength) * (1.0 / speedFactor);
int nextRestLength;
if (randomDouble(0,1) < negRestProbability) {
nextRestLength = randomDouble(lowNegRestLength, highNegRestLength) * 1.0 / speedFactor;
} else {
nextRestLength = randomDouble(lowRestLength, highRestLength) * 1.0 / speedFactor;
}
MidiMessage noteDown = MidiMessage::noteOn(1, notePitch, (uint8_t) noteVelocity);
noteDown.setTimeStamp(currentTime);
MidiMessage noteUp = MidiMessage::noteOff(1, notePitch);
noteUp.setTimeStamp(currentTime + noteLength);
melody->addEvent(noteDown);
melody->addEvent(noteUp);
melody->updateMatchedPairs();
currentTime += noteLength + nextRestLength;
if (randomDouble(0,1) > octaveSwitchProbability) {
currentOctaveOffset = randomInt(minOctaveOffset, maxOctaveOffset);
}
}
return melody;
}
double randomDouble (double min, double max) {
double zeroOne = (double) rand() / RAND_MAX;
return min + zeroOne * (max - min);
}
int randomInt(int min, int max) {
return min + rand() % (max + 1 - min);
}