Sign inJoin the beta

Demo analysis

Outdoor nets · from behind

Demo clip · stock footage · Gokuldham Nar on Pexels · Pexels License

Filmed from behind, so this demo shows the key moments but no measurements. For numbers, film side-on.

Full report

Keyboard shortcuts
Space
Play or pause
← →
One frame back or forward
Shift + ← →
Previous or next key moment
1 2 3 4
Speed 0.1×, 0.25×, 0.5×, 1×

What we saw

The key moments, in order. This clip was already in slow motion, so real-time seconds aren’t shown. Hollow dots are approximate.

Not checked by a coach yet

Film side-on at 120 or 240 fps for scores and angles

From behind we can follow the action, but knee, trunk and stride numbers need a side-on view.

Unlock more

What this clip couldn’t measure, and how to get it next time.

  • Film side-on17 measurementsTripod level with the crease and square to the pitch, whole body in frame from run-up to follow-through.Ball speed · Run-up speed · Pre-delivery stride · Take-off contact time · Jump height · Back foot to front foot · Back-knee bend after landing · Delivery stride · Front foot to release · Front knee at landing · Front knee after landing · Trunk bend at release · Braking at landing · Release height · Arm speed (approx.) · Run-up rhythm · Back hip at back-foot contact
  • Add your height1 measurementYour height turns pixels into centimetres for stride, jump and head movement.Head stability
  • Lab mode: two phones4 measurementsA second phone behind the bowler lets StumpSage measure rotation in 3D.Side bend at release · Shoulder counter-rotation · Hip–shoulder separation · Hip turn at release
  • Film a clearer clip4 measurementsCloser, in good light, with the whole body in frame for the whole delivery.Action type · Front-foot direction · Back-foot direction · Hip drop at landing

Capture quality

What the camera gave the analysis to work with.

  • Frame rateFine for the key moments. Slo-mo at 120 or 240 fps makes angles and scores accurate.
  • Slow motionExported already slowed down, by an amount we couldn’t work out, so no times or speeds are shown. Use the original file from the phone that filmed it instead.
  • FramingPart of the body left the frame. Keep the whole action in view.
Full reportThe key moments on the clip’s own frames, and what to film for numbers.

About this analysis

Demo clip · stock footage

Gokuldham Nar on Pexels · Pexels License

Stock footage for the demo, not a StumpSage athlete.

The key moments are found automatically; the ones we’re less sure of are drawn hollow.

How to film a delivery

Two minutes of set-up gives the most accurate numbers.

From this clip

  • Frame rateFine for the key moments. Slo-mo at 120 or 240 fps makes angles and scores accurate.
  • Slow motionExported already slowed down, by an amount we couldn’t work out, so no times or speeds are shown. Use the original file from the phone that filmed it instead.
  • FramingPart of the body left the frame. Keep the whole action in view.
  • Side-on, square to the pitchStand level with the bowling crease, on the side of the bowling arm, so the run-up crosses the frame.
  • Tripod at hip heightA steady phone at about 1 m keeps angles true. Lean it on a kit bag if you have no tripod.
  • 12–15 m from the creaseFar enough to fit the last strides, the jump and the follow-through without zooming.
  • Slo-mo at 240 fpsSwitch the camera to Slo-mo. At 240 fps the arm and the landing foot stay sharp; 120 fps works too.
  • Run-up to follow-through in frameStart recording before the run-up and stop after the follow-through. Keep the whole body in view.
  • Good light, plain backgroundFilm with the sun behind you if you can, and avoid other players walking through the shot.

The full filming guide