Can I make a video of a running Java Swing application on the fly?

Question

Hello everyone,

I have a Java swing GUI program that renders anywhere between 1 and 25 frames per second. It is only one window and only one panel to which I do all the rendering, e.g. no other Swing components.

I need to be able to produce videos of test runs of my program as it runs. The problem is that regular screen casting tools (e.g. 3rd party apps I start before running my code) often miss some of my frames and I need an accurate video.

I know how to use the Robot class to capture screenshots of my Java window, but I can't possibly be saving them to disk as I run, it will slow everything down too much. Is there a way for me to use the Robot class (or maybe some other piece of code) to create a video of my window on the fly, while running my program?

Thanks!

Answer 1

If you run your program in Linux, you can take advantage of recordmydesktop. It is one of the better recording programs I have used with controls over the framerate and whatnot.

Answer 2

Can't you adapt your program to dump the contents of your window after each update along with an accurate timestamp? Then post process these into a movie if you need that.

That will give you full control.

Answer 3

If you just want to save the visual changes, you can use some screen capping software:

Open source screenshot capper: http://www.donationcoder.com/Software/Mouser/screenshotcaptor/index.html (or just use plain alt+print screen, ctrl v for each state) Open source video capper: http://camstudio.org/

Answer 4

You can use ffmpeg wrapper in Java - Xuggler and builtin Java Robot class. Here is sample code with Xuggler.

final Robot robot = new Robot();
final Toolkit toolkit = Toolkit.getDefaultToolkit();
final Rectangle screenBounds = new Rectangle(toolkit.getScreenSize());

// First, let's make a IMediaWriter to write the file.
final IMediaWriter writer = ToolFactory.makeWriter("output.mp4");

// We tell it we're going to add one video stream, with id 0,
// at position 0, and that it will have a fixed frame rate of
// FRAME_RATE.
writer.addVideoStream(0, 0,
 FRAME_RATE,
 screenBounds.width, screenBounds.height);

// Now, we're going to loop
long startTime = System.nanoTime();
for (int index = 0; index < SECONDS_TO_RUN_FOR*FRAME_RATE.getDouble(); index++)
{
    // take the screen shot
   BufferedImage screen = robot.createScreenCapture(screenBounds);

   // convert to the right image type
   BufferedImage bgrScreen = convertToType(screen,
   BufferedImage.TYPE_3BYTE_BGR);

   // encode the image to stream #0
   writer.encodeVideo(0,bgrScreen,
   System.nanoTime()-startTime, TimeUnit.NANOSECONDS);
   System.out.println("encoded image: " +index);

   // sleep for framerate milliseconds
  Thread.sleep((long) (1000 / FRAME_RATE.getDouble()));
}
// Finally we tell the writer to close and write the trailer if
// needed
writer.close();

Another option is Screentoaster site - but I'm note sure what frame rate it provide.