在用Java播放时将midi文件输出到控制台

Question

我正在尝试读取midi文件并在播放音符，音符和力度时输出。 This工作得很好但是在播放音符时它不会实时输出数据。播放midi的代码：

package midistep;

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

import javax.sound.midi.MidiSystem;
import javax.sound.midi.Sequencer;

public class MidiReadAndPlay {

    public static void main(String[] args) throws Exception {
        Sequencer sequencer;
        sequencer = MidiSystem.getSequencer();
        sequencer.open();

        InputStream is = new BufferedInputStream(new FileInputStream(new File("midifile.mid")));
        sequencer.setSequence(is);
        sequencer.start();
    }
}

我之前提到的问题中的代码不会实时输出数据。它只是一次性输出。我想在播放音符时输出音序器数据，以便稍后使用。

Answer 1

及时输出音符数据的解决方案是添加带有自定义代码的接收器：

public class MidiReadAndPlay {

    public static Receiver synthRcvr = new CustomReceiver();
    public static Transmitter seqTrans;
    public static Synthesizer synth;
    public static Sequencer sequencer;
    public static Sequence sequence;

    public static void main(String[] args) throws Exception {      
        sequencer = MidiSystem.getSequencer();
        sequence = MidiSystem.getSequence(new File("midi.mid"));

        Sequencer sequencer = MidiSystem.getSequencer();
        seqTrans = sequencer.getTransmitter();
        seqTrans.setReceiver(synthRcvr);

        sequencer.open(); 
        sequencer.setSequence(sequence);

        sequencer.start();
    }

}

接收器：

public class CustomReceiver implements Receiver {

    public CustomReceiver() {

    }
    public static final int NOTE_ON = 0x90;
    public static final int NOTE_OFF = 0x80;
    public static final String[] NOTE_NAMES = {"C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"};

    @Override
    public void send(MidiMessage message, long timeStamp) {
        if (message instanceof ShortMessage) {
            ShortMessage sm = (ShortMessage) message;
            System.out.print("Channel: " + sm.getChannel() + " ");
            if (sm.getCommand() == NOTE_ON) {
                int key = sm.getData1();
                int octave = (key / 12)-1;
                int note = key % 12;
                String noteName = NOTE_NAMES[note];
                int velocity = sm.getData2();
                System.out.println("Note on, " + noteName + octave + " key=" + key + " velocity: " + velocity);
            } else if (sm.getCommand() == NOTE_OFF) {
                int key = sm.getData1();
                int octave = (key / 12)-1;
                int note = key % 12;
                String noteName = NOTE_NAMES[note];
                int velocity = sm.getData2();
                System.out.println("Note off, " + noteName + octave + " key=" + key + " velocity: " + velocity);
            } else {
                System.out.println("Command:" + sm.getCommand());
            }
        } else {
            System.out.println("Other message: " + message.getClass());
        }
    }

    @Override
    public void close() {

    }
}