java midi sequencer

Discussion in 'General Linux' started by eubulide, Jul 18, 2012.

  1. eubulide

    eubulide New Member

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    Hi everyone,
    I am reading a book called "Head First Java" by Kathy Sierra and Bert Bates. One example piece of code uses a MIDI sequencer to generate a sound.
    Unfortunately it doesn't work on Linux. When I run it I only hear a kind of knock (it's supposed to be a piano note). I don't know anything about sound and MIDI devices, so I don't know how to fix the problem.
    I tried it on two computers, one with Ubuntu and one with Mageia.

    I give the code below.
    After compiling it I execute the command with different arguments:
    java MiniMusicCmdLine 102 30
    java MiniMusicCmdLine 80 20
    java MiniMusicCmdLine 40 70

    They're supposed to produce notes of different pitch, but I always hear the same short knock.

    I welcome any help at the beginner level.

    -----------------------

    import javax.sound.midi.*;

    public class MiniMiniMusicCmdLine {


    public static void main(String[] args) {
    MiniMiniMusicCmdLine mini = new MiniMiniMusicCmdLine();
    if (args.length < 2) {
    System.out.println("Don't forget the instrument and note args");
    } else {
    int instrument = Integer.parseInt(args[0]);
    int note = Integer.parseInt(args[1]);
    mini.play(instrument,note);
    }
    } // close main

    public void play(int instrument, int note) {
    try {
    Sequencer player = MidiSystem.getSequencer();
    player.open();
    Sequence seq = new Sequence(Sequence.PPQ, 4);
    Track track = seq.createTrack();

    MidiEvent event = null;

    ShortMessage first = new ShortMessage();
    first.setMessage(192, 1, instrument, 0);
    MidiEvent changeInstrument = new MidiEvent(first, 1);
    track.add(changeInstrument);

    ShortMessage a = new ShortMessage();
    a.setMessage(144, 1, note, 100);
    MidiEvent noteOn = new MidiEvent(a, 1);
    track.add(noteOn);

    ShortMessage b = new ShortMessage();
    a.setMessage(128, 1, note, 100);
    MidiEvent noteOff = new MidiEvent(b, 16);
    track.add(noteOff);

    player.setSequence(seq);
    player.start();
    } catch (Exception ex) {ex.printStackTrace();}
    } // close play

    } // close class

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