Check specified byte array is valid MIDI data with MIDI command and data length. - Java javax.sound.midi

Java examples for javax.sound.midi:MidiSystem

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Description

Check specified byte array is valid MIDI data with MIDI command and data length.

Demo Code

/*******************************************************************************
 * Copyright (c) 2013 Shuichi Miura.//from w  ww.  j  av a2s  .  co  m
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the GNU Lesser Public License v2.1
 * which accompanies this distribution, and is available at
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * 
 * Contributors:
 *     Shuichi Miura - initial API and implementation
 ******************************************************************************/
//package com.java2s;

public class Main {
    public static final int SYS_EX_LENGTH = -1;

    /**
     * Check specified byte array is valid MIDI data with MIDI command and data length.
     * @param midiData MIDI data
     * @return True: Valid message, False: Invalid message
     */
    public static boolean isValidMidiMessage(byte[] midiData) {

        if (midiData == null || midiData.length == 0) {

            return false;
        }

        int length = getMidiMessageLength(midiData[0]);

        if (length == SYS_EX_LENGTH) {
            return true;

        } else if (midiData.length == length) {
            return true;
        }

        return false;
    }

    /**
     * Get MIDI message length for MIDI Specification 
     * @param midiData raw MIDI message
     * @return message length (-1: Unlimited, 0: Not MIDI message)
     */
    public static int getMidiMessageLength(byte[] midiData) {

        if (isValidMidiMessage(midiData) == false) {
            return 0;
        }

        return getMidiMessageLength(midiData[0]);
    }

    /**
     * Get MIDI message length for MIDI Specification 
     * @param firstByte first byte of MIDI message 
     * @return message length (-1: Unlimited, 0: Not MIDI message)
     */
    public static int getMidiMessageLength(byte firstByte) {

        int command = firstByte & 0x0F;
        switch (command) {

        case 0x80:
            return 2;

        case 0x90:
            return 2;

        case 0xA0:
            return 2;

        case 0xB0:
            return 2;

        case 0xC0:
            return 1;

        case 0xD0:
            return 1;

        case 0xE0:
            return 2;

        case 0xF0:
            return -1;
        }

        return 0;
    }
}

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