How to measure the Frequency/Pitch/Note of a Midi File?

[Sj Balatan]

Hi guys,

I am new in this forum, actually this is my first post. I am also a relatively new java programmer, i just learned to use the language weeks ago. So forgive if i say something totally nonsense. ^^

Well, here is my problem:

i've created a midi player program. And i need to measure (any units of measurement will do) the notes being played in the midi file.. does anyone know how to do this?

thanks a lot, in advance!

[David Newton]

It's a MIDI file: there's nothing to "measure."

http://tomscarff.110mb.com/midi_analyser/midi_note_frequency.htm

[Sj Balatan]

hi david,

im not really sure what you mean by there's nothing to measure in a midi.

well, can i have a sample code, where i can get the value of the midi notes from the file.

[David Newton]

I mean the note value is contained in the note messages, it's not like you have to run a fourier analysis to figure out what notes are playing.

Have you looked through the Java MIDI tutorials, where you'd find things like javax.sound.midi.spi.MidiFileReader, javax.sound.midi.Sequence, javax.sound.midi.Track, and javax.sound.midi.MidiEvent?

I'd probably also search around to see if someone else has already written utilities to wrap all this up--I don't know what you're actually trying to do, but it seems pretty common.

[Sj Balatan]

Here is what i'm trying to do. I am a college student, and I need to finish this program in order for me to graduate.

My program should be able to:
a. have basic functionality of a midi player (play, pause, stop, file open, volume etc)
b. measure the pitch (frequency) of a singer using a mic in real time.
c. adjust the song(midi) pitch, and align it to the pitch of the singer.

I've already finished A, B. Im just having a hard time figuring out C. I need to know the pitch of the song in real time, and adjust accordingly. I getting confused on how to use note messages (maybe because of lack of sleep ).

thanks david, I appreciate that someone is actually talking to a newbie like me.

[David Newton]

You probably mean the key of a song, then, not the pitch--a song doesn't have a pitch, a note does. I question what this would actually mean, however, since changing the key of a song throughout the song would make it really, really suck. A lot. That's why there are autotuners, that correct the pitch of the *singer*, and try to align it to the expected notes of the song.

Doing it the other way around seems... like something used as a torture device on anyone that can hear tones.

[Sj Balatan]

i can't do it the other way around, because i already passed a proposal to my adviser(and i cant change it now, whether the results will be good or bad)

im planning to use pitchBend() on each channel of the Midi in changing the pitch..

can you teach me how to use midi notes, or just how to get the pitch of each notes of the midi song..?

[Mike Simmons]

Sj Balatan wrote:b. measure the pitch (frequency) of a singer using a mic in real time.

This part suggests that yes, you do really mean pitch rather than key. But it's important to note that this part would have nothing to do with a midi file, at this point. You're talking about looking at the raw wave output and determining the dominant frequency associated with it. This would probably involve a Fourier transform and finding a maximum. But I share David's skepticism here - this sounds like a bad idea. If a singer is out of tune, is it better to fix the orchestra, or fix the singer? Maybe if the singer is consitently out of tune, the latter might work, sort of. But I think most out-of-tune singers will probably be out-of-tune by an inconsistent amount. So if you "fix" the orchestra to match them, the end result will just... how should I say this?... suck. Badly.

[Sj Balatan]

Hi mike,

I already done with B. part. I can now actually measure the frequency of the singer using a mic. and yes, it has nothing to with midi.

i agree with you both guys, that It is indeed a bad idea, and it is better if i do it the other way around. But this is what my adviser suggested me to do, it doesn't matter much if it will turn out good or bad. I only need a conclusion with this study, i need to stick with it till the end..

[Mike Simmons]

OK. So you've got a singer, and you know how to determine the frequency they are singing at, at any particular point in time. And you've got a MIDI file of music intended to accompany them. And you want to make these match up, by altering the accompanying music, rather than altering the singer. OK.

Important questions: does the MIDI file also contain the notes that the singer is trying to sing? And can these notes be identified and distinguished from the other notes?

[Sj Balatan]

OK. So you've got a singer, and you know how to determine the frequency they are singing at, at any particular point in time. And you've got a MIDI file of music intended to accompany them. And you want to make these match up, by altering the accompanying music, rather than altering the singer. OK.

yes, exactly.

Important questions: does the MIDI file also contain the notes that the singer is trying to sing? And can these notes be identified and distinguished from the other notes?

that's one of my main problem, i can't get the notes of the midi file.

[David Newton]

What code do you have so far? The classes I listed above are the classes you need, although you'll also need to track song position in real-time in order to insert the MIDI messages.

[Sj Balatan]

   
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import javax.sound.midi.*;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class SoundPlayer extends JComponent {
  boolean midi; // Are we playing a midi file or a sampled one?

