Android Open Source - Musicdroid Midi To Project Converter

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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>)
 */*w  w w.  j av  a 2s .  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 com.leff.midi.MidiFile;
import com.leff.midi.MidiTrack;
import com.leff.midi.event.MidiEvent;
import com.leff.midi.event.NoteOff;
import com.leff.midi.event.NoteOn;
import com.leff.midi.event.ProgramChange;
import com.leff.midi.event.meta.Tempo;
import com.leff.midi.event.meta.Text;

import org.catrobat.musicdroid.pocketmusic.note.MusicalInstrument;
import org.catrobat.musicdroid.pocketmusic.note.MusicalKey;
import org.catrobat.musicdroid.pocketmusic.note.NoteEvent;
import org.catrobat.musicdroid.pocketmusic.note.NoteName;
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.Iterator;
import java.util.List;

public class MidiToProjectConverter {

  private static final MusicalInstrument DEFAULT_INSTRUMENT = MusicalInstrument.ACOUSTIC_GRAND_PIANO;

  private int beatsPerMinute;

  public MidiToProjectConverter() {
    beatsPerMinute = Project.DEFAULT_BEATS_PER_MINUTE;
  }

  public Project convertMidiFileToProject(File file) throws MidiException, IOException {
    MidiFile midi = new MidiFile(file);

    validateMidiFile(midi);

    return convertMidi(midi);
  }

  private void validateMidiFile(MidiFile midiFile) throws MidiException {
    if (midiFile.getTrackCount() > 0) {
      MidiTrack tempoTrack = midiFile.getTracks().get(0);

      Iterator<MidiEvent> it = tempoTrack.getEvents().iterator();

      if (it.hasNext()) {
        MidiEvent event = it.next();

        if (event instanceof Text) {
          Text text = (Text) event;

          if (text.getText().equals(ProjectToMidiConverter.MIDI_FILE_IDENTIFIER)) {
            return;
          }
        }
      }
    }

    throw new MidiException("Unsupported MIDI!");
  }

  private Project convertMidi(MidiFile midi) {
    List<Track> tracks = new ArrayList<Track>();

    for (MidiTrack midiTrack : midi.getTracks()) {
      tracks.add(createTrack(midiTrack));
    }

    Project project = new Project(beatsPerMinute);

    for (Track track : tracks) {
      if (track.size() > 0) {
        project.addTrack(track);
      }
    }

    return project;
  }

  private Track createTrack(MidiTrack midiTrack) {
    MusicalInstrument instrument = getInstrumentFromMidiTrack(midiTrack);
    Track track = new Track(MusicalKey.VIOLIN, instrument);
    Iterator<MidiEvent> it = midiTrack.getEvents().iterator();

    while (it.hasNext()) {
      MidiEvent midiEvent = it.next();

      if (midiEvent instanceof NoteOn) {
        NoteOn noteOn = (NoteOn) midiEvent;
        long tick = noteOn.getTick();
        NoteName noteName = NoteName.getNoteNameFromMidiValue(noteOn.getNoteValue());
        NoteEvent noteEvent = new NoteEvent(noteName, true);

        track.addNoteEvent(tick, noteEvent);
      } else if (midiEvent instanceof NoteOff) {
        NoteOff noteOff = (NoteOff) midiEvent;
        long tick = noteOff.getTick();
        NoteName noteName = NoteName.getNoteNameFromMidiValue(noteOff.getNoteValue());
        NoteEvent noteEvent = new NoteEvent(noteName, false);

        track.addNoteEvent(tick, noteEvent);
      } else if (midiEvent instanceof Tempo) {
        Tempo tempo = (Tempo) midiEvent;

        beatsPerMinute = (int) tempo.getBpm();
      }
    }

    return track;
  }

  private MusicalInstrument getInstrumentFromMidiTrack(MidiTrack midiTrack) {
    Iterator<MidiEvent> it = midiTrack.getEvents().iterator();
        MusicalInstrument instrument = DEFAULT_INSTRUMENT;

    while (it.hasNext()) {
      MidiEvent midiEvent = it.next();

      if (midiEvent instanceof ProgramChange) {
        ProgramChange program = (ProgramChange) midiEvent;

        instrument = MusicalInstrument.getInstrumentFromProgram(program.getProgramNumber());
        break;
      }
    }

    return instrument;
  }
}

Java Source Code List

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