如何从MIDI序列获取音符开/关信息？
我希望在播放MIDI序列中收到音符开/关事件的通知，以在基于屏幕的（钢琴）键盘上显示音符。
下面的代码在播放MIDI文件时添加MetaEventListener和ControllerEventListener ，但仅在轨道的开头和结尾显示一些消息。
我们怎样才能听取关于MIDI事件的注释和注释？
import java.io.File; import javax.sound.midi.*; import javax.swing.JOptionPane; class PlayMidi { public static void main(String[] args) throws Exception { /* This MIDI file can be found at.. https://drive.google.com/open?id=0B5B9wDXIGw9lR2dGX005anJsT2M&authuser=0 */ File path = new File("I:\\projects\\EverLove.mid"); Sequence sequence = MidiSystem.getSequence(path); Sequencer sequencer = MidiSystem.getSequencer(); sequencer.open(); MetaEventListener mel = new MetaEventListener() { @Override public void meta(MetaMessage meta) { final int type = meta.getType(); System.out.println("MEL - type: " + type); } }; sequencer.addMetaEventListener(mel); int[] types = new int[128]; for (int ii = 0; ii < 128; ii++) { types[ii] = ii; } ControllerEventListener cel = new ControllerEventListener() { @Override public void controlChange(ShortMessage event) { int command = event.getCommand(); if (command == ShortMessage.NOTE_ON) { System.out.println("CEL - note on!"); } else if (command == ShortMessage.NOTE_OFF) { System.out.println("CEL - note off!"); } else { System.out.println("CEL - unknown: " + command); } } }; int[] listeningTo = sequencer.addControllerEventListener(cel, types); for (int ii : listeningTo) { System.out.println("Listening To: " + ii); } sequencer.setSequence(sequence); sequencer.start(); JOptionPane.showMessageDialog(null, "Exit this dialog to end"); sequencer.stop(); sequencer.close(); } }
我会看着有没有比我提出的两个建议中的任何一个更好的答案，这些建议显然不太理想。
- 编辑midi文件以包含与现有密钥匹配的元事件
- 写你自己的事件系统
我自己也没有用MIDI做很多事情。 我偶尔会导入MIDI乐谱并删除大部分信息，将其转换为我为自己的音频需求编写的事件系统（触发我写的FM合成器）。
这是对已接受答案的第一个建议的实现。 它将显示一个选项窗格确认对话框， NOTE_ON是否添加新轨道以保存与每个现有轨道的NOTE_ON和NOTE_OFF消息相对应的元事件。
如果用户选择这样做，他们将在整个MIDI序列的播放过程中看到Meta事件。
import java.io.File; import javax.sound.midi.*; import javax.swing.JOptionPane; class PlayMidi { /** Iterates the MIDI events of the first track and if they are a * NOTE_ON or NOTE_OFF message, adds them to the second track as a * Meta event. */ public static final void addNotesToTrack( Track track, Track trk) throws InvalidMidiDataException { for (int ii = 0; ii < track.size(); ii++) { MidiEvent me = track.get(ii); MidiMessage mm = me.getMessage(); if (mm instanceof ShortMessage) { ShortMessage sm = (ShortMessage) mm; int command = sm.getCommand(); int com = -1; if (command == ShortMessage.NOTE_ON) { com = 1; } else if (command == ShortMessage.NOTE_OFF) { com = 2; } if (com > 0) { byte[] b = sm.getMessage(); int l = (b == null ? 0 : b.length); MetaMessage metaMessage = new MetaMessage(com, b, l); MidiEvent me2 = new MidiEvent(metaMessage, me.getTick()); trk.add(me2); } } } } public static void main(String[] args) throws Exception { /* This MIDI file can be found at.. https://drive.google.com/open?id=0B5B9wDXIGw9lR2dGX005anJsT2M&authuser=0 */ File path = new File("I:\\projects\\EverLove.mid"); Sequence sequence = MidiSystem.getSequence(path); Sequencer sequencer = MidiSystem.getSequencer(); sequencer.open(); MetaEventListener mel = new MetaEventListener() { @Override public void meta(MetaMessage meta) { final int type = meta.getType(); System.out.println("MEL - type: " + type); } }; sequencer.addMetaEventListener(mel); int[] types = new int[128]; for (int ii = 0; ii < 128; ii++) { types[ii] = ii; } ControllerEventListener cel = new ControllerEventListener() { @Override public void controlChange(ShortMessage event) { int command = event.getCommand(); if (command == ShortMessage.NOTE_ON) { System.out.println("CEL - note on!"); } else if (command == ShortMessage.NOTE_OFF) { System.out.println("CEL - note off!"); } else { System.out.println("CEL - unknown: " + command); } } }; int[] listeningTo = sequencer.addControllerEventListener(cel, types); StringBuilder sb = new StringBuilder(); for (int ii = 0; ii < listeningTo.length; ii++) { sb.append(ii); sb.append(", "); } System.out.println("Listenning to: " + sb.toString()); int mirror = JOptionPane.showConfirmDialog( null, "Add note on/off messages to another track as meta messages?", "Confirm Mirror", JOptionPane.OK_CANCEL_OPTION); if (mirror == JOptionPane.OK_OPTION) { Track[] tracks = sequence.getTracks(); Track trk = sequence.createTrack(); for (Track track : tracks) { addNotesToTrack(track, trk); } } sequencer.setSequence(sequence); sequencer.start(); JOptionPane.showMessageDialog(null, "Exit this dialog to end"); sequencer.stop(); sequencer.close(); } }
