Errors in code that captures images from webcam

Question

Here is the code
import javax.swing.*;
import javax.swing.border.*;
import java.io.*;
import javax.media.*;
import javax.media.datasink.*;
import javax.media.format.*;
import javax.media.protocol.*;
import javax.media.util.*;
import javax.media.control.*;
import java.util.*;
import java.awt.*;
import java.awt.image.*;
import java.awt.event.*;
import com.sun.image.codec.jpeg.*;
// import com.sun.media.vfw.VFWCapture; // JMF 2.1.1c version
import com.sun.media.protocol.vfw.VFWCapture; // JMF 2.1.1e version
public class JWebCam extends JFrame
implements WindowListener, ComponentListener
protected final static int MIN_WIDTH = 320;
protected final static int MIN_HEIGHT = 240;
protected static int shotCounter = 1;
protected JLabel statusBar = null;
protected JPanel visualContainer = null;
protected Component visualComponent = null;
protected JToolBar toolbar = null;
protected MyToolBarAction formatButton = null;
protected MyToolBarAction captureButton = null;
protected Player player = null;
protected CaptureDeviceInfo webCamDeviceInfo = null;
protected MediaLocator ml = null;
protected Dimension imageSize = null;
protected FormatControl formatControl = null;
protected VideoFormat currentFormat = null;
protected Format[] videoFormats = null;
protected MyVideoFormat[] myFormatList = null;
protected boolean initialised = false;
* Constructor
public JWebCam ( String frameTitle )
super ( frameTitle );
try
UIManager.setLookAndFeel("javax.swing.plaf.metal.MetalLookAndFeel");
catch ( Exception cnfe )
System.out.println ("Note : Cannot load look and feel settings");
setSize ( 320, 260 ); // default size...
addWindowListener ( this );
addComponentListener ( this );
getContentPane().setLayout ( new BorderLayout() );
visualContainer = new JPanel();
visualContainer.setLayout ( new BorderLayout() );
getContentPane().add ( visualContainer, BorderLayout.CENTER );
statusBar = new JLabel ("");
statusBar.setBorder ( new EtchedBorder() );
getContentPane().add ( statusBar, BorderLayout.SOUTH );
* Initialise
* @returns true if web cam is detected
public boolean initialise ( )
throws Exception
return ( initialise ( autoDetect() ) );
* Initialise
* @params _deviceInfo, specific web cam device if not autodetected
* @returns true if web cam is detected
public boolean initialise ( CaptureDeviceInfo _deviceInfo )
throws Exception
statusBar.setText ( "Initialising...");
webCamDeviceInfo = _deviceInfo;
if ( webCamDeviceInfo != null )
statusBar.setText ( "Connecting to : " + webCamDeviceInfo.getName() );
try
setUpToolBar();
getContentPane().add ( toolbar, BorderLayout.NORTH );
ml = webCamDeviceInfo.getLocator();
if ( ml != null )
player = Manager.createRealizedPlayer ( ml );
if ( player != null )
player.start();
formatControl = (FormatControl)player.getControl ( "javax.media.control.FormatControl" );
videoFormats = webCamDeviceInfo.getFormats();
visualComponent = player.getVisualComponent();
if ( visualComponent != null )
visualContainer.add ( visualComponent, BorderLayout.CENTER );
myFormatList = new MyVideoFormat[videoFormats.length];
for ( int i=0; i<videoFormats.length; i++ )
myFormatList = new MyVideoFormat ( (VideoFormat)videoFormats );
Format currFormat = formatControl.getFormat();
if ( currFormat instanceof VideoFormat )
currentFormat = (VideoFormat)currFormat;
imageSize = currentFormat.getSize();
visualContainer.setPreferredSize ( imageSize );
setSize ( imageSize.width, imageSize.height + statusBar.getHeight() + toolbar.getHeight() );
else
System.err.println ("Error : Cannot get current video format");
invalidate();
pack();
return ( true );
else
System.err.println ("Error : Could not get visual component");
return ( false );
else
System.err.println ("Error : Cannot create player");
statusBar.setText ( "Cannot create player" );
return ( false );
else
System.err.println ("Error : No MediaLocator for " + webCamDeviceInfo.getName() );
statusBar.setText ( "No Media Locator for : " + webCamDeviceInfo.getName() );
return ( false );
catch ( IOException ioEx )
statusBar.setText ( "Connecting to : " + webCamDeviceInfo.getName() );
return ( false );
catch ( NoPlayerException npex )
statusBar.setText ("Cannot create player");
return ( false );
catch ( CannotRealizeException nre )
