What's the best slow-motion speed for review?

0.5× is fine for footwork, tempo, balance. 0.25× is better for fast technical details, bat-speed, hand placement on submissions, golf impact, throw entry angles. Below 0.25× usually becomes too choppy unless the source was high-frame-rate.

How big are the exported files?

A trimmed 6-second 1080p slo-mo clip is typically 10–25 MB, well under WhatsApp's 100 MB limit. For full 45 s clips at 1080p, expect 70–150 MB, use Quick Share or AirDrop for those.

ReplayR

Instant replay camera for coaches

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Coach workflow · Updated 23 May 2026

How to share slo-mo clips with athletes

By Erwan Alliaume

TL;DR. Capture → trim → slow down → share peer-to-peer. Under 2 minutes from clip to athlete's phone, zero cloud upload. Works for gymnastics, BJJ, tennis, padel, dance, music, anything with a sub-90-second skill. The whole point: the athlete sees the clip while the kinaesthetic memory is still warm, and the footage never leaves the two phones.

The 5-step workflow

01. Mount & start the rolling buffer

Mount the phone for your sport, tripod behind baseline, mat-edge clamp, vault-runway tripod. Open ReplayR, set buffer to 45 s (single skills) or 90 s (routines / sparring rounds). Hit start. The phone now continuously records to a 45 s rolling memory.
02. Save the moment

When the rep happens, the throw, the rally, the dismount, the submission, tap save on your Wear OS watch (Tile or Complication) or on the on-screen button. The last 45 s is written from buffer to disk. Recording resumes in ~1 s.
03. Trim to the 4 seconds that matter

Open the saved clip in ReplayR's library. Drag the in/out handles to isolate the entry → execution → landing window. Save the trim, the full 45 s clip is still kept too in case you want a longer review later.
04. Slow it down

Apply 0.5× or 0.25× slow-motion. 0.5× for footwork, balance, tempo. 0.25× for fast technical details, bat speed, golf impact, submission grip switches, judo entry angle. Export as MP4 (1080p) to your gallery.
05. Share, peer-to-peer, no cloud

Android → Android: Quick Share / Nearby Share. Tap target phone, athlete accepts, done. No internet required.
iPhone in mix: AirDrop direct, or share via WhatsApp / Signal direct message.
Remote athlete: WhatsApp / Signal / Telegram (E2E-encrypted), 1-to-1 message, no public link.
Avoid: uploading to YouTube unlisted (still on Google's servers), TikTok drafts (analyzed for content), or public Drive links (link-shareable forever).

Why peer-to-peer matters

Minors

Under-18 footage in any cloud bucket is a parental-consent and GDPR conversation you don't want to have. Direct device-to-device sidesteps it.

Competitive secrecy

Pre-fight game plans, new BJJ guard concepts, unlisted gymnastics elements, you do not want a cloud breach to publish your edge.

Speed

Quick Share between two on-network phones is faster than waiting for an upload bar. Mat-side review happens in the moment.

Tips per sport

Tennis / padel: 0.5× on the contact frame, 0.25× on serve toss release.
Gymnastics: 0.25× for vault block, beam dismount rotation, bar release timing.
BJJ: 0.5× on the position switch, 0.25× on the grip break at the finish.
Boxing / Muay Thai: 0.25× on the combination, freeze-frame on the back foot at impact.
Dance / music: 0.5× full body / hands, side-by-side with reference (record both).