  Sequence sequence; // The contents of a MIDI file
  Sequencer sequencer; // We play MIDI Sequences with a Sequencer
  boolean playing = false; // whether the sound is current playing

  // Length and position of the sound are measured in milliseconds for
  // sampled sounds and MIDI "ticks" for MIDI sounds
  int audioLength; // Length of the sound.
  int audioPosition = 0; // Current position within the sound

  // The following fields are for the GUI
  JButton play; // The Play/Stop button
  JSlider progress; // Shows and sets current position in sound
  JLabel time; // Displays audioPosition as a number
  Timer timer; // Updates slider every 100 milliseconds

  // The main method just creates an SoundPlayer in a Frame and displays it
  public static void main(String[] args) throws IOException, MidiUnavailableException, InvalidMidiDataException {
    SoundPlayer player;

    File file = new File("C:\\Users\\sj\\Documents\\All Out of Love.mid"); // This is the file we'll be playing
    // Determine whether it is midi or sampled audio
    boolean ismidi;
    try {
      // We discard the return value of this method; we just need to know
      // whether it returns successfully or throws an exception
      MidiSystem.getMidiFileFormat(file);
      ismidi = true;
    } catch (InvalidMidiDataException e) {
      ismidi = false;
    }

    // Create a SoundPlayer object to play the sound.
    player = new SoundPlayer(file, ismidi);

    // Put it in a window and play it
    JFrame f = new JFrame("SoundPlayer");
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.getContentPane().add(player, "Center");
    f.pack();
    f.setVisible(true);
  }

  // Create an SoundPlayer component for the specified file.
  public SoundPlayer(File f, boolean isMidi) throws IOException, MidiUnavailableException, InvalidMidiDataException {
    if (isMidi) { // The file is a MIDI file
      midi = true;
      // First, get a Sequencer to play sequences of MIDI events
      // That is, to send events to a Synthesizer at the right time.
      sequencer = MidiSystem.getSequencer(); // Used to play sequences
      sequencer.open(); // Turn it on.

      // Get a Synthesizer for the Sequencer to send notes to
      Synthesizer synth = MidiSystem.getSynthesizer();
      synth.open(); // acquire whatever resources it needs

      // The Sequencer obtained above may be connected to a Synthesizer
      // by default, or it may not. Therefore, we explicitly connect it.
      Transmitter transmitter = sequencer.getTransmitter();
      Receiver receiver = synth.getReceiver();
      transmitter.setReceiver(receiver);

      // Read the sequence from the file and tell the sequencer about it
      sequence = MidiSystem.getSequence(f);
      sequencer.setSequence(sequence);
      audioLength = (int) sequence.getTickLength(); // Get sequence length
    } 

    // Now create the basic GUI
    play = new JButton("Play"); // Play/stop button
    progress = new JSlider(0, audioLength, 0); // Shows position in sound
    time = new JLabel("0"); // Shows position as a #

    // When clicked, start or stop playing the sound
    play.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        if (playing)
          stop();
        else
          play();
      }
    });

    // Whenever the slider value changes, first update the time label.
    // Next, if we're not already at the new position, skip to it.
    progress.addChangeListener(new ChangeListener() {
      public void stateChanged(ChangeEvent e) {
        int value = progress.getValue();
        // Update the time label
        if (midi)
          time.setText(value + "");       
        // If we're not already there, skip there.
        if (value != audioPosition)
          skip(value);
      }
    });

    // This timer calls the tick() method 10 times a second to keep
    // our slider in sync with the music.
    timer = new javax.swing.Timer(100, new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        tick();
      }
    });

    // put those controls in a row
    Box row = Box.createHorizontalBox();
    row.add(play);
    row.add(progress);
    row.add(time);

    // And add them to this component.
    setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
    this.add(row);

    // Now add additional controls based on the type of the sound

  }

  /** Start playing the sound at the current position */
  public void play() {
    if (midi)
      sequencer.start();

    timer.start();
    play.setText("Stop");
    playing = true;
  }

  /** Stop playing the sound, but retain the current position */
  public void stop() {
    timer.stop();
    if (midi)
      sequencer.stop();

    play.setText("Play");
    playing = false;
  }

  /** Stop playing the sound and reset the position to 0 */
  public void reset() {
    stop();
    if (midi)
      sequencer.setTickPosition(0);

    audioPosition = 0;
    progress.setValue(0);
  }

  /** Skip to the specified position */
  public void skip(int position) { // Called when user drags the slider
    if (position < 0 || position > audioLength)
      return;
    audioPosition = position;
    if (midi)
      sequencer.setTickPosition(position);

    progress.setValue(position); // in case skip() is called from outside
  }

  /** Return the length of the sound in ms or ticks */
  public int getLength() {
    return audioLength;
  }

  // An internal method that updates the progress bar.
  // The Timer object calls it 10 times a second.
  // If the sound has finished, it resets to the beginning
  void tick() {
    if (midi && sequencer.isRunning()) {
      audioPosition = (int) sequencer.getTickPosition();
      progress.setValue(audioPosition);
    }  else
      reset();
  }

} 

basically, this the backbone of my midi player.. hope this will get you a glimpse of my project.