Android Asynctask to process live video frames

Question

I am using OpenCV to attempt to do some live video processing. Since the processing is fairly heavy, it delays the output frames significantly, making the live stream look

Answer 1

I would do something like that :

// Example value for a timeout.
private static final long TIMEOUT = 1000L;

private BlockingQueue frames = new LinkedBlockingQueue();

Thread worker = new Thread() {
    @Override
    public void run() {
        while (running) {
            Mat inputFrame = frames.poll(TIMEOUT, TimeUnit.MILLISECONDS);
            if (inputFrame == null) {
                // timeout. Also, with a try {} catch block poll can be interrupted via Thread.interrupt() so not to wait for the timeout.
                continue;
            }
            cropToCenter(inputFrame);
            String result = doImgProcessing(inputFrame);
        }
    }
};
worker.start();

public Mat onCameraFrame(Mat inputFrame) {
    inputFrame.copyTo(mRgba);//this will be used for the live stream
    frames.put(inputFrame);
    return mRgba;
}

The onCameraFrame puts the frame on the Queue, the worker Thread polls from the Queue.

This decorelate the reception and the treatment of the frame. You can monitor the growth of the Queue using frames.size().

This is a typical producer-consumer example.