USING JMF

USING JMF

SOUND & MULTI-MEDIA

IN JAVA PROGRAMS

R.S.Ramaswamy

(rs.ramaswamy@gmail.com)

--------------------------

In this brief tutorial, the author deals with the method of playing audio files in stand-alone programs and also using JMF to play audio and audio-video files.

Prior to JDK1.2, it was not possible to play audio files in stand-alone Java programs. From JDK1.2 upwards, a simple method for playing audio files in such applications, was devised. Actually, the code is very simple and can be tested in a console program itself as given below.

============================================

// audio.java

import java.applet.*;

import java.net.*;

class audio

{

public static void main(String args[])

{

try

{

URL url = new URL(args[0]);

Applet.newAudioClip(url).play();

}

catch(Exception e1)

{ System.out.println(""+e1);}

}

===========================================

We can test various types of audio files by running this program with appropriate argument.

set path=c:\windows\command;d:\jdk1.3\bin

>javac audio.java

>java audio "file:/c:/spacemusic.au"

(It is assumed that we have placed all the audio files in C drive).

Hit control & c to exit.

Similarly, we can play midi file, aif file and wav file.

Samples have been given as:

a) flutemusic.aif

b) cardring.wav

c) trips.mid

d) spacemusic.au

===========================================

For such readers who prefer to have a gui for the above program, it is given below. The code should be self-explanatory.

==============================

// tunes.java

import java.awt.*;

import java.awt.event.*;

import java.applet.*;

import java.net.*;

import java.util.*;

public class tunes extends Frame

implements ActionListener

{

Choice combo1;

Button button1,button2,button3;

AudioClip clip1;

Label label1;

String s;

public static void main(String args[])

{

tunes app=new tunes();

app.setSize(400,400);

app.show();

}

//---------------

tunes()

{

setLayout(new FlowLayout());

label1=new Label("choose the tune");

add(label1);

combo1 = new Choice();

combo1.addItem("spacemusic.au");

combo1.addItem("trips.mid");

combo1.addItem("cardring.wav");

combo1.addItem("chimes.wav");

combo1.addItem("flutemusic.aif");

add(combo1);

button1 = new Button("confirm");

button2 = new Button("stop");

button3 = new Button("exit");

add(button1);

add(button2);

add(button3);

s="tune";

label1 = new Label(s);

button1.addActionListener(this);

button2.addActionListener(this);

button3.addActionListener(this);

}

public void actionPerformed

(ActionEvent e)

{

if(e.getSource()==button1)

{

s = combo1.getSelectedItem();

try

{

URL url = new URL("file:/c:/"+ s);

clip1 = Applet.newAudioClip(url);

clip1.play();

}catch(Exception e1)

{System.out.println(""+e1);}

}

if(e.getSource()==button2)

{

clip1.stop();

}

if(e.getSource()==button3)

{

System.exit(0);

}

======================================

We now take up JMF (Java Media Framework).We have to download JMF from

http://java.sun.com/products/java-media/jmf

The reference implementation is jmf2.1

It is about 4 mb zip file.( We are using the version meant for Windows platform). We can directly instal this in our system. The installation will automatically create the correct

classpath also.

We have imported java.media.* in the jmf program and it will be available now.

We get the selected URL of the media file when the user double-clicks on the list item. A mediaplayer instance is created by Manager.createPlayer(url) command.

The player generates controller events

and so we add listener for these events.We then provide a controllerUpdate() method, which is called when a Controller generates an event.

The player can have the following states.

1 Realizing: In the realizing state, the Player is in the process of determining its resource requirements. A realizing Player often downloads assets over the network.

2 Realized: In this state the Player knows what resources it needs and has information about the type of media it is to present. It can also provide visual components and controls.

3 Prefetching: During this phase, the Player preloads its media data, and does whatever else is needed to play the media data.

4 Prefetched: The state where the Player has finished prefetching media data -- it's ready to start.

5 Started: This state is entered when you call the start() method. The Player is now ready to present the media data.

Thus, when the player has been created and its realize() method is called, it does realizing task. When realizing is complete, it generates the corresponding event, and then the prefetch() method of the player is called. After this, the player is started.In order to simplify the code, we are dealing with audio only and we are not showing the visible component of the player.( which we illustrate in the next example).

