MIDI Change resolution (TPQN) and re timing events. - Java javax.sound.midi

Java examples for javax.sound.midi:MidiEvent

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Description

MIDI Change resolution (TPQN) and re timing events.

Demo Code


//package com.java2s;

import javax.sound.midi.InvalidMidiDataException;

import javax.sound.midi.MidiEvent;
import javax.sound.midi.Sequence;

import javax.sound.midi.Track;

public class Main {
    /**// w w w .jav a2  s.  c o m
     * Change resolution (TPQN) and retiming events.
     * @param seq Sequence to be processed.
     * @param resolution Ticks per quarter note of new sequence.
     * @return New sequence with new resolution.
     * @throws InvalidMidiDataException throw if MIDI data is invalid.
     */
    public static Sequence ChangeResolution(Sequence sourceSeq,
            int resolution) 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
        for (int trackIndex = 0; trackIndex < sourceSeq.getTracks().length; trackIndex++) {
            Track sourceTrack = sourceSeq.getTracks()[trackIndex];
            Track track = seq.createTrack();

            // process all events
            double timingRate = (double) resolution
                    / sourceSeq.getResolution();
            for (int eventIndex = 0; eventIndex < sourceTrack.size(); eventIndex++) {
                MidiEvent sourceEvent = sourceTrack.get(eventIndex);
                MidiEvent event = new MidiEvent(sourceEvent.getMessage(),
                        Math.round(sourceEvent.getTick() * timingRate));
                track.add(event);
            }
        }

        // if the target resolution is shorter than source resolution,
        // events at different timing might be located at the same timing.
        // As a result, there might be zero-length note and/or
        // same control changes at the same timing.
        // 
        // Probably, they should be removed for better conversion.
        // I do not remove them anyway at the moment,
        // because it does not cause any major problems.

        return seq;
    }
}

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