MIDI Change resolution (TPQN) without re-timing events. - Java javax.sound.midi

Java examples for javax.sound.midi:MidiEvent

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Description

MIDI Change resolution (TPQN) without re-timing events.

Demo Code


import java.util.ArrayList;
import java.util.List;
import javax.sound.midi.InvalidMidiDataException;
import javax.sound.midi.MetaMessage;
import javax.sound.midi.MidiEvent;
import javax.sound.midi.Sequence;
import javax.sound.midi.ShortMessage;
import javax.sound.midi.Track;

public class Main{
    public static final int META_TEMPO = 0x51;
    /**/*from   ww w .  j a v  a  2 s  .  co m*/
     * Change resolution (TPQN) without retiming events.
     * @param seq Sequence to be processed.
     * @param resolution Ticks per quarter note of new sequence.
     * @param adjustTempo true if adjust the tempo value to keep the song tempo.
     * @return New sequence with new resolution.
     * @throws InvalidMidiDataException throw if MIDI data is invalid.
     */
    public static Sequence AssumeResolution(Sequence sourceSeq,
            int resolution, boolean adjustTempo)
            throws InvalidMidiDataException {
        // sequence must be tick-based
        if (sourceSeq.getDivisionType() != Sequence.PPQ) {
            throw new UnsupportedOperationException(
                    "SMPTE is not supported.");
        }

        Sequence seq = new Sequence(sourceSeq.getDivisionType(), resolution);

        // process all input tracks
        double tempoScale = (double) sourceSeq.getResolution()
                / seq.getResolution();
        for (int trackIndex = 0; trackIndex < sourceSeq.getTracks().length; trackIndex++) {
            Track sourceTrack = sourceSeq.getTracks()[trackIndex];
            Track track = seq.createTrack();

            // process all events
            for (int eventIndex = 0; eventIndex < sourceTrack.size(); eventIndex++) {
                MidiEvent sourceEvent = sourceTrack.get(eventIndex);
                MidiEvent event = new MidiEvent(sourceEvent.getMessage(),
                        sourceEvent.getTick());
                if (adjustTempo) {
                    if (event.getMessage() instanceof MetaMessage) {
                        MetaMessage message = (MetaMessage) event
                                .getMessage();
                        if (message.getType() == MidiUtil.META_TEMPO) {
                            byte[] data = message.getData();
                            if (data.length != 3) {
                                throw new InvalidMidiDataException(
                                        "Illegal tempo event.");
                            }

                            int sourceTempo = ((data[0] & 0xff) << 16)
                                    | ((data[1] & 0xff) << 8)
                                    | (data[2] & 0xff);
                            int newTempo = (int) Math.floor(sourceTempo
                                    / tempoScale);
                            data = new byte[] {
                                    (byte) ((newTempo >> 16) & 0xff),
                                    (byte) ((newTempo >> 8) & 0xff),
                                    (byte) (newTempo & 0xff) };
                            message.setMessage(MidiUtil.META_TEMPO, data,
                                    data.length);
                        }
                    }
                }
                track.add(event);
            }
        }
        return seq;
    }
}

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