键盘的实现
import java.awt.*; import java.awt.event.*; import java.awt.geom.*; import javax.swing.*; import javax.swing.border.EmptyBorder; import javax.sound.midi.*; import java.util.ArrayList; import java.io.*; import java.net.URL; public class MidiPianola { private JComponent ui = null; public static final int OTHER = -1; public static final int NOTE_ON = 1; public static final int NOTE_OFF = 2; private OctaveComponent[] octaves; Sequencer sequencer; int startOctave = 0; int numOctaves = 0; MidiPianola(int startOctave, int numOctaves) throws MidiUnavailableException { this.startOctave = startOctave; this.numOctaves = numOctaves; initUI(); } public void openMidi(URL url) throws InvalidMidiDataException, IOException { openMidi(url.openStream()); } public void openMidi(InputStream is) throws InvalidMidiDataException, IOException { Sequence sequence = MidiSystem.getSequence(is); Track[] tracks = sequence.getTracks(); Track trk = sequence.createTrack(); for (Track track : tracks) { addNotesToTrack(track, trk); } sequencer.setSequence(sequence); startMidi(); } public void startMidi() { sequencer.start(); } public void stopMidi() { sequencer.stop(); } public void closeSequencer() { sequencer.close(); } private void handleNote(final int command, int note) { OctaveComponent octave = getOctaveForNote(note); PianoKey key = octave.getKeyForNote(note); if (command == NOTE_ON) { key.setPressed(true); } else if (command == NOTE_OFF) { key.setPressed(false); } ui.repaint(); } private OctaveComponent getOctaveForNote(int note) { return octaves[(note / 12) - startOctave]; } public void initUI() throws MidiUnavailableException { if (ui != null) { return; } sequencer = MidiSystem.getSequencer(); MetaEventListener mel = new MetaEventListener() { @Override public void meta(MetaMessage meta) { final int type = meta.getType(); byte b = meta.getData()[1]; int i = (int) (b & 0xFF); handleNote(type, i); } }; sequencer.addMetaEventListener(mel); sequencer.open(); ui = new JPanel(new BorderLayout(4, 4)); ui.setBorder(new EmptyBorder(4, 4, 4, 4)); JPanel keyBoard = new JPanel(new GridLayout(1, 0)); ui.add(keyBoard, BorderLayout.CENTER); int end = startOctave + numOctaves; octaves = new OctaveComponent[end - startOctave]; for (int i = startOctave; i < end; i++) { octaves[i - startOctave] = new OctaveComponent(i); keyBoard.add(octaves[i - startOctave]); } JToolBar tools = new JToolBar(); tools.setFloatable(false); ui.add(tools, BorderLayout.PAGE_START); tools.setFloatable(false); Action open = new AbstractAction("Open") { JFileChooser fileChooser = new JFileChooser(); @Override public void actionPerformed(ActionEvent e) { int result = fileChooser.showOpenDialog(ui); if (result == JFileChooser.APPROVE_OPTION) { File f = fileChooser.getSelectedFile(); try { openMidi(f.toURI().toURL()); } catch (Exception ex) { ex.printStackTrace(); } } } }; tools.add(open); Action rewind = new AbstractAction("Rewind") { @Override public void actionPerformed(ActionEvent e) { sequencer.setTickPosition(0); } }; tools.add(rewind); Action play = new AbstractAction("Play") { @Override public void actionPerformed(ActionEvent e) { startMidi(); } }; tools.add(play); Action stop = new AbstractAction("Stop") { @Override public void actionPerformed(ActionEvent e) { stopMidi(); } }; tools.add(stop); } public JComponent getUI() { return ui; } /** * Iterates the MIDI events of the first track, and if they are a NOTE_ON or * NOTE_OFF message, adds them to the second track as a Meta event. */ public static final void addNotesToTrack( Track track, Track trk) throws InvalidMidiDataException { for (int ii = 0; ii < track.size(); ii++) { MidiEvent me = track.get(ii); MidiMessage mm = me.getMessage(); if (mm instanceof ShortMessage) { ShortMessage sm = (ShortMessage) mm; int command = sm.getCommand(); int com = OTHER; if (command == ShortMessage.NOTE_ON) { com = NOTE_ON; } else if (command == ShortMessage.NOTE_OFF) { com = NOTE_OFF; } if (com > OTHER) { byte[] b = sm.getMessage(); int l = (b == null ? 