Drag on the screen to paint light into the loop. New here? Open the Guide.
Drop to feed it into the loop
Keys: 1–0 channels · Space freeze · N neutral · R surprise · P autopilot · C clear · F full screen · H hide controls · G guide
Phosphor Loop
QUICK GUIDE · ABOUT 3 MINUTES
How to play Phosphor Loop
Video feedback is what happens when a camera films the screen it’s plugged into. Every frame goes back in a little zoomed, turned and tinted, so anything on screen leaves a trail of echoes. Phosphor Loop runs that loop sixty times a second, and you steer it.
INPUTA pattern, picture, video, camera, screen or phone
→
LOOPZoom, spin, warp, fade and tint the last frame
→
SCREENWhat you see, with an optional old-TV glass
↻ the screen is fed back into the loop sixty times a second
Start hereYour first 30 seconds
Pick a channel. The ten buttons at the top of the controls are ready-made looks. Keys 1 to 9 and 0 work too.
Drag on the screen. You paint light straight into the loop and watch it echo.
Move Zoom and Spin. They change the picture the most. Double-click a slider to put it back.
Press Surprise me for something new, or Autopilot to let it run by itself.
ReferenceWhat the controls do
Channels
Channels 1 to 0
Ready-made looks. 9 (Twins) and 0 (Weave) use both loops.
Neutral
Just loop A’s input filling the screen, with every effect off. A clean starting point: raise Trails, then Zoom and Spin.
Surprise me
Random settings. Press it a few times.
My presets
Save current look keeps every setting under a name, with a snapshot of the picture. Presets stay in this browser on this device. Save with the same name to update one.
Autopilot
Changes the settings slowly by itself, fading between the two loops every half minute or so. Touch any control and you’re back in charge.
Mix the two loops
What you see
Show loop A, loop B, or both laid over each other.
Feed A into B, Feed B into A
Pour one loop’s picture into the other loop’s trails. Use one for a one-way flow, or both and the loops trade shapes.
Loop A and Loop B tabs
Pick which loop the controls below change. A red light means that loop is on screen.
What feeds the loop
Wave, Shape, Bars, Sparks
Built-in patterns that need no setup.
Picture and Video
Your own files. Video gets a tape deck: scrub, skip 5 seconds, change speed, and repeat a section.
Camera, Screen, Phone
Live pictures. Screen shares this tab so the screen films itself. Phone shows a QR code to scan.
Loop A’s or Loop B’s picture
Feed the other loop straight in as an input. At Input size 50 it lines up with the screen.
Second input and Blend
Mix two inputs into the same loop.
Input size
How big the input sits on screen, up to filling it.
Only movement
For live inputs and video: only what moves gets in.
Adjust the picture
Under each picture, video or live input: Tracking (worn-tape wobble), Brightness, Contrast, Color, Cut out dark parts, and Hold this frame.
Shape the loop
Zoom
In makes a tunnel. Out shrinks the picture into itself.
Spin
Twists every echo. Small amounts make spirals.
Trails
How long echoes last. High is dreamy, low is snappy, and None turns the feedback off.
Color shift
Moves each echo a little further round the rainbow.
Warp
Wobbles the echoes like water.
Mirror
A kaleidoscope with 2 to 8 sides.
React to sound
Computer sound
Listens to whatever this computer is playing: Spotify, YouTube, games. Chrome asks what to share: on the Entire Screen tab pick any screen (with two monitors, Screen 1 or Screen 2 both give the whole computer’s sound) and switch on Also share system audio. For Spotify in a browser tab, pick that tab and switch on Also share tab audio.
Microphone
Listens to the room, so music from a speaker or a clap works. Listen to picks which input when there’s more than one.
Stereo Mix (Windows)
Hears the computer’s sound with no screen sharing at all: choose Microphone, then Stereo Mix under Listen to. If it isn’t listed, turn it on once in Windows Settings → System → Sound → More sound settings (Sound Control Panel on Windows 10) → Recording tab → right-click an empty spot → Show Disabled Devices → right-click Stereo Mix → Enable, then reload this page. Some computers don’t have it.
The meter
Low, Mid and High bars and a BEAT light show what it hears. It adjusts itself to the volume.
Amount and What the music moves
How hard the picture reacts, and which settings follow the music: Zoom kick pumps on the bass, Input size swells, Spin follows the mids, Color follows the highs, Warp shakes and Flash brightens on beats.
Which browser
Computer sound works in Chrome and Edge. Firefox and Safari don’t pass sound through screen sharing, so use Microphone there (Stereo Mix on Windows hears the computer itself).
Record
Keeps the sound in the video while React to sound is on.
Screen and buttons
Old TV look
Scanlines, glow and curved glass. Turn it off for a clean picture.
Screen shape
Fill the space, or frame it as a 4:3 TV or 16:9.
Freeze and Clear
Hold the picture, or wipe it to black.
Auto-drift
Slowly moves the settings for you. Good for leaving it running.
Full screen and Hide controls
Show only the picture.
Output window
Opens the picture in its own window for a projector or second screen. Drag it over and double-click it to fill that screen. The controls stay here, and you can paint on the projected picture too.
Save picture and Record
Save a still, or up to a minute of video.
Hands onThings you can do with the screen
Paint by dragging on the screen with a mouse or finger. Paint goes into whichever loops are showing, and Mirror copies every stroke.
Drop a file, a picture or a video, onto the screen to feed it in.
Double-click any slider to put it back where the channel had it.
Fold away sections you’re not using by clicking their headings, or use Collapse all at the top of the controls.
1 … 0Channels
SpaceFreeze
NNeutral
RSurprise me
PAutopilot
CClear
FFull screen
HHide controls
GThis guide
EscClose the guide
RecipesSettings worth trying
Each recipe sets everything up. Press Try it, then nudge the sliders from there.
TroubleshootingIf something looks wrong
You’ve lost track of what you changed
Press Neutral to get back to just the input, then build up again.
The screen went white
Lower Trails or Color shift a little, or press Clear.
The screen is black
Raise Trails, make Input size bigger, or drag on the screen. Check the input isn’t set to Nothing.
Nothing is moving
Check that Freeze is off, then move Zoom or Spin, or turn on Auto-drift.
Camera, Screen or Phone won’t start
Allow access when the browser asks. The phone link only works from the https:// web address, with both devices online.
The output window didn’t open
The browser blocked it. Click the blocked pop-up icon at the right of the address bar, choose to always allow pop-ups for this page, then press Output window again.
The picture doesn’t react to music
Check that the Low, Mid and High bars move. With Computer sound, share again and make sure Also share system audio is switched on under the screen you pick (or Also share tab audio for a browser tab). If that switch never appears, use Microphone with Stereo Mix instead. Then raise Amount.
It’s choppy
Turn the Old TV look down, close other tabs, or choose 4:3 TV as the screen shape.