Android Open Source - Musicdroid Project To Midi Converter

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From Project

Back to project page Musicdroid.

License

The source code is released under:

GNU General Public License

Java Source Code

/*
 * Musicdroid: An on-device music generator for Android
 * Copyright (C) 2010-2014 The Catrobat Team
 * (<http://developer.catrobat.org/credits>)
 *//www  .  j a  v  a  2 s.c o m
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * An additional term exception under section 7 of the GNU Affero
 * General Public License, version 3, is available at
 * http://developer.catrobat.org/license_additional_term
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.catrobat.musicdroid.pocketmusic.note.midi;

import android.os.Environment;

import com.leff.midi.MidiFile;
import com.leff.midi.MidiTrack;
import com.leff.midi.event.ChannelEvent;
import com.leff.midi.event.ProgramChange;
import com.leff.midi.event.meta.Tempo;
import com.leff.midi.event.meta.Text;
import com.leff.midi.event.meta.TimeSignature;

import org.catrobat.musicdroid.pocketmusic.note.MusicalInstrument;
import org.catrobat.musicdroid.pocketmusic.note.NoteEvent;
import org.catrobat.musicdroid.pocketmusic.note.Project;
import org.catrobat.musicdroid.pocketmusic.note.Track;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class ProjectToMidiConverter {

    public static final String MIDI_FILE_EXTENSION = ".midi";
  public static final String MIDI_FILE_IDENTIFIER = "Musicdroid Midi File";
    public static final File MIDI_FOLDER = new File(Environment.getExternalStorageDirectory().toString() + File.separator + "musicdroid");

  private static final int MAX_CHANNEL = 16;

  private NoteEventToMidiEventConverter eventConverter;
  private ArrayList<MusicalInstrument> usedChannels;

  public ProjectToMidiConverter() {
    eventConverter = new NoteEventToMidiEventConverter();
    usedChannels = new ArrayList<MusicalInstrument>();
  }
    
  public void writeProjectAsMidi(Project project, String filename) throws IOException, MidiException {
    MidiFile midi = convertProject(project);

        if (!MIDI_FOLDER.exists()) {
            boolean success = MIDI_FOLDER.mkdir();

            if (!success) {
                throw new IOException("Could not create folder: " + MIDI_FOLDER);
            }
        }

    File file = new File(MIDI_FOLDER + File.separator + filename + MIDI_FILE_EXTENSION);

    midi.writeToFile(file);
  }

    public void writeProjectAsMidi(Project project, File file) throws IOException, MidiException {
        MidiFile midi = convertProject(project);

        midi.writeToFile(file);
    }

  private MidiFile convertProject(Project project) throws MidiException {
        for (int i = 0; i < project.size(); i++) {
            Track track = project.getTrack(i);

            if (0 == track.size()) {
                throw new MidiException("Cannot save a project with an empty track!");
            }
        }

    ArrayList<MidiTrack> tracks = new ArrayList<MidiTrack>();

    MidiTrack tempoTrack = createTempoTrackWithMetaInfo(project.getBeatsPerMinute());
    tracks.add(tempoTrack);

    for (int i = 0; i < project.size(); i++) {
      Track track = project.getTrack(i);
      int channel = addInstrumentAndGetChannel(track.getInstrument());

      MidiTrack noteTrack = createNoteTrack(track, channel);

      tracks.add(noteTrack);
    }

    return new MidiFile(MidiFile.DEFAULT_RESOLUTION, tracks);
  }

    private int addInstrumentAndGetChannel(MusicalInstrument instrument) throws MidiException {
    if (usedChannels.contains(instrument)) {
      return usedChannels.indexOf(instrument) + 1;
    } else if (usedChannels.size() == MAX_CHANNEL) {
      throw new MidiException("You cannot have more than " + MAX_CHANNEL + " channels!");
    } else {
      usedChannels.add(instrument);

      return usedChannels.indexOf(instrument) + 1;
    }
  }

  private MidiTrack createTempoTrackWithMetaInfo(int beatsPerMinute) {
    MidiTrack tempoTrack = new MidiTrack();

    Text text = new Text(0, 0, MIDI_FILE_IDENTIFIER);
    tempoTrack.insertEvent(text);

    Tempo tempo = new Tempo();
    tempo.setBpm(beatsPerMinute);
    tempoTrack.insertEvent(tempo);

    TimeSignature timeSignature = new TimeSignature();
    timeSignature.setTimeSignature(4, 4, TimeSignature.DEFAULT_METER, TimeSignature.DEFAULT_DIVISION);
    tempoTrack.insertEvent(timeSignature);

    return tempoTrack;
  }

  private MidiTrack createNoteTrack(Track track, int channel) throws MidiException {
    MidiTrack noteTrack = new MidiTrack();

    ProgramChange program = new ProgramChange(0, channel, track.getInstrument().getProgram());
    noteTrack.insertEvent(program);

    for (long tick : track.getSortedTicks()) {
      List<NoteEvent> noteEventList = track.getNoteEventsForTick(tick);

      for (NoteEvent noteEvent : noteEventList) {
        ChannelEvent channelEvent = eventConverter.convertNoteEvent(tick, noteEvent, channel);
        noteTrack.insertEvent(channelEvent);
      }
    }

    return noteTrack;
  }
}

Java Source Code List

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