0 : b.length); MetaMessage metaMessage = new MetaMessage( com, b, l); MidiEvent me2 = new MidiEvent(metaMessage, me.getTick()); trk.add(me2); } } } } public static void main(String[] args) { Runnable r = new Runnable() { @Override public void run() { try { try { UIManager.setLookAndFeel( UIManager.getSystemLookAndFeelClassName()); } catch (Exception useDefault) { } SpinnerNumberModel startModel = new SpinnerNumberModel(2,0,6,1); JOptionPane.showMessageDialog( null, new JSpinner(startModel), "Start Octave", JOptionPane.QUESTION_MESSAGE); SpinnerNumberModel octavesModel = new SpinnerNumberModel(5,5,11,1); JOptionPane.showMessageDialog( null, new JSpinner(octavesModel), "Number of Octaves", JOptionPane.QUESTION_MESSAGE); final MidiPianola o = new MidiPianola( startModel.getNumber().intValue(), octavesModel.getNumber().intValue()); WindowListener closeListener = new WindowAdapter() { @Override public void windowClosing(WindowEvent e) { o.closeSequencer(); } }; JFrame f = new JFrame("MIDI Pianola"); f.addWindowListener(closeListener); f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE); f.setLocationByPlatform(true); f.setContentPane(o.getUI()); f.setResizable(false); f.pack(); f.setVisible(true); } catch (MidiUnavailableException ex) { ex.printStackTrace(); } catch (InvalidMidiDataException ex) { ex.printStackTrace(); } catch (IOException ex) { ex.printStackTrace(); } } }; SwingUtilities.invokeLater(r); } } class OctaveComponent extends JPanel { int octave; ArrayList keys; PianoKey selectedKey = null; public OctaveComponent(int octave) { this.octave = octave; init(); } public PianoKey getKeyForNote(int note) { int number = note % 12; return keys.get(number); } @Override public void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; for (PianoKey key : keys) { key.draw(g2); } } public static final Shape removeArrayFromShape(Shape shape, Shape[] shapes) { Area a = new Area(shape); for (Shape sh : shapes) { a.subtract(new Area(sh)); } return a; } public final Shape getEntireBounds() { Area a = new Area(); for (PianoKey key : keys) { a.add(new Area(key.keyShape)); } return a; } @Override public Dimension getPreferredSize() { Shape sh = getEntireBounds(); Rectangle r = sh.getBounds(); Dimension d = new Dimension(rx + r.width, ry + r.height + 1); return d; } public void init() { keys = new ArrayList (); int w = 30; int h = 200; int x = 0; int y = 0; int xs = w - (w / 3); Shape[] sharps = new Shape[5]; int hs = h * 3 / 5; int ws = w * 2 / 3; sharps[0] = new Rectangle2D.Double(xs, y, ws, hs); xs += w; sharps[1] = new Rectangle2D.Double(xs, y, ws, hs); xs += 2 * w; sharps[2] = new Rectangle2D.Double(xs, y, ws, hs); xs += w; sharps[3] = new Rectangle2D.Double(xs, y, ws, hs); xs += w; sharps[4] = new Rectangle2D.Double(xs, y, ws, hs); Shape[] standards = new Shape[7]; for (int ii = 0; ii < standards.length; ii++) { Shape shape = new Rectangle2D.Double(x, y, w, h); x += w; standards[ii] = removeArrayFromShape(shape, sharps); } int note = 0; int ist = 0; int ish = 0; keys.add(new PianoKey(standards[ist++], (octave * 12) + note++, "C", this)); keys.add(new PianoKey(sharps[ish++], (octave * 12) + note++, "C#", this)); keys.add(new PianoKey(standards[ist++], (octave * 12) + note++, "D", this)); keys.add(new PianoKey(sharps[ish++], (octave * 12) + note++, "D#", this)); keys.add(new PianoKey(standards[ist++], (octave * 12) + note++, "E", this)); keys.add(new PianoKey(standards[ist++], (octave * 12) + note++, "F", this)); keys.add(new PianoKey(sharps[ish++], (octave * 12) + note++, "F#", this)); keys.add(new PianoKey(standards[ist++], (octave * 12) + note++, "G", this)); keys.add(new PianoKey(sharps[ish++], (octave * 12) + note++, "G#", this)); keys.add(new PianoKey(standards[ist++], (octave * 12) + note++, "A", this)); keys.add(new PianoKey(sharps[ish++], (octave * 12) + note++, "A#", this)); keys.add(new PianoKey(standards[ist++], (octave * 12) + note++, "B", this)); } } class PianoKey { Shape keyShape; int number; String name; Component component; boolean pressed = false; PianoKey(Shape keyShape, int number, String name, Component component) { this.keyShape = keyShape; this.number = number; this.name = name; this.component = component; } public void draw(Graphics2D g) { if (name.endsWith("#")) { g.setColor(Color.BLACK); } else { g.setColor(Color.WHITE); } g.fill(keyShape); g.setColor(Color.GRAY); g.draw(keyShape); if (pressed) { Rectangle r = keyShape.getBounds(); GradientPaint gp = new GradientPaint( rx, ry, new Color(255, 225, 0, 40), rx, ry + (int) r.getHeight(), new Color(255, 225, 0, 188)); g.setPaint(gp); g.fill(keyShape); g.setColor(Color.GRAY); g.draw(keyShape); } } public boolean isPressed() { return pressed; } public void setPressed(boolean pressed) { this.pressed = pressed; } }