Java midi 音量控制不起作用

Question

很长一段时间以来，我一直在尝试让 Midi 音量控制在 MidiPlayer 类中工作。我已经在 stackoverflow 和整个 Internet 上搜索了完成此操作的示例，但我尝试过的任何操作似乎都不起作用。音量保持不变!它没有像我希望的那样改变。

我在 Windows 7 专业版上运行 Java 1.6.0_32。

这里!拥有 SSCCE:

  import java.io.*;
  import javax.sound.midi.*;
  import java.net.URL;

  public class MidiSSCCE {
     public static void main(String[] args)
     {
        // creates the midi player and sets up its sequencer and synthesizer.
        MidiPlayer midiP = new MidiPlayer();    
        double volume = 1.0;

        // loads a midi from a url into the sequencer, but doesn't start playing it yet.
        midiP.load("http://www.vgmusic.com/music/computer/microsoft/windows/touhou_6_stage3_boss.mid",true);

        // set the midi to loop indefinitely.
        midiP.loop(-1);

        // start playing the midi.
        midiP.play(true);

        // while loop changes the volume of the midi while it is playing.
        while(true) {
           midiP.setVolume(volume);
           try { Thread.sleep(300); } catch(Exception e) {}
           volume -= 0.1;
           if(volume < 0) volume += 1.0;
        }
     }
  }

  /**
  * MidiPlayer
  * author: Stephen Lindberg
  * Last modified: Oct 14, 2011
  * 
  * A class that allows midi files to be loaded and played.
  **/

  class MidiPlayer {
     private Sequence seq;
     private Sequencer seqr;
     private Synthesizer synth;
     private Receiver receiver;
     private File midiFile;
     private String midiID;
     private boolean loaded;
     private boolean usingHardwareSoundbank;

     // CONSTRUCTORS

     public MidiPlayer() {
        loaded = false;
        try  {
           // obtain the sequencer and synthesizer.
           seqr = MidiSystem.getSequencer();
           synth = MidiSystem.getSynthesizer();

           // print the user's midi device info
           System.out.println("Setting up Midi Player...");
           System.out.println("MidiDeviceInfo: ");
           for(MidiDevice.Info info : MidiSystem.getMidiDeviceInfo()) {
              System.out.println("\t" + info.getName() + ": " +info.getDescription());
           }
           System.out.println();

           // obtain the soundbank and receiver.
           Soundbank soundbank = synth.getDefaultSoundbank();
           if(soundbank == null) {
              receiver = MidiSystem.getReceiver();
              usingHardwareSoundbank = true;
              System.out.println("using hardware soundbank");
           }
           else {
              synth.loadAllInstruments(soundbank);
              receiver = synth.getReceiver();
              usingHardwareSoundbank = false;
              System.out.println("using default software soundbank:" + soundbank);
           }
           seqr.getTransmitter().setReceiver(receiver);
        }
        catch(Exception e) {
           System.out.println("MIDI error: I just don't know what went wrong! 6_9");
        }
     }


     // DATA METHODS

     /**
     *  load(String fileName)
     *  loads a midi file into this MidiPlayer.
     *  Preconditions: fileName is the name of the midi file to be loaded.
     *  Postconditions: fileName is loaded and is ready to be played.
     **/

     public void load(String fileName, boolean isOnline) {
        this.unload();
        try {
           URL midiURL;
           if(isOnline) midiURL = new URL(fileName);
           else midiURL =  getClass().getClassLoader().getResource(fileName);

           seq = MidiSystem.getSequence(midiURL);

           seqr.open();
           synth.open();

           // load our sequence into the sequencer.

           seqr.setSequence(seq);
           loaded = true;
        }
        catch(IOException ioe) {
           System.out.println("MIDI error: Problem occured while reading " + midiFile.getName() + ".");
        }
        catch(InvalidMidiDataException imde)  {
           System.out.println("MIDI error: " + midiFile.getName() + " is not a valid MIDI file or is unreadable.");
        }
        catch(Exception e)  {
           System.out.println("MIDI error: I just don't know what went wrong! 6_9");
        }
     }

