读取Java中的MIDI文件

Question

我正在尝试将.MID文件读入Java程序，并希望将每个音符/和弦分开，以便在某种UI上显示它们。我在Java中使用Sequencer
API的运气并不好，尝试直接使用MidiFileReader也不适合我。如果有人想看的话，我将附上我在这里使用的代码：

package miditest;
import java.io.File;
import java.io.IOException;
import javax.sound.midi.InvalidMidiDataException;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.MidiUnavailableException;
import javax.sound.midi.Sequence;
import javax.sound.midi.Sequencer;

public class Main {
    public static void main(String[] args) throws InvalidMidiDataException, IOException, MidiUnavailableException{
    Sequence sequence = MidiSystem.getSequence(new File("test.mid"));

    // Create a sequencer for the sequence
    Sequencer sequencer = MidiSystem.getSequencer();
    sequencer.open();
    sequencer.setSequence(sequence);

    // Start playing
    sequencer.start();
    }
}

Answer 1

我从来没有深入研究过Java对MIDI的支持，而上一次我认真地进行MIDI编程是在Commodore Amiga成为国王的时候。

看来您可能需要做大量的手动工作。这是一个粗略的示例，可解释所有NOTE_ON和NOTE_OFF事件，对于其余事件，它仅显示命令号。

之所以看起来比最初想像的要复杂，是因为MIDI专注于捕获乐器事件（例如，何时按下键盘琴键，何时释放琴键等等），而不是在乐谱符号上。

该代码为每个事件打印出一行，并标明刻度线（这是事件的计时信息），通道，事件类型，音符名称，键，力度

import java.io.File;

import javax.sound.midi.MidiEvent;
import javax.sound.midi.MidiMessage;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.Sequence;
import javax.sound.midi.ShortMessage;
import javax.sound.midi.Track;

public class Test {
    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"};

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

        int trackNumber = 0;
        for (Track track :  sequence.getTracks()) {
            trackNumber++;
            System.out.println("Track " + trackNumber + ": size = " + track.size());
            System.out.println();
            for (int i=0; i < track.size(); i++) { 
                MidiEvent event = track.get(i);
                System.out.print("@" + event.getTick() + " ");
                MidiMessage message = event.getMessage();
                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());
                }
            }

            System.out.println();
        }

    }
}

例如，我躺在这里的毛皮elise.mid在开始时会产生类似以下的内容：

@0 Channel: 1 Note on, E5 key=76 velocity: 127
@192 Channel: 1 Note off, E5 key=76 velocity: 64
@192 Channel: 1 Note on, D#5 key=75 velocity: 127
@384 Channel: 1 Note off, D#5 key=75 velocity: 64
@384 Channel: 1 Note on, E5 key=76 velocity: 127
@576 Channel: 1 Note off, E5 key=76 velocity: 64
@576 Channel: 1 Note on, D#5 key=75 velocity: 127
@768 Channel: 1 Note off, D#5 key=75 velocity: 64
@768 Channel: 1 Note on, E5 key=76 velocity: 127
@960 Channel: 1 Note off, E5 key=76 velocity: 64
@960 Channel: 1 Note on, B4 key=71 velocity: 127
@1152 Channel: 1 Note off, B4 key=71 velocity: 64
@1152 Channel: 1 Note on, D5 key=74 velocity: 127
@1344 Channel: 1 Note off, D5 key=74 velocity: 64
@1344 Channel: 1 Note on, C5 key=72 velocity: 127
@1536 Channel: 1 Note off, C5 key=72 velocity: 64
@1536 Channel: 1 Note on, A4 key=69 velocity: 127
@1920 Channel: 1 Note off, A4 key=69 velocity: 64

更新：通道是MIDI规范的16个通道。

http://www.midi.org/techspecs/gm.php

通道：支持所有16个MIDI通道。每个通道可以播放可变数量的声音（复音）。每个通道可以演奏不同的乐器（声音/音色/音色）。基于键的打击乐始终在MIDI通道10上。

速度是用于控制声音的属性之一。例如，在键盘上捕获MIDI数据就是您按下琴键的力量。通常，它控制声音的音量。详情请参阅这里：http :
//audio.tutsplus.com/tutorials/production/7-ways-to-use-and-edit-midi-
velocity/