javax.sound.midi: public class: MetaMessage

javax.sound.midi
public class: MetaMessage [javadoc | source]

java.lang.Object
   javax.sound.midi.MidiMessage
      javax.sound.midi.MetaMessage

All Implemented Interfaces:
Cloneable

Direct Known Subclasses:
ImmutableEndOfTrack

A MetaMessage is a MidiMessage that is not meaningful to synthesizers, but that can be stored in a MIDI file and interpreted by a sequencer program. (See the discussion in the MidiMessage class description.) The Standard MIDI Files specification defines various types of meta-events, such as sequence number, lyric, cue point, and set tempo. There are also meta-events for such information as lyrics, copyrights, tempo indications, time and key signatures, markers, etc. For more information, see the Standard MIDI Files 1.0 specification, which is part of the Complete MIDI 1.0 Detailed Specification published by the MIDI Manufacturer's Association (http://www.midi.org).

When data is being transported using MIDI wire protocol, a ShortMessage with the status value 0xFF represents a system reset message. In MIDI files, this same status value denotes a MetaMessage. The types of meta-message are distinguished from each other by the first byte that follows the status byte 0xFF. The subsequent bytes are data bytes. As with system exclusive messages, there are an arbitrary number of data bytes, depending on the type of MetaMessage.

Also see:

MetaEventListener

author: David - Rivas

author: Kara - Kytle

Field Summary
public static final int	META	Status byte for `MetaMessage` (0xFF, or 255), which is used in MIDI files. It has the same value as SYSTEM_RESET, which is used in the real-time "MIDI wire" protocol. Also see: MidiMessage#getStatus

Fields inherited from javax.sound.midi.MidiMessage:
data, length

Constructor:

Constructor:
public MetaMessage() { //super(defaultMessage); this(defaultMessage); } Constructs a new `MetaMessage`. The contents of the message are not set here; use setMessage to set them subsequently.
protected MetaMessage(byte[] data) { super(data); //$$fb 2001-10-06: need to calculate dataLength. Fix for bug #4511796 if (data.length >=3) { dataLength=data.length-3; int pos=2; while (pos< data.length && (data[pos] & 0x80)!=0) { dataLength--; pos++; } } } Constructs a new `MetaMessage`. Parameters: `data` - an array of bytes containing the complete message. The message data may be changed using the `setMessage` method. Also see: setMessage

 public MetaMessage() {
                                
        //super(defaultMessage);
        this(defaultMessage);
}

Constructs a new MetaMessage. The contents of the message are not set here; use

setMessage

 protected MetaMessage(byte[] data) {
        super(data);
        //$$fb 2001-10-06: need to calculate dataLength. Fix for bug #4511796
        if (data.length >=3) {
            dataLength=data.length-3;
            int pos=2;
            while (pos< data.length && (data[pos] & 0x80)!=0) {
                dataLength--; pos++;
            }
        }
}

Constructs a new MetaMessage.

Parameters:

data - an array of bytes containing the complete message. The message data may be changed using the setMessage method.

Also see:

setMessage

Method from javax.sound.midi.MetaMessage Summary:
clone, getData, getType, setMessage

Methods from javax.sound.midi.MidiMessage:
clone, getLength, getMessage, getStatus, setMessage

Methods from java.lang.Object:
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method from javax.sound.midi.MetaMessage Detail:
public Object clone() { byte[] newData = new byte[length]; System.arraycopy(data, 0, newData, 0, newData.length); MetaMessage event = new MetaMessage(newData); return event; } Creates a new object of the same class and with the same contents as this object.
public byte[] getData() { byte[] returnedArray = new byte[dataLength]; System.arraycopy(data, (length - dataLength), returnedArray, 0, dataLength); return returnedArray; } Obtains a copy of the data for the meta message. The returned array of bytes does not include the status byte or the message length data. The length of the data for the meta message is the length of the array. Note that the length of the entire message includes the status byte and the meta message type byte, and therefore may be longer than the returned array.
public int getType() { if (length >=2) { return data[1] & 0xFF; } return 0; } Obtains the type of the `MetaMessage`.
public void setMessage(int type, byte[] data, int length) throws InvalidMidiDataException { if (type >= 128 \|\| type < 0) { throw new InvalidMidiDataException("Invalid meta event with type " + type); } if ((length > 0 && length > data.length) \|\| length < 0) { throw new InvalidMidiDataException("length out of bounds: "+length); } this.length = 2 + getVarIntLength(length) + length; this.dataLength = length; this.data = new byte[this.length]; this.data[0] = (byte) META; // status value for MetaMessages (meta events) this.data[1] = (byte) type; // MetaMessage type writeVarInt(this.data, 2, length); // write the length as a variable int if (length > 0) { System.arraycopy(data, 0, this.data, this.length - this.dataLength, this.dataLength); } } Sets the message parameters for a `MetaMessage`. Since only one status byte value, `0xFF`, is allowed for meta-messages, it does not need to be specified here. Calls to `getStatus` return `0xFF` for all meta-messages. The `type` argument should be a valid value for the byte that follows the status byte in the `MetaMessage`. The `data` argument should contain all the subsequent bytes of the `MetaMessage`. In other words, the byte that specifies the type of `MetaMessage` is not considered a data byte.

Method from javax.sound.midi.MetaMessage Detail:

 public Object clone() {
        byte[] newData = new byte[length];
        System.arraycopy(data, 0, newData, 0, newData.length);
        MetaMessage event = new MetaMessage(newData);
        return event;
}

Creates a new object of the same class and with the same contents as this object.

 public byte[] getData() {
        byte[] returnedArray = new byte[dataLength];
        System.arraycopy(data, (length - dataLength), returnedArray, 0, dataLength);
        return returnedArray;
}

Obtains a copy of the data for the meta message. The returned array of bytes does not include the status byte or the message length data. The length of the data for the meta message is the length of the array. Note that the length of the entire message includes the status byte and the meta message type byte, and therefore may be longer than the returned array.

 public int getType() {
        if (length >=2) {
            return data[1] & 0xFF;
        }
        return 0;
}

MetaMessage

 public  void setMessage(int type,
    byte[] data,
    int length) throws InvalidMidiDataException {
        if (type  >= 128 || type <  0) {
            throw new InvalidMidiDataException("Invalid meta event with type " + type);
        }
        if ((length  > 0 && length  > data.length) || length <  0) {
            throw new InvalidMidiDataException("length out of bounds: "+length);
        }
        this.length = 2 + getVarIntLength(length) + length;
        this.dataLength = length;
        this.data = new byte[this.length];
        this.data[0] = (byte) META;        // status value for MetaMessages (meta events)
        this.data[1] = (byte) type;        // MetaMessage type
        writeVarInt(this.data, 2, length); // write the length as a variable int
        if (length  > 0) {
            System.arraycopy(data, 0, this.data, this.length - this.dataLength, this.dataLength);
        }
}

MetaMessage

0xFF

getStatus

0xFF

The type argument should be a valid value for the byte that follows the status byte in the MetaMessage. The data argument should contain all the subsequent bytes of the MetaMessage. In other words, the byte that specifies the type of MetaMessage is not considered a data byte.