Increasing screen capture speed when using Java and awt.Robot

Question

Edit: If anyone also has any other recommendations for increasing performance of screen capture please feel free to share as it might fully address my problem!

Hello

Answer 1

Re-using the screen rectangle and robot class instances will save you a little overhead. The real bottleneck is storing all your BufferedImage's into an array list.

I would first benchmark how fast your robot.createScreenCapture(screenRect); call is without any IO (no saving or storing the buffered image). This will give you an ideal throughput for the robot class.

long frameCount = 0;
while( (System.currentTimeMillis() - startTimeMillis) <= recordTimeMillis ) {
    image = m1.captureScreen();
    if(image !== null) {
        frameCount++;
    }
    try {
        Thread.yield();
    } catch (Exception ex) {
    }
}

If it turns out that captureScreen can reach the FPS you want there is no need to multi-thread robot instances.

Rather than having an array list of buffered images I'd have an array list of Futures from the AsynchronousFileChannel.write.

• Capture loop
• • Get BufferedImage
• • Convert BufferedImage to byte array containing JPEG data
• • Create an async channel to the output file
• • Start a write and add the immediate return value (the future) to your ArrayList
• Wait loop
• • Go through your ArrayList of Futures and make sure they all finished

Answer 2

I guess that the intensive memory usage is an issue here. You are capturing in your tests about 250 screenshots. Depending on the screen resolution, this is:

1280x800 : 250 * 1280*800  * 3/1024/1024 ==  732 MB data
1920x1080: 250 * 1920*1080 * 3/1024/1024 == 1483 MB data

Try caputuring without keeping all those images in memory.

As @Obicere said, it is a good idea to keep the Robot instance alive.