Analyze
Scan session
One click finds your forehands, backhands and serves, scores them, tells you who you look like and what to work on. What each result means.
On this page
Scan session is the heart of Racketlens. In one click the app finds your strokes across the whole video, measures how repeatable they are, compares them with the pros and suggests drills. You don’t select or mark anything.
Scanning step by step#
- Open your video. A new video opens straight on the Session tab.
- Leave the typical-stroke box ticked. The Save my typical stroke to my account box keeps a few seconds of your most representative stroke, so the history can show two sessions side by side.
- Press Scan session. Below the button you see how long it will take.
- Keep watching the video if you like. The scan works in the background: the player stays free. You see each stage, the time left and how many hits it has checked.
- Read your results. A card appears for each kind of stroke: backhands, forehands and serves.
How long it takes#
It depends on the length of the video and how many hits it has. As a guide, on a recent computer: a 5-minute session takes about a minute, a 16-minute one under three, and a 2-hour one about 12 minutes.
Stop and continue#
Press Stop at any time: what’s done is kept. When you come back, the button says Continue the scan and it picks up where it left off.
The stages#
- Finding the hits in the sound: the sound of the ball on the strings marks every hit in the video (yours or anyone else’s).
- Recognising your strokes: it tracks the body of whoever hits to tell whether the stroke is yours and whether it’s a forehand, a backhand (one- or two-handed) or a serve.
- Following your body through each stroke: it measures each stroke in detail (up to 40 per kind, spread over the whole session).
- Comparing with the pros, Picking the key frames, Saving your typical stroke to your account.
- Following the ball: only if you’ve already calibrated the court.
Who are you? (group lessons)#
When more than one person hits in the video, the scan pauses and asks Who are you in this video?. It shows a picture of each person, grouped by shirt colour, with how many strokes they have.
- Press This is me under your picture. Only your strokes are scored; the others’ are set aside.
- If they really are all you (you changed shirts, say), press They’re all me.
- Picked wrong? Choose again.
Your results#
For each kind of stroke with at least 3 of yours, the scan shows a card. When the session has more than 40, it analyses 40 spread over the whole session and says so (40 of … strokes analysed).
The score#
A number from 0 to 100 with a label: solid (75 or more), on the way (55 to 74) or needs work (under 55). It combines two things:
- Technique (60 %). How far your strokes sit outside what pro strokes have in common at three moments: the end of the backswing (on a serve, the racket drop), contact and the finish. 90 is as close as a typical pro clip. It doesn’t reward looking like one particular player, but being within what nearly all of them do.
- Consistency (40 %). How alike your strokes are to each other. 100 would be repeating exactly the same stroke.
The camera#
The app detects where you filmed from (side, behind or front) from where your head points during your strokes. If it got it wrong, tap the right one. It only changes which pro clips you’re compared with.
You look like…#
The three pros whose stroke is closest to your usual one, with a percentage: 100 = identical. For scale, two strokes by the same pro score about 70. It’s a style hint, not a verdict.
Your model#
Your model: … is the pro who makes the best example for you: their stroke clearly shows what you need to change, with a style close to yours. Press Compare with … to see your stroke and theirs side by side, already synced at three phases, or try the runner-up. More in Compare with pros.
By phase#
Above the fundamentals, the By phase block scores each of the stroke’s five phases (the median over the session’s strokes) against what pros do, and below it shows the five frames of your typical stroke with the measurements drawn on them. Click one to jump to that moment of the video.
The What to work on box names the weakest phase and its measurement furthest from the pro range, with drills and the Ask the AI coach about this phase button. If every phase is fine but the fundamentals have gaps, it points you to them; if the phases couldn’t be scored (the pro library didn’t load during the scan), it says so. Phases marked ~ don’t count: a phase that was ~ in every stroke shows ~ instead of a score. Each stroke also has its own step by step.
Fundamentals to work on#
Up to three sentences on where your stroke is clearly outside what the pros do, with your number and the pros’ range. For example: “Racket hand higher at the finish (you 0.26 torso; most pros 1.05–1.65)”.
A torso is a length: from your hips to your shoulders. Measuring in torsos makes the number independent of your height and of how far away the camera was. Every measure is explained in What the numbers mean.
Drills for this session#
Drills picked for what the scan found, with Add to my plan to put them in your plan. See Drills and practice plan.
Your typical stroke#
Five frames of your most representative stroke, one per phase (see By phase); older scans have three: End of backswing (on a serve, Racket drop), Contact and Finish. Click one to jump to that moment of the video. Watch the typical one and Watch the one closest to … take you to those strokes.
The ball#
If the court is calibrated, the scan follows the ball of a few strokes of each kind (up to 4) and shows the margin over the net, the depth, the speed and how many went in. The Ball tab analyses the rest. If you haven’t calibrated, the card invites you to (it takes about a minute). See Ball analysis.
Consistency in detail#
Open Consistency in detail for your averages on each measure and the strokes that broke your pattern.
When something doesn’t work#
| Message | What to do |
|---|---|
| The video has no sound | Mark them yourself: put the playhead on each stroke’s contact and press Mark a hit here (H) (or H). With 3 or more, **{{session.scanMarked |
| No ball hits were heard | Raise the Sensitivity in the Shots tab and scan again, or mark them yourself as in the row above. |
| Did you film in slow motion? | If everyone moves several times slower than in a real stroke, the video is almost surely slow motion playing slowed down. Pick **{{session.slowMoYes |
| Hits were heard, but none was clearly yours | You’re too small in the picture or out of it. Zoom in on yourself on the video and scan again, or film closer. |
| Not enough strokes of one kind | Each kind needs at least 3 of your strokes. Review my strokes (Shots tab) opens the list: Others may hold strokes of yours that weren’t recognised. |
| Your strokes changed since this scan (new, relabelled or removed). Scan again to update it. | You fixed strokes in Shots: press Scan again. |
More cases in Troubleshooting.