statusBar.setText ( "Cannot realize player");
return ( false );
else
return ( false );
* Dynamically create menu items
* @returns the device info object if found, null otherwise
public void setFormat ( VideoFormat selectedFormat )
if ( formatControl != null )
player.stop();
imageSize = selectedFormat.getSize();
formatControl.setFormat ( selectedFormat );
player.start();
statusBar.setText ( "Format : " + selectedFormat );
currentFormat = selectedFormat;
visualContainer.setPreferredSize ( currentFormat.getSize() );
setSize ( imageSize.width, imageSize.height + statusBar.getHeight() + toolbar.getHeight() );
else
System.out.println ("Visual component not an instance of FormatControl");
statusBar.setText ( "Visual component cannot change format" );
public VideoFormat getFormat ( )
return ( currentFormat );
protected void setUpToolBar ( )
toolbar = new JToolBar();
// Note : If you supply the 16 x 16 bitmaps then you can replace
// the commented line in the MyToolBarAction constructor
formatButton = new MyToolBarAction ( "Resolution", "BtnFormat.jpg" );
captureButton = new MyToolBarAction ( "Capture", "BtnCapture.jpg" );
toolbar.add ( formatButton );
toolbar.add ( captureButton );
getContentPane().add ( toolbar, BorderLayout.NORTH );
protected void toolbarHandler ( MyToolBarAction actionBtn )
if ( actionBtn == formatButton )
Object selected = JOptionPane.showInputDialog (this,
"Select Video format",
"Capture format selection",
JOptionPane.INFORMATION_MESSAGE,
null, // Icon icon,
myFormatList, // videoFormats,
currentFormat );
if ( selected != null )
setFormat ( ((MyVideoFormat)selected).format );
else if ( actionBtn == captureButton )
Image photo = grabFrameImage ( );
if ( photo != null )
MySnapshot snapshot = new MySnapshot ( photo, new Dimension ( imageSize ) );
else
System.err.println ("Error : Could not grab frame");
* autoDetects the first web camera in the system
* searches for video for windows ( vfw ) capture devices
* @returns the device info object if found, null otherwise
public CaptureDeviceInfo autoDetect ( )
Vector list = CaptureDeviceManager.getDeviceList ( null );
CaptureDeviceInfo devInfo = null;
if ( list != null )
String name;
for ( int i=0; i<list.size(); i++ )
devInfo = (CaptureDeviceInfo)list.elementAt ( i );
name = devInfo.getName();
if ( name.startsWith ("vfw:") )
break;
if ( devInfo != null && devInfo.getName().startsWith("vfw:") )
return ( devInfo );
else
for ( int i = 0; i < 10; i++ )
try
name = VFWCapture.capGetDriverDescriptionName ( i );
if (name != null && name.length() > 1)
devInfo = com.sun.media.protocol.vfw.VFWSourceStream.autoDetect ( i );
if ( devInfo != null )
return ( devInfo );
catch ( Exception ioEx )
// ignore errors detecting device
statusBar.setText ( "AutoDetect failed : " + ioEx.getMessage() );
return ( null );
else
return ( null );
* deviceInfo
* @note outputs text information
public void deviceInfo ( )
if ( webCamDeviceInfo != null )
Format[] formats = webCamDeviceInfo.getFormats();
if ( ( formats != null ) && ( formats.length > 0 ) )
for ( int i=0; i<formats.length; i++ )
Format[] aFormat = formats;
if ( aFormat[i] instanceof VideoFormat )
Dimension dim = ((VideoFormat)aFormat).getSize();
// System.out.println ("Video Format " + i + " : " + formats.getEncoding() + ", " + dim.width + " x " + dim.height );
else
System.out.println ("Error : No web cam detected");
* grabs a frame's buffer from the web cam / device
* @returns A frames buffer
public Buffer grabFrameBuffer ( )
if ( player != null )
FrameGrabbingControl fgc = (FrameGrabbingControl)player.getControl ( "javax.media.control.FrameGrabbingControl" );
if ( fgc != null )
return ( fgc.grabFrame() );
else
System.err.println ("Error : FrameGrabbingControl is null");
return ( null );
else
System.err.println ("Error : Player is null");
return ( null );
* grabs a frame's buffer, as an image, from the web cam / device
* @returns A frames buffer as an image
public Image grabFrameImage ( )
Buffer buffer = grabFrameBuffer();
if ( buffer != null )
// Convert it to an image
BufferToImage btoi = new BufferToImage ( (VideoFormat)buffer.getFormat() );
if ( btoi != null )
Image image = btoi.createImage ( buffer );
if ( image != null )
return ( image );
else
System.err.println ("Error : BufferToImage cannot convert buffer");
return ( null );
else
