Midi Generation

[Singing Boyo]

I've been learning about midi and trying my hand at creating something, but I'm stumped by the Sequencer-Synthesizer connection. I can't figure out why this doesn't generate sound when I use the sequencer. When I send messages directly to the Synthesizer's receiver, it works, but no such luck when I try to set the Sequencer's sequence and start it.

import javax.sound.midi.InvalidMidiDataException;
import javax.sound.midi.MidiEvent;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.MidiUnavailableException;
import javax.sound.midi.Receiver;
import javax.sound.midi.Sequence;
import javax.sound.midi.Sequencer;
import javax.sound.midi.ShortMessage;
import javax.sound.midi.Synthesizer;
import javax.sound.midi.Track;
import javax.sound.midi.Transmitter;

class MusiCube {

    /**
     * @param args
     * @throws MidiUnavailableException 
     * @throws InterruptedException 
     * @throws InvalidMidiDataException 
     */
    public static void main(String[] args) throws MidiUnavailableException, InterruptedException, InvalidMidiDataException {
        Sequence seq = new Sequence(Sequence.PPQ, 8);
        Track track = seq.createTrack ();
        ShortMessage msg1 = new ShortMessage ();
        msg1.setMessage (ShortMessage.PROGRAM_CHANGE, 1, 0, 0/*ignored*/);
        track.add (new MidiEvent (msg1, -1));
        ShortMessage msg2 = new ShortMessage();
        msg2.setMessage (ShortMessage.NOTE_ON, 1, 60, 90);
        track.add (new MidiEvent(msg2,2));
        
        
        Sequencer sequencer = MidiSystem.getSequencer ();
        sequencer.open ();
        
        Synthesizer synth = MidiSystem.getSynthesizer ();
        synth.open ();

        Transmitter seqTrans = sequencer.getTransmitter ();
        Receiver rec = synth.getReceiver ();
        
        seqTrans.setReceiver (rec);
       
        sequencer.setSequence (seq);
        sequencer.start ();
        
        //if I take out the Sequencer and use these, it works.  why?
        //rec.send (msg1, 1);
        //rec.send (msg2, 2);
        Thread.sleep(3000);
        sequencer.close();
        synth.close ();
    }

}

Probably nothing incredibly big, but I don't know much about midi just yet, so I'm stuck. Thanks in advance for any and all help!

[Dark]

I never really messed with midi, but just one observation that might help you in the future. If you use import javax.sound.midi.*; it will import everything you are trying to import with just one import statement.

[Singing Boyo]

Eclipse has trained me to just import my unknown classes with a keyboard shortcut... should go back to Notepad++ for a bit, just to remind myself of things like that. Or just figure out how to make eclipse auto-wildcard the long import lists.

[DarrylBurke]

Add a NOTE_OFF.

db

[Singing Boyo]

Works, thanks. That begs the question though: why? Does something (Sequence/Track or Sequencer) look for a matching NOTE_OFF before executing/transmitting a NOTE_ON? It seems odd to me that it would work when I send the messages directly to the Receiver, but not when I put them in a Track.

[DarrylBurke]

Probably because the eotEvent (end-of-Track) is at the same tick as the NOTE_ON so the Track comes to an end before the note can be heard. Adding any valid ShortMessage -- even another NOTE_ON -- results in the first note being heard.

Read the source of Track.add(MidiEvent event) if you want to know more.

db

[Singing Boyo]

Right, that makes sense. Hadn't reached MetaEventListeners and the eotEvent yet, so I didn't realize that the Sequencer was treating the track as if it was done. Thanks again!

[JosAH]

Eclipse has trained me to just import my unknown classes with a keyboard shortcut... should go back to Notepad++ for a bit, just to remind myself of things like that. Or just figure out how to make eclipse auto-wildcard the long import lists.

I just read this thread for the first time so my reply might be a little late: keep it the way Eclipse does for you: import single files, not wildcards. A simple Ctrl-Shift-O organizes the imports for you anyway, so there's no need to import half the world in order to reduce the number of keystrokes; that's what IDEs are for.

kind regards,

Jos