JaWavedit - The Java Wave-Editor : THE MODULE CONCEPT

The Method apply is called by JaWavedit whenever your class is chosen.
You get class Wavefile and the beginning and end sample of the selection as parameters. You will use WaveFile to access the array where the sound data is stored. The most important field of WaveFile is short[]Wave (only Simple Module). You can read and modify this array which represent a mono voice.
Your module is called automatically twice for stereo voices.
To limit your modifications to the current selection (marked red in the graph) use int SelStart and int SelEnd. These values hold the current selection.
A very simple example of how to implement a SimpleModule is the Clear module. It creates a new array which includes the old wave but the current selection:

public class Clear implements
SimpleModule {

    public void apply(WaveFile wf,int SelStart,
int SelEnd){

    short temp[];

    temp=new
short[SelStart+(wf.getSize()-1-SelEnd)];

    if (SelStart>0)

    System.arraycopy(wf.Wave,0,temp,0,SelStart);

    if (SelEnd<wf.getSize()-1)

   
System.arraycopy(wf.Wave,SelEnd+1,temp,SelStart,(wf.getSize()-1-SelEnd));


    wf.Wave=temp;

}

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4.StereoModule
We provide another way to access the sound. If you implement StereoModule instead of SinmpleModule, you can separately modify the two voices short[]WaveLeft and short[] WaveRight. In addition to that, you may set up a graphical user interface, as you may use in your constructor a parameter of type "Frame" to get the parent Frame. This is necessary to instantiate a Dialog class, which is proposed to use for an interface.

See the documentation of WaveFile for more info about it.
Here is an example of an implementation of a StereoModule:

// Include awt classes:

import java.awt.*;

import java.awt.event.*;

// inherit from Dialog and implement any optional Listeners you
need:

public class MyJWModule extends Dialog implements StereoModule, 

AdjustmentListener, ActionListener, WindowListener 

{

    // set up some fields with awt elements 

    private Label lab;

    private Scrollbar bar;

    private Checkbox choice;

    private Button go;

    private Button stop;

    private Button test;

    //fields to store wave data:

    private WaveFile wf;

    private short[] leftWave;

    private short[] rightWave;

    private int selStart;

    private int selEnd;

    // create your constructor which takes a frame
as parameter

    // this constructor is only called once

    public MyJWModule(Frame parent) {

    // call the constructor of dialog

    super (parent,true);

    setTitle ("MyJWModule by Ernie and
Bert");

    addWindowListener(this);

    setResizable(true);

    // see the Java dokumentation for more
information about 

    // positioning of awt elements 

    Panel p = new Panel();

    add (p);

    // initialise your elements

    lab = new Label("this scrollbar will
..."); 

    p.add (lab);

    bar = new Scrollbar();

    bar.addAdjustmentListener (this);

    p.add (bar);

    choice = new Checkbox ("select to
...");

    p.add (choice);

    go = new Button ("GO !");

    go.addActionListener (this);

    p.add (go);

    stop = new Button ("NO STOP");

    stop.addActionListener (this);

    p.add (stop);

    test = new Button ("What will happen
?");

    test.addActionListener (this);

    p.add (test);



    // pack 'em

    pack();

}

//function which is called when selecting
its menu:

public void apply(WaveFile waveFile,Selection sel) {

    //copy parameters to be treated when the right
button is pressed: 

    leftWave=waveFile.getLeftWave();

    rightWave=waveFile.getRightWave();

    wf=waveFile;

    selStart=sel.start;

    selEnd=sel.end;

    // display this dialog

    setVisible(true);

}



public void actionPerformed (ActionEvent e) {

    if (e.getSource()== go) { 

        // action:

        // treat the arrays
leftWave[] and rightWave[]

    }

    if (e.getSource()== stop) {

        // stop it

        // don't forget to set
modifications before leaving 

       
wf.setWaves(leftWave,rightWave);

        // you can leave at
this point

        setVisible(false);

    }

    if (e.getSource()== test) {

        // apply with buffer

    }

}

public void windowClosed(WindowEvent
event) {}

public void windowDeiconified(WindowEvent event) {}

public void windowIconified(WindowEvent event) {}

public void windowActivated(WindowEvent event) {}

public void windowDeactivated(WindowEvent event) {}

public void windowOpened(WindowEvent event) {}

public void windowClosing(WindowEvent event) {
setVisible(false);} 

}

See examples of JWModules in the directory demo for further information.

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5.Exit module
You leave the module by calling setVisible(false). As a modal Dialog, it now finishes and gives the flow of execution back to JaWavedit. In a JWModule without a graphical user interface, your module is finished when the method apply is left.

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6.Compiling
Your .java should be in a sub-directory of JWModules. You compile it by selecting it in the menu structure of Options|Modules|Compile. If it does not appear there, select first Reload Modules.

If compiling from within JaWavedit is not possible (e.g. you don't use the JDK), compile it with JaWavedit.jar in your classpath (see jw for Unix or JaWavedit_run.bat for more details)

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7.Test
Start JaWavedit or choose reload modules to include your module in the Modules menu. From there you simply start it by clicking ist menu entry.

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8.Debugging
I admit, debugging is not very easy. Very helpful is the Debug window. Select Windows|Debug to see it. When you compile modules, you'll see there the progress of compilation and eventually the errors.

While reloading the Modules, information relative to loading the modules is output.And finally, any errors that occur during execution of a module is also printed to Debug.

You have also the possibility to output your own error messages: Make a call to Globals.debugOut .
These parameters are supported:

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9.Useful JaWavedit methods
To see all available methods of the class WaveFile have a look at its documentation. In the directory MCK you'll find as well the documentation of Selection and Player, which you might want to use in order to play sound in your module. However, at present, this class is only documented in french. Refer to the source code of SimpleModule, StereoModule, WaveFileException to get to know them. We now provide also other sources and classes that you can use in your JWModules. Most of the comments are in French, but we hope to translate them and add also some examples of using them.

There are also the 2 classes LangBase.java and Lang.java. You can access their public functions in your Modules, as they are static. For example, this gets the string for "File" in the current language:

If you'd like to translate Lang and LangBase to your language, go ahead ! Send it to us per email and we'll include in the next version.

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11.Thank You
When your JWModule is ready to see the wide world (web), send it to us per email. We will include it to the web-page. Like this, we hope to construct a small database of JWModules and therefore making JaWavedit an unlimited Wave-Editor. We'll keep on working on enhancing the application.

•Delay : Various filters which apply delay effects - listen to hear the effect. They are included in the demo directory.	• Pong SimpleModule which applies an "ping- pong"-effect to the wavefile. It is just a long delay.	• Echo : SimpleModule which applies an echo-effect to the wavefile. • Robotz try it !
•Volume : Modifications on volume	•Volume : StereoModule to change volume with sliders - needs some enhancement to change the Volume according to logarithmic function. Source included.	•FadeOut : guess what . •FadeIn: fading the sound in the selection from 0 to original value
•Base : SimpleModules with simple modifications. Source in the demo directory.	•Reverse : reverses the sound - sounds like playing in the other direction •CreateTones : Create sine, square, triangle and saw waves. (not perfect though...)	•Trim : erases everything but the selection •Clear : erases the selection
•Info : StereoModules that are not directly related to sound modifications	•Codage : Module to encode any written message in the data without changing the sound. Password protection. For understandable reasons the source code is not available.	•Info : Read and modify the text string which is in the header of any .au file.