System.err.println ("Error : cannot create BufferToImage instance");
return ( null );
else
System.out.println ("Error : Buffer grabbed is null");
return ( null );
* Closes and cleans up the player
public void playerClose ( )
if ( player != null )
player.close();
player.deallocate();
player = null;
public void windowClosing ( WindowEvent e )
playerClose();
System.exit ( 1 );
public void componentResized ( ComponentEvent e )
Dimension dim = getSize();
boolean mustResize = false;
if ( dim.width < MIN_WIDTH )
dim.width = MIN_WIDTH;
mustResize = true;
if ( dim.height < MIN_HEIGHT )
dim.height = MIN_HEIGHT;
mustResize = true;
if ( mustResize )
setSize ( dim );
public void windowActivated ( WindowEvent e ) { }
public void windowClosed ( WindowEvent e ) { }
public void windowDeactivated ( WindowEvent e ) { }
public void windowDeiconified ( WindowEvent e ) { }
public void windowIconified ( WindowEvent e ) { }
public void windowOpened ( WindowEvent e ) { }
public void componentHidden(ComponentEvent e) { }
public void componentMoved(ComponentEvent e) { }
public void componentShown(ComponentEvent e) { }
protected void finalize ( ) throws Throwable
playerClose();
super.finalize();
class MyToolBarAction extends AbstractAction
public MyToolBarAction ( String name, String imagefile )
// Note : Use version this if you supply your own toolbar icons
// super ( name, new ImageIcon ( imagefile ) );
super ( name );
public void actionPerformed ( ActionEvent event )
toolbarHandler ( this );
class MyVideoFormat
public VideoFormat format;
public MyVideoFormat ( VideoFormat _format )
format = _format;
public String toString ( )
Dimension dim = format.getSize();
return ( format.getEncoding() + " [ " + dim.width + " x " + dim.height + " ]" );
class MySnapshot extends JFrame
protected Image photo = null;
protected int shotNumber;
public MySnapshot ( Image grabbedFrame, Dimension imageSize )
super ( );
shotNumber = shotCounter++;
setTitle ( "Photo" + shotNumber );
photo = grabbedFrame;
setDefaultCloseOperation ( WindowConstants.DISPOSE_ON_CLOSE );
int imageHeight = photo.getWidth ( this );
int imageWidth = photo.getHeight ( this );
setSize ( imageSize.width, imageSize.height );
final FileDialog saveDialog = new FileDialog ( this, "Save JPEG", FileDialog.SAVE );
final JFrame thisCopy = this;
saveDialog.setFile ( "Photo" + shotNumber );
addWindowListener ( new WindowAdapter()
public void windowClosing ( WindowEvent e )
saveDialog.show();
String filename = saveDialog.getFile();
if ( filename != null )
if ( saveJPEG ( filename ) )
JOptionPane.showMessageDialog ( thisCopy, "Saved " + filename );
setVisible ( false );
dispose();
else
JOptionPane.showMessageDialog ( thisCopy, "Error saving " + filename );
else
setVisible ( false );
dispose();
setVisible ( true );
public void paint ( Graphics g )
g.drawImage ( photo, 0, 0, getWidth(), getHeight(), this );
* Saves an image as a JPEG
* @params the image to save
* @params the filename to save the image as
public boolean saveJPEG ( String filename )
boolean saved = false;
BufferedImage bi = new BufferedImage ( photo.getWidth(null),
photo.getHeight(null),
BufferedImage.TYPE_INT_RGB );
Graphics2D g2 = bi.createGraphics();
g2.drawImage ( photo, null, null );
FileOutputStream out = null;
try
out = new FileOutputStream ( filename );
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder ( out );
JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam ( bi );
param.setQuality ( 1.0f, false ); // 100% high quality setting, no compression
encoder.setJPEGEncodeParam ( param );
encoder.encode ( bi );
out.close();
saved = true;
catch ( Exception ex )
System.out.println ("Error saving JPEG : " + ex.getMessage() );
return ( saved );
} // of MySnapshot
public static void main (String[] args )
try
JWebCam myWebCam = new JWebCam ( "TimeSlice Web Cam Capture" );
myWebCam.setVisible ( true );
if ( !myWebCam.initialise() )
System.out.println ("Web Cam not detected / initialised");
catch ( Exception ex )
ex.printStackTrace();
when I run it I get the following errors
BufferToImage cannot convert buffer
could not grab frame
pls help

Answer 1

Do you expect anyone to read this?
http://forum.java.sun.com/help.jspa?sec=formatting
By the way, you have a condition that makes it print those messages. Check why that condiiton isn't rue.