I just finished my first Processing sketch, which accepts input from MIDI sources, and displays a real-time visualization.  I used themidibus for the midi interface.

Now after I've done this, I realize one other use of this (so it's easier to show a demo on the web) is to have it load a midi file and visualize from it.  Is there a way to connect a java sequencer as transmitter and setup themidibus as receiver, or something like that, using only Processing, to achieve the result?

I finally could get it to load a midi file and extract tracks information :

Code:

import javax.sound.midi.*;
import java.io.File;

String filename = "D:/mypath/data/test.mid";
File f = new File(filename);
try {
  Sequence s = MidiSystem.getSequence(f);
  println("Division type: " + s.getDivisionType());
  println("Duration (microsec): " + s.getMicrosecondLength());
  println("Resolution: " + s.getResolution());
  println("Duration (ticks): " + s.getTickLength());
  Track[] tracks = s.getTracks();
  println("Tracks: " + tracks.length);
  for(int i = 0; i < tracks.length; i++) {
    Track t = tracks[i];
    println("  Track " + (i+1));
    println("    Events: " + t.size());
    println("    Duration (ticks): " + t.ticks());
  }
}
catch(Exception e) {} 

Next step : extract all note-on, note-off and control change events, put them in an array, and play them back on tempo.

Yes, it'd be great if MIDI file read is supported.  When I write code to respond to MIDI messages, it'd be nice if I don't have to consider where it comes from, whether it comes from MIDI file or from an actual instrument, or both at the same time...  Having a common interface makes things easier to be re-useable.  MIDIbus would be a great abstraction to build this, as theBUS supports multiple inputs all going to the same input bus.  So is this possible?