delaymirror a rolling buffer, never a recording

Do the move.
Then watch it.

A mirror that runs a few seconds behind. Nail the turn, look up, see the turn. No pressing record, no scrubbing, no footage kept anywhere.

FROZEN

Nothing records — frames live in a rolling buffer in this tab and die there.

2.0s
keys: 0–9 set delay · space freezes — works with a bluetooth clicker

Programme note: a choreographer friend spends half of every rehearsal walking to her phone. Do the phrase, walk over, stop recording, scrub back, squint, walk back to centre, forget half of what she saw. The studios she trained at in Seoul had delay mirrors — a camera, a screen, and a few seconds of lag — and dancers there fix in one evening what takes a week of record-and-scrub. The hardware for that setup is a browser tab now. So: a mirror with a memory exactly seventeen seconds long, which turns out to be the perfect length — long enough to hold any phrase, too short to ever become surveillance.

— she stopped walking to her phone. the phone is the mirror now

The loop that teaches

why a delay beats a recording, mechanically

  1. Pick a delay a beat longer than the move. An eight-count at practice tempo is about six seconds; a lift takes three. Number keys set it instantly.
  2. Do the move, then just look. No walking, no buttons. You watch yourself while your muscles still remember what the attempt felt like — that pairing is where the correction happens.
  3. Adjust and go again. The buffer rolls forever; the loop repeats as fast as you can. Freeze (space bar) when a single frame deserves a longer look, save it if it's worth keeping.
  4. Check the true view before you perform. Untick mirroring to see what the audience sees — it's flipped from your instinct, and better to meet that stranger in rehearsal.

Who stands in front of it

the regulars, from the field

House rules, posted honestly

what this mirror will and won't do

Shouted from the back row

quick answers between runs

Can I cast it to the studio TV?

Anything that mirrors a browser works — HDMI cable, AirPlay, Chromecast tab casting. The laptop camera faces the floor; the TV shows the delayed image. Cast latency adds a fraction of a second to your set delay, which for practice purposes changes nothing.

Does a longer delay use more of my phone?

Linearly, and it's modest — fifteen seconds of buffer holds a few hundred compressed frames, around ten megabytes. Old phones cope; the deliberate 15-second cap is what keeps that promise.

Why does the image pause for a moment when I lengthen the delay?

You asked to see further into the past than the buffer currently holds, so it shows a filling countdown until that moment exists. Shortening the delay is instant — that past is already in the tin.

Front camera or back?

Front lets you glance at the phone itself; back gives a better lens if you're casting to a bigger screen. The switch button appears on phones; the mirror toggle follows automatically but stays overridable.

Two people practising — can we both use it?

Same mirror, wider frame: step back until you're both in shot. Duets, spotting partners, and coach-plus-athlete all work; the mirror doesn't care how many people the past contains.

Zines from the studio

longer reads, taped to the mirror

The feedback loop that teaches faster What motor-learning research says about seeing your attempt seconds — not minutes — after you make it. The mirror is lying to you Why you look wrong in photos, right in mirrors, and what true view means for performers. Build a practice corner for under nothing Phone placement, TV casting, clicker controls — a studio-grade delay setup from stuff already in the house.

Encore log

what changed, newest first

v1.0
opening night: 0–15 second delay with slider and number-key control, mirrored and true view, freeze on space bar, frame save, fullscreen studio mode, camera switching, wake lock, filling countdown, rolling buffer that never touches disk, offline PWA.