*************************************

// jmfmusic.java

import java.awt.*;

import java.awt.event.*;

import java.net.*;

import java.io.*;

import javax.media.*;

public class jmfmusic extends Frame

implements ControllerListener,

ActionListener

{

Player player1 = null;

Component component1 = null;

URL url1;

Label label1;

List list1;

Button button1;

public static void main(String args[])

{

jmfmusic app = new jmfmusic();

app.setBounds(200,150,400,200);

app.show();

}

jmfmusic()

{

setLayout(new BorderLayout());

list1 = new List();

list1.addItem("spacemusic.au");

list1.addItem("chimes.wav");

list1.addItem("trips.mid");

list1.addItem("jayentho.mp3");

add("West",list1);

list1.addActionListener(this);

label1 = new Label("playing audio");

label1.setBackground(Color.black);

label1.setForeground(Color.green);

add("Center",label1);

button1 = new Button("exit");

button1.setBackground(Color.black);

button1.setForeground(Color.red);

add("South",button1);

button1.addActionListener(this);

}

public void actionPerformed

(ActionEvent e)

{

if(e.getSource()==list1)

{

String s = list1.getSelectedItem();

try

{

url1=new URL("file:/c:/"+s);

player1=Manager.createPlayer(url1);

player1.addControllerListener(this);

player1.realize();

label1.setText(s);

}

catch(Exception e1)

{label1.setText(""+e1); }

}

if(e.getSource()==button1)

{

System.exit(0);

}

public synchronized void controllerUpdate(ControllerEvent e2)

{

if(e2 instanceof RealizeCompleteEvent)

{player1.prefetch();}

if(e2 instanceof PrefetchCompleteEvent)

{ player1.start();}

}

public void stop()

{

player1.stop();

player1.deallocate();

}

==========================================

In the final demo(listjmf.java),we deal with audio-video files .The code is almost the same as above but for the addition of visible component and ControPanelComponent.

player1.getVisualComponent() and player1.getControlPanelComponent() are the required methods.These methods can be called only after the player has been realized. The code should be clear now.

We have tested the program with mpg, avi, wav,mid and au files.

-------------------------------------------

// listjmf.java

import java.awt.*;

import java.awt.event.*;

import java.net.*;

import java.io.*;

import javax.media.*;

public class listjmf extends Frame implements ControllerListener,ActionListener

{

Player player1 = null;

Component component1 = null;

Component component2 = null;

URL url;

List list1;

Button button1;

Label label1;

public static void main(String args[])

{

listjmf app = new listjmf();

app.setBounds(200,150,400,200);

app.show();

}

listjmf()

{

setLayout(new BorderLayout());

list1 = new List();

list1.addItem("good.avi");

list1.addItem("trips.mid");

list1.addItem("spacemusic.au");

list1.addItem("cardring.wav");

list1.addItem("somersault.mpg");

add("West",list1);

button1 = new Button("exit");

button1.setBackground(Color.black);

button1.setForeground(Color.red);

add("North",button1);

label1 = new Label();

label1.setBackground(Color.black);

label1.setForeground(Color.green);

list1.addActionListener(this);

button1.addActionListener(this);

}

public void actionPerformed(ActionEvent e)

{

if(e.getSource()==list1)

{

String s = list1.getSelectedItem();

String s1="file:/c:/"+s;

label1.setText(s1);

try

{

url1=new URL(s1);

player1=Manager.createPlayer(url1);

player1.addControllerListener(this);

player1.realize();

System.out.println("player realized");

}

catch(Exception e1)

{System.out.println(""+e1); }

}

if(e.getSource()==button1)

{

System.exit(0);

}

//------------------

public synchronized void controllerUpdate(ControllerEvent e2)

{

if(e2 instanceof RealizeCompleteEvent)

{ job1();}

if(e2 instanceof PrefetchCompleteEvent)

{job2(); }

}

//------------------------

void job1()

{

component1 =

player1.getVisualComponent();

component2 = player1.getControlPanelComponent();

invalidate();

if(component1 != null)

{ add("Center",component1); }

else { add("Center",label1);}

if(component2 != null)

{ add("South",component2);}

validate();

player1.prefetch();

}

//-------------------------

void job2()

{

player1.start();

}

//---------------------------

public void stop()

{

player1.stop();

player1.deallocate();

}

//--------------------

}

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JMF is a powerful package with much more functionality than what has been indicated here. This is just an introductory lesson. More details can be obtained from jmf site ============================================