Gully DRS: replay, ball tracking and edge detection on a phone

Every gully batsman swears he wasn't out. So I built DRS for our gully with Claude, and it runs on one phone.

What it does

You put a phone behind the stumps and record the ball. When someone appeals and the argument starts, you hit review.

Review plays the clip back in slow motion, frame by frame. Everyone gets to look at the same footage instead of at each other.

Two more pieces sit on top of the replay. One is ball tracking. The other listens for the nick.

How the ball tracking works

You do the spotting and the app does the line. Three taps are all it needs. You tap where the ball pitched, where it reached the batter, and the stumps.

From those points it carries the line on to the stumps and makes the call. In the reel, the batter leaves one alone. The line misses the stumps, and the call is not out.

Because the line comes from your taps, the result depends on where you place them. Take a moment over the pitch point, the batter and the stumps before you announce anything. Those three marks are the input, so they are where a bad call would come from.

The nick

The app also listens for the nick. That gives a review three things to look at, the slow-motion replay, the tracked line and the sound.

The reel only shows this briefly, so treat it as an extra check on the same delivery. Run it alongside the replay and the tracking and see what the three say together.

What to expect from it

The test clip in the reel is free stock footage from Pexels. That's the clip the demo runs on.

The tracking is an estimate from your taps, made for gully arguments. Use it to settle the debate at your own game, and keep your expectations at that level.

Try it

Set a phone behind the stumps at your next game and record a few deliveries. Run a review on the first close call, tap the pitch point, the batter and the stumps with care, and see what call comes back. Then send the reel to the friend who has never been out.