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Loading midi files? (Read 1417 times)

combatdave YaBB Newbies Offline Posts: 26	Loading midi files? Nov 18^th, 2008, 12:27am Is this possible at all? I'm essentially making a Guitar Hero clone, and using midi to store the fret data seems like the most logical approach... but can it be done? Cheers

combatdave

Re: Loading midi files?
Reply #1 - Nov 18^th, 2008, 1:04am

So I did a little bit of Java digging, and got together what I thought should be loading a midi file:

import java.io.File;
import javax.sound.midi.MidiDevice;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.MidiUnavailableException;
import javax.sound.midi.Sequence;

MidiSystem midiSystem;

void setup(){
size(128*5,128*5);
smooth();
background(0);

File midiFile = new File("MidiTest.mid");

println(midiFile);

Sequence midiSequence = midiSystem.getSequence(midiFile);

}

The file is just a simple 1 bar midi file with one note made in Ableton Live. When I run it, though, I get an "Unhandled exception type InvalidMidiDataException". From the java docs, apparently this means:

This operation can only succeed for files of a type which can be parsed by an installed file reader. It may fail with an InvalidMidiDataException even for valid files if no compatible file reader is installed. It will also fail with an InvalidMidiDataException if a compatible file reader is installed, but encounters errors while constructing the Sequence object from the file data.

So whats going wrong, and how do I fix this?

I'm on OSX 10.5

combatdave

Re: Loading midi files?
Reply #2 - Nov 18^th, 2008, 2:45pm

Heres a function I created last night which will load a midi file and return back an ArrayList of notes + their times.

ArrayList loadMidi(String fileName)
{

String sketchPath = this.sketchPath;
println(sketchPath);

File midiFile = new File(sketchPath + "/" + fileName);

println(midiFile.getAbsolutePath());

if(!midiFile.exists() || midiFile.isDirectory() || !midiFile.canRead())
{
println("Error reading file");
}

Sequence midiSequence = null;

try
{
midiSequence = midiSystem.getSequence(midiFile);
}
catch (Exception e)
{
e.printStackTrace();
}

if (midiSequence == null)
{
return null;
}

try
{
midiSequencer = midiSystem.getSequencer();
}
catch (Exception e)
{
println(e);
}

try
{
midiSequencer.setSequence(midiSequence);
}
catch (Exception e)
{
e.printStackTrace();
}

Track[] midiTracks = midiSequence.getTracks();

//println("num tracks: " + midiTracks.length);

Track midiTrack = midiTracks[0];

int iNumEvents = midiTrack.size();

//println("num events: " + iNumEvents);

ArrayList myNotes = new ArrayList();

for (int i=0; i<iNumEvents; i++)
{
MidiEvent event = midiTrack.get(i);

MidiMessage message = event.getMessage();

if (message.getLength()-1 == 2) //message length - staus byte = 2 (short message)
{

int iMessage = (int)(message.getMessage()[0] & 0xFF);

if (iMessage == ShortMessage.NOTE_ON)
{
int iFullNote = (int)(message.getMessage()[1] & 0xFF);

int iNote = iFullNote % 12;
int iOctave = floor(iFullNote/12) - 2;

float fBPS = 132.0 / 60.0;
float fSPB = 1.0 / fBPS;

float fTime = event.getTick() * fSPB / 96;

//println("Note On: " + Notes[iNote] + "-" + iOctave + " @" + fTime);

Note n = new Note();
n.m_sNote = Notes[iNote];
n.m_fTime = fTime;
myNotes.add(n);

//384 ticks per bar?
}
}
}

return myNotes;

}

dihardja Ex Member	Re: Loading midi files? Reply #3 - Nov 18^th, 2008, 6:04pm nice work, but you miss one thing, the duration of the note .

combatdave YaBB Newbies Offline Posts: 26	Re: Loading midi files? Reply #4 - Nov 19^th, 2008, 3:43pm didn't need it so i left it out maybe it would be nice to have, though.

klauslukas YaBB Newbies Offline Posts: 11	Re: Loading midi files? Reply #5 - Nov 21^st, 2008, 6:14pm Hey that is exactly what I was looking for. But I tried to use your function but it doesn't work :( it doesn't find a midiSequencer variable, and it doesn't recognize the "Note" and the shortMessage :/

combatdave

Re: Loading midi files?
Reply #6 - Nov 22^nd, 2008, 8:59pm

oops my appologies... heres the correct stuff

Code:



import javax.sound.midi.Sequencer;
import javax.sound.midi.MidiDevice;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.MidiEvent;
import javax.sound.midi.MidiMessage;
import javax.sound.midi.MidiUnavailableException;
import javax.sound.midi.InvalidMidiDataException;
import java.io.IOException;
import javax.sound.midi.Sequence;
import javax.sound.midi.Track;
import javax.sound.midi.ShortMessage;

