MidiToAudioRenderer.java

/*
 * Copyright (c) 2007 by Karl Helgason
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package com.sun.kh;

import javax.sound.midi.MetaMessage;
import javax.sound.midi.MidiEvent;
import javax.sound.midi.MidiMessage;
import javax.sound.midi.Receiver;
import javax.sound.midi.Sequence;
import javax.sound.midi.Soundbank;
import javax.sound.midi.Track;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;

import com.sun.gervill.SoftSynthesizer;

/**
 * This class can be used to create an audio stream from a MIDI sequence
 * using a user-defined soundfont.
 * 
 * Originally this class has been created by Karl Helgason as "Midi2WavRender.java".
 * 
 * @author Karl Helgason, Jan Trukenmüller
 */
public class MidiToAudioRenderer {

	/*
	 * Render sequence using selected or default soundbank into an audio stream.
	 */
	public static AudioInputStream render(Soundbank soundbank, Sequence sequence,
			AudioFormat format, SoftSynthesizer synth) throws Exception {
		
		// Open AudioStream from AudioSynthesizer.
		AudioInputStream stream = synth.openStream(format, null);

		// Load user-selected Soundbank into AudioSynthesizer.
		if (soundbank != null) {
			Soundbank defsbk = synth.getDefaultSoundbank();
			if (defsbk != null)
				synth.unloadAllInstruments(defsbk);
			synth.loadAllInstruments(soundbank);
		}
		
		// Play Sequence into AudioSynthesizer Receiver.
		double total = send(sequence, synth.getReceiver());

		// Calculate how many frames the file must have.
		long targetFrames = (long) (stream.getFormat().getFrameRate() * (total + 4));
		stream = new AudioInputStream(stream, stream.getFormat(), targetFrames);
		
		return stream;
	}

	/*
	 * Send MIDI Sequence to Receiver using timestamps.
	 */
	private static double send(Sequence seq, Receiver recv) {
		float divtype = seq.getDivisionType();
		assert (seq.getDivisionType() == Sequence.PPQ);
		Track[] tracks = seq.getTracks();
		int[] trackspos = new int[tracks.length];
		int mpq = 500000;
		int seqres = seq.getResolution();
		long lasttick = 0;
		long curtime = 0;
		while (true) {
			MidiEvent selevent = null;
			int seltrack = -1;
			for (int i = 0; i < tracks.length; i++) {
				int trackpos = trackspos[i];
				Track track = tracks[i];
				if (trackpos < track.size()) {
					MidiEvent event = track.get(trackpos);
					if (selevent == null
							|| event.getTick() < selevent.getTick()) {
						selevent = event;
						seltrack = i;
					}
				}
			}
			if (seltrack == -1)
				break;
			trackspos[seltrack]++;
			long tick = selevent.getTick();
			if (divtype == Sequence.PPQ)
				curtime += ((tick - lasttick) * mpq) / seqres;
			else
				curtime = (long) ((tick * 1000000.0 * divtype) / seqres);
			lasttick = tick;
			MidiMessage msg = selevent.getMessage();
			if (msg instanceof MetaMessage) {
				if (divtype == Sequence.PPQ)
					if (((MetaMessage) msg).getType() == 0x51) {
						byte[] data = ((MetaMessage) msg).getData();
						mpq = ((data[0] & 0xff) << 16)
								| ((data[1] & 0xff) << 8) | (data[2] & 0xff);
					}
			}
			else {
				if (recv != null)
					recv.send(msg, curtime);
			}
		}
		return curtime / 1000000.0;
	}

}