Shoot it.
Step through every frame.

Every frame, not the playback copy

A slow-motion clip picked the usual way comes back as a 30 fps render with most of its frames gone. Replay Breakdown opens the original file, so a 240 fps clip keeps all 240 frames a second. The newest clip in your library is one tap from the home screen, with your recent clips and the ones you've already drawn on beside it.

Play it, step it, name it

Play the clip at real, half or quarter speed. Tap the strip under the picture to jump, or drag the ruler beneath it, which moves exactly one frame per tick however long the clip. Name the frames that matter — the set-up, the pop, the catch, the landing — and they're flagged on the scrubber, one tap away.

Draw and measure

Lines and arrows that snap level and plumb, angles read off the picture as it really is rather than as the screen squashes it, circles, a freehand pen, and an airtime timer that counts up from take-off to landing and holds the total. Five colours, and each drawing shows for one frame, half a second, or the rest of the clip.

Measure it

Draw a line along something you know — the board, a rim, a lane line — and say how long it is. Every line after reads its real length, in centimetres or inches: pop height, stride, how far the landing was from the coping. Tap a point, step on a few frames, tap again, and it reads how fast it went, by the clip's own clock. Lengths read right in the same plane as the one you know, and less so toward the edges of a wide lens.

Side by side

Put two clips on the same moment — the pop, the take-off — and link them there, or in one tap if both have the pop named. From then on they move together, frame by frame, each at its own frame rate, side by side or one laid over the other. Last week's attempt against today's, or the student against the pro.

Talk it through

Press the microphone and talk while you scrub, draw and zoom, the way you'd explain it standing next to them. Play it back to check it, then send it as one video: your voice over every frame you stepped to and every line you drew, in step.

Send it back

Trim to the move, then export at real speed, half speed or quarter speed as an MP4 that plays in any messenger, with the drawings and the timer painted in. Or save the one frame that says it all as a full-size picture.

The whole move in one picture

Lay the trimmed move into a sequence still: the rider at every stage, from three to ten of them, over the same background. It works from a tripod or a phone held still, and says so when the camera moved.

On iPad, with Apple Pencil

The Pencil draws while your fingers scrub and zoom. Double-tap or squeeze for the tool you used before. Open two clips in two windows with Stage Manager.