Question

我是Java中的Java和声音API的新手，我编写了这段代码，我无法理解不同声音来自不同行的声音，因为我没有更改代码中的乐器。

import java.awt.*;
 import javax.swing.*;
 import javax.sound.midi.*;
 import java.util.*;
 import java.awt.event.*;

public class BeatBox {

JPanel mainPanel;
ArrayList<JCheckBox> checkboxList;
Sequencer sequencer;
Sequence sequence;
Track track;
JFrame theFrame;

String[] instrumentNames = {"Bass Drum", "Closed Hi-Hat", 
   "Open Hi-Hat","Acoustic Snare", "Crash Cymbal", "Hand Clap", 
   "High Tom", "Hi Bongo", "Maracas", "Whistle", "Low Conga", 
   "Cowbell", "Vibraslap", "Low-mid Tom", "High Agogo", 
   "Open Hi Conga"};
int[] instruments = {35,42,46,38,49,39,50,60,70,72,64,56,58,47,67,63};


public static void main (String[] args) {
    new BeatBox().buildGUI();
}

public void buildGUI() {
    theFrame = new JFrame("Cyber BeatBox");
    theFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    BorderLayout layout = new BorderLayout();
    JPanel background = new JPanel(layout);
    background.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));

    checkboxList = new ArrayList<JCheckBox>();
    Box buttonBox = new Box(BoxLayout.Y_AXIS);

    JButton start = new JButton("Start");
    start.addActionListener(new MyStartListener());
    buttonBox.add(start);         

    JButton stop = new JButton("Stop");
    stop.addActionListener(new MyStopListener());
    buttonBox.add(stop);

    JButton upTempo = new JButton("Tempo Up");
    upTempo.addActionListener(new MyUpTempoListener());
    buttonBox.add(upTempo);

    JButton downTempo = new JButton("Tempo Down");
    downTempo.addActionListener(new MyDownTempoListener());
    buttonBox.add(downTempo);

    Box nameBox = new Box(BoxLayout.Y_AXIS);
    for (int i = 0; i < 16; i++) {
       nameBox.add(new Label(instrumentNames[i]));
    }

    background.add(BorderLayout.EAST, buttonBox);
    background.add(BorderLayout.WEST, nameBox);

    theFrame.getContentPane().add(background);

    GridLayout grid = new GridLayout(16,16);
    grid.setVgap(1);
    grid.setHgap(2);
    mainPanel = new JPanel(grid);
    background.add(BorderLayout.CENTER, mainPanel);

    for (int i = 0; i < 256; i++) {                    
        JCheckBox c = new JCheckBox();
        c.setSelected(false);
        checkboxList.add(c);
        mainPanel.add(c);            
    } // end loop

    setUpMidi();

    theFrame.setBounds(50,50,300,300);
    theFrame.pack();
    theFrame.setVisible(true);
} // close method


public void setUpMidi() {
  try {
    sequencer = MidiSystem.getSequencer();
    sequencer.open();
    sequence = new Sequence(Sequence.PPQ,4);
    track = sequence.createTrack();
    sequencer.setTempoInBPM(120);

  } catch(Exception e) {e.printStackTrace();}
} // close method

public void buildTrackAndStart() {
  int[] trackList = null;

  sequence.deleteTrack(track);
  track = sequence.createTrack();

    for (int i = 0; i < 16; i++) {
      trackList = new int[16];

      int key = instruments[i];   

      for (int j = 0; j < 16; j++ ) {         
          JCheckBox jc = (JCheckBox) checkboxList.get(j + (16*i));
          if ( jc.isSelected()) {
             trackList[j] = key;
          } else {
             trackList[j] = 0;
          }                    
       } // close inner loop

       makeTracks(trackList);

   } // close outer


   try {
       sequencer.setSequence(sequence); 
     sequencer.setLoopCount(sequencer.LOOP_CONTINUOUSLY);                   
       sequencer.start();
       sequencer.setTempoInBPM(120);
   } catch(Exception e) {e.printStackTrace();}
} // close buildTrackAndStart method


public class MyStartListener implements ActionListener {
    public void actionPerformed(ActionEvent a) {
        buildTrackAndStart();
    }
} // close inner class

public class MyStopListener implements ActionListener {
    public void actionPerformed(ActionEvent a) {
        sequencer.stop();
    }
} // close inner class

public class MyUpTempoListener implements ActionListener {
    public void actionPerformed(ActionEvent a) {
      float tempoFactor = sequencer.getTempoFactor(); 
        sequencer.setTempoFactor((float)(tempoFactor * 1.03));
    }
 } // close inner class

 public class MyDownTempoListener implements ActionListener {
     public void actionPerformed(ActionEvent a) {
      float tempoFactor = sequencer.getTempoFactor();
        sequencer.setTempoFactor((float)(tempoFactor * .97));
    }
} // close inner class

public void makeTracks(int[] list) {        

   for (int i = 0; i < 16; i++) {
      int key = list[i];

      if (key != 0) {
         track.add(makeEvent(144,9,key, 100, i));
         track.add(makeEvent(128,9,key, 100, i+1));
      }
   }
}

public  MidiEvent makeEvent(int comd, int chan, int one, int two, int tick) {
    MidiEvent event = null;
    try {
        ShortMessage a = new ShortMessage();
        a.setMessage(comd, chan, one, two);
        event = new MidiEvent(a, tick);

    } catch(Exception e) {e.printStackTrace(); }
    return event;
}

} // close class

以上是代码，如果有人可以告诉我setMessage()如何工作，以及它的论点，那将是一个很大的帮助，因为我看到了所有的文件，但我无法理解。

Answer 1

鼓乐器形成一个特殊情况，因为它们没有像钢琴或小号那样的特定音高。特定的MIDI通道用于传输鼓乐器的播放。在General Midi，它是10频道，但你会发现可以编程的合成器可以在任何频道接收鼓。

如果分配给鼓乐器的通道（以及通常包含在合成器中的特殊音效），音高的NOTE ON和NOTE OFF信息信息实际上用于选择将播放的鼓或声音效果

例如，要在频道10上播放低音鼓乐器，请按如下方式发送NOTE ON消息：

使用通道10（编码9）写入35，这是用于上面GM列表中的原声低音鼓的音符编号。

有关详细信息，请参阅[1]：https://www.cs.cmu.edu/~music/cmsip/readings/MIDI%20tutorial%20for%20programmers.html

setMessage（）的工作原理和每一行的声音变化？

1 个答案: