Question

I want to take a snapshot from a webcam through java. I followed this question and arrived at the this example. But there is a null pointer exception coming from the below line –

Buffer buf = frameGrabber.grabFrame();
Image img = (new BufferToImage((VideoFormat) buf.getFormat())
                .createImage(buf));
        buffImg = new BufferedImage(img.getWidth(this), img.getHeight(this),
                BufferedImage.TYPE_INT_RGB);

Through the debugger I observed that the buffer doesn’t actually contain data. So I went the creation of frameGrabber.

frameGrabber = (FrameGrabbingControl) player
                .getControl("javax.media.control.FrameGrabbingControl");

Is there a problem with this code. Because JMFStudio works fine in my machine but the code cannot access it. Thank you.

Answer 1

I found the solution. The JMF needs time for initialization. In the example we have to switch a line. Put the

new Timer(3000, this).start();

below the try catch.

The whole block looks like below.

        try {
            player = Manager.createRealizedPlayer(cdi.getLocator());
            player.start();
        } catch (NoPlayerException e) {
            e.printStackTrace();
        } catch (CannotRealizeException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
            new Timer(3000, this).start();
        // Grab a frame from the capture device
        frameGrabber = (FrameGrabbingControl) player
                .getControl("javax.media.control.FrameGrabbingControl");