     /**
     *  unload()
     *  Unloads the current midi from the MidiPlayer and releases its resources from memory.
     **/

     public void unload() {
        this.stop();
        seqr.close();
        synth.close();
        midiFile = null;
        loaded = false;
     }

     // OTHER METHODS


     /**
     *  play(boolean reset)
     *  plays the currently loaded midi.
     *  Preconditions: reset tells our midi whether or nor to begin playing from the start of the midi file's current loop start point.
     *  Postconditions: If reset is true, then the loaded midi begins playing from its loop start point (default 0). 
     *      If reset is false, then the loaded midi resumes playing from its current position.
     **/

     public void play(boolean reset) {
        if(reset)   seqr.setTickPosition(seqr.getLoopStartPoint());
        seqr.start();
     }

     /**
     *  stop()
     *  Pauses the current midi if it was playing.
     **/

     public void stop() {
        if(seqr.isOpen())   seqr.stop();
     }

     /**
     *  isRunning()
     *  Returns true if the current midi is playing. Returns false otherwise.
     **/

     public boolean isRunning() {
        return seqr.isRunning();
     }





     /**
     *  loop(int times)
     *  Sets the current midi to loop from start to finish a specific number of times.
     *  Preconditions: times is the number of times we want our midi to loop.
     *  Postconditions: The current midi is set to loop times times. 
     *      If times = -1, the current midi will be set to loop infinitely.
     **/

     public void loop(int times)
     {
        loop(times,0,-1);
     }

     /**
     *  loop(int times)
     *  Sets the current midi to loop from a specified start point to a specified end point a specific number of times.
     *  Preconditions: times is the number of times we want our midi to loop.
     *      start is our loop's start point in ticks.
     *      end is our loop's end point in ticks.
     *  Postconditions: The current midi is set to loop from tick start to tick end times times. 
     *      If times = -1, the current midi will be set to loop infinitely.
     **/

     public void loop(int times, long start, long end) {
        if(start < 0)   start = 0;
        if(end > seqr.getSequence().getTickLength() || end <= 0)   end = seqr.getSequence().getTickLength();

        if(start >= end && end != -1)   start = end-1;

        seqr.setLoopStartPoint(start);
        seqr.setLoopEndPoint(end);

        if(times == -1)   seqr.setLoopCount(Sequencer.LOOP_CONTINUOUSLY);
        else   seqr.setLoopCount(times);

     }




     public void setVolume(double vol) {
        System.out.println("Midi volume change request: " + vol);

        try {
           if(usingHardwareSoundbank) {
              ShortMessage volumeMessage = new ShortMessage();
              for ( int i = 0; i < 16; i++ ) {
                 volumeMessage.setMessage( ShortMessage.CONTROL_CHANGE, i, 7, (int)(vol*127) );
                 receiver.send( volumeMessage, -1 );
              }
           }
           else {
              MidiChannel[] channels = synth.getChannels();

              for( int c = 0; c < channels.length; c++ ) {
                 if(channels[c] != null)   channels[c].controlChange( 7, (int)( vol*127) );
              }
           }
        } 
        catch ( Exception e ) {
           e.printStackTrace();
        }
     }

  }

我尝试了以下来源的示例但没有成功:

http://www.java2s.com/Code/Java/Development-Class/SettingtheVolumeofPlayingMidiAudio.htm

How to controll the MIDI channel's volume

https://forums.oracle.com/forums/thread.jspa?messageID=5389030

MIDI Song with CC

http://www.codezealot.org/archives/27

http://www.exampledepot.com/egs/javax.sound.midi/Volume.html

Answer 1

我一直在努力解决这些关于控制声音的问题，我找到了一个代码来改变有效的音量。不幸的是，我无法理解它，但是您的代码中有些东西与我所看到的不同。也许它可以帮助你。换行试试

seqr = MidiSystem.getSequencer();

对于

seqr = MidiSystem.getSequencer(false);

也许它对你有帮助，我相信使用“false”音序器将连接到接收器，而不是合成器，然后当你将消息发送到接收器以设置音量时它会起作用。