MidiSystem midiSystem;
Sequencer midiSequencer;

String[] Notes = {"C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B"};

class Note
{
  float m_fTime;
  String m_sNote;
}



class Song
{
  
  Song(String sName)
  {
    m_sName = sName;
  }
  
  String m_sName = "";
  ArrayList m_Notes = new ArrayList();
}



int g_iTicksPerBeat = 96;

ArrayList loadMidi(String fileName, float fBPM)
{
  
  String sketchPath = this.sketchPath;
  println(sketchPath);
  
  File midiFile = new File(sketchPath + "/" + fileName);
  
  println(midiFile.getAbsolutePath());
  
  if(!midiFile.exists() || midiFile.isDirectory() || !midiFile.canRead())
  {
    println("Error reading file");
  }
  
  Sequence midiSequence = null;
 
  try
  {
    midiSequence = midiSystem.getSequence(midiFile);
  }
  catch (Exception e)
  {
    e.printStackTrace();
  }
  
  if (midiSequence == null)
  {
    return null;
  }

  
  Track[] midiTracks = midiSequence.getTracks();  
  Track midiTrack = midiTracks[0];
  
  int iNumEvents = midiTrack.size();
  
  ArrayList myNotes = new ArrayList();
  
  for (int i=0; i<iNumEvents; i++)
  {
    MidiEvent event = midiTrack.get(i);
    
    MidiMessage message = event.getMessage();
    
    if (message.getLength()-1 == 2) //message length - staus byte = 2 (short message)
    {
	
	int iMessage = (int)(message.getMessage()[0] & 0xFF);
	
	if (iMessage == ShortMessage.NOTE_ON)
	{	  
	  int iFullNote = (int)(message.getMessage()[1] & 0xFF);
	  
	  int iNote = iFullNote % 12;
	  int iOctave = floor(iFullNote/12) - 2;
	  
	  float fBPS = fBPM / 60.0;
	  float fSPB = 1.0 / fBPS;
	  
	  float fTime = event.getTick() * fSPB / g_iTicksPerBeat;
	  
	  //println("Note On: " + Notes[iNote] + "-" + iOctave + " @" + fTime + "[" + event.getTick() + "]");
	  
	  Note n = new Note();
	  n.m_sNote = Notes[iNote];
	  n.m_fTime = fTime;
	  myNotes.add(n);
	  
	  //384 ticks per bar?
	}
    }
  }
  
  return myNotes;
  
}

that *should* work, let me know if it doesn't.

klauslukas

Re: Loading midi files?
Reply #7 - Nov 22^nd, 2008, 11:37pm

Oh thanks for posting that !
I just tried, and it doesn't show error messages anymore :)
But the arrayList it returns is empty :(

I tried with this file, misery.mid ("http://rock.mididb.com/beatles/")
and it returns me nothing but "[]"
I took a look and saw that the iMessage variable is always set to 255 and never 144 (ShortMessage.NOTE_ON) so it doesn't happen anything
for this .mid, the Track length is 12 and size is 7.
So I'm a bit lost. I think I have to understand really what is a track and all that...
But thank you for your code, and if have any idea.. ;)

klauslukas

Re: Loading midi files?
Reply #8 - Nov 22^nd, 2008, 11:49pm

OK I don't understand why but I seems to work now !

I just changed this :
Track midiTrack = midiTracks[0];

to

Track midiTrack = midiTracks[1];

and delete :

if (message.getLength()-1 == 2)
//message length - staus byte = 2 (short message)
{
}

I don't understand why you wrote this condition and what is a staus byte.
But now it returns me data like that :

...
Note On: E-3 @32.4[5184]
Note On: B-3 @33.000004[5280]
Note On: G#-3 @33.000004[5280]
Note On: E-3 @33.000004[5280]
Note On: E-4 @33.600002[5376]
Note On: B-3 @33.600002[5376]
...

So it looks okay (even if I'm not sure ;)
thanks again.

combatdave

Re: Loading midi files?
Reply #9 - Nov 22^nd, 2008, 11:55pm

the condition is to check if its a short midi message (ie one with only three bytes). i was working from some midi specification i found online, which basically said a short midi message has one status byte and two message bytes.

that statement was just ensuring it was definitely a short message that was getting looked at.

is it needed? im not sure. im no midi expert, and i was really just aiming to get some code together that worked without any intentions of sharing it (hence the messyness!)

i'm suprised that midi file loading hasnt been included in a library. weird.

klauslukas YaBB Newbies Offline Posts: 11	Re: Loading midi files? Reply #10 - Nov 23^rd, 2008, 12:46am yes it is ! Your code will be very useful, thank you very much :)

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