Multiple Midi Channels Problem

[Panos Katertziadis]

Hello all.

I am not sure where should i post this. It may be a threading problem, or it may be a Java Sound problem, or it may be a Java bug (yeah... right).

The following lines of code aiming to use a midi synthesizer in order to have it play random notes.
If i use this code routing midi to any hardware port, it works fine.
If i use it to route midi to "Java Software Synthesizer" device, i can only use one (out of 16) midi channels of this device: should i attempt to concurrently use any second (or third) channel, the program breaks, and i am getting the following error:

"Invalid memory access of location 0x22795d32c rip=0x7fffffe00eca"

Please note the lines that start with "new Player".
Commenting all of them (except one), results in sending midi to one channel only - thus, no problem.
Un-commenting two lines, thus evoking a second "player" causes the error.

I tried it on Snow Leopard and on Windows, it gives a similar "invalid memory" error.
I fear that all this trouble has to do with my less-than-perfect knowledge on threading, so i would appreciate any help.

Kind Regards,
Panos



The code:

import java.util.*;
import javax.sound.midi.*;
 
class Tester {
   public static void main (String[] args) {
 
	// Discover Connected Midi Devices - Start
	System.out.println("\n");
	System.out.println("List Of Midi Devices Available:");
	System.out.println("-------------------------------");
  	MidiDevice.Info[] mididevices = MidiSystem.getMidiDeviceInfo();
	for (MidiDevice.Info deviceInfo : mididevices)
	{
  		System.out.println("Device Name : " + deviceInfo.getName());
  		System.out.println("Device Description : " + deviceInfo.getDescription() + "\n");
	}
	// Discover Connected Midi Devices - End
	
	    try
	    {
		MidiDevice.Info[] devices = MidiSystem.getMidiDeviceInfo();
		for (MidiDevice.Info deviceInfo : devices) {
		//System.out.println("Name : " + deviceInfo.getName());
		//System.out.println("Vendor : " + deviceInfo.getVendor());
		//System.out.println("Version : " + deviceInfo.getVersion());
	   	//System.out.println("Description : " + deviceInfo.getDescription());
		//System.out.println("\n");
		}
 
		new Player("4").start();
	    new Player("1").start();
		//new Player("2").start();
		//new Player("3").start();
		}
 
		catch (Exception e)
   	{
     		System.out.println("Something failed !!!");
   	}	
   }
}
 
class intRand {
   public static int get (int[] array) {
	Random generator = new Random();
   int rnd = generator.nextInt(array.length);
   return array[rnd];
   }
}
 
class stringRand {
   public static String get (String[] array) {
	Random generator = new Random();
   int rnd = generator.nextInt(array.length);
   return array[rnd];
   }
}
 
class Player extends Thread {
   public Player(String str) {
   super(str);
   }
   public void run() {
	String selectedChannel = getName();
		int midiChannel = Integer.parseInt(selectedChannel);
 
		try
	    {
	    MidiDevice.Info[] infos = MidiSystem.getMidiDeviceInfo();
	    int numInfos = infos.length;
	    MidiDevice.Info deviceInfo = null;
	    for (int i = 0; i < numInfos; i++)
	    {
	      if (infos[i].getName().equals("Java Sound Synthesizer")) { deviceInfo = infos[i]; }
	    }
	    MidiDevice outputDevice =
	    MidiSystem.getMidiDevice(deviceInfo);
 
	    outputDevice.open();
 
	    ShortMessage sm = new ShortMessage();
	    Receiver receiver = outputDevice.getReceiver();
 
	    int sequenceSteps 			= 200;
		int[] selectedNotes 		= { 70 , 80 , 75 , 67 , 51 };
		int[] selectedDurations 	= { 100, 300, 625, 1250, 5000 };
		int[] selectedVelocities 	= { 75 , 85 };
		int[] selectedPauses 		= { 100, 300, 625, 1250, 5000 };
 
		for (int i = 1; i < sequenceSteps+1; i++)
		{
		int n = intRand.get(selectedNotes);
		int d = intRand.get(selectedDurations);
		int v = intRand.get(selectedVelocities);
		int p = intRand.get(selectedPauses);
		
		// Report
		System.out.println("Midi : " + (midiChannel+1) + ". Step : " + i + ". Note : " + n + ". Duration : " + d + ". Velocity : " + v + ".");
 
		sm.setMessage(ShortMessage.NOTE_ON, midiChannel, n, v); receiver.send(sm, -1);
	    if (i < sequenceSteps) { Thread.sleep(d); }
		if (i == sequenceSteps) { Thread.sleep(10000); }
	    sm.setMessage(ShortMessage.NOTE_OFF, midiChannel, n, v); receiver.send(sm, -1);
		sleep(p);
		}
 
	    outputDevice.close();
	    }
	    catch (Exception e)
	    {
	      System.out.println("Something failed !!!");
	    }
   }
}

[Ankit Garg]

Protocol Webmaster please check your private messages for some administrative matter...

[Ankit Garg]

Thanks Panos for changing your display name.

Please tell when you post the same question to another site. This question has been asked here.

Anyways, I don't have any idea about this. Maybe the Java Sound Synthesizer is not multitimbral (cannot play simultaneously on multiple channels), this is all that I can predict. I found a few pages which might be helpful

MIDI FAQ
MIDI Overview

[Panos Katertziadis]

The question has also been asked at the DZone forums.
It is not answered anywhere (until now) and i will notify here if and when it does, so that no one will waste any time.

[Ankit Garg]

I played around with your program and now I'm able to generate multiple sounds simultaneously. What I did was instead of opening the MidiDevice multiple times, I opened it once and and started multiple threads send messages to that MidiDevices receiver. That is this code was run only once

MidiDevice outputDevice = MidiSystem.getMidiDevice(deviceInfo);
	 
outputDevice.open();
	 
Receiver receiver = outputDevice.getReceiver();

And then I started 4 threads to send ShortMessage to send messages to this Receiver object. Your technique called this code multiple times so maybe the second time you open the Java Sound Synthesizer device, that created problems...

[Panos Katertziadis]

I will try this very soon, and provide feedback.
Thank you for assisting.

Panos