DiscTrail+
An iPhone app that draws an animated flight trail onto a video of a throw and exports the clip back to the camera roll.
What to know
A clip is loaded from the photo library, the disc is marked frame by frame, and the app renders a smooth trail following it through the shot. The trace is adjustable: colour, thickness, opacity, and whether it tapers from wide to narrow along the flight. Everything runs on the phone, with no account, no login and no connection required, and the finished clip is exported straight back to the camera roll.
More detail
It measures nothing, which is the distinction worth knowing. Where Ace Trace overlays speed and distance on a traced flight, this is a drawing tool for showing a throw to someone else, whether for coaching, review or a highlight reel. A browser version runs the same editor, free for the first ten exports and then $2.99 a month after a one-month trial.
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