Live visuals for a DJ set, from your browser
Phosphene turns a DJ set into live, audio-reactive visuals on a projector, TV or LED wall. It's free and runs in a browser tab, so all you need is a laptop and a way for it to hear the music. This guide covers getting the sound in, locking to the tempo, putting the picture on the big screen and keeping it interesting all night.
Open PhospheneFree, no sign-up. It runs in your browser.
- You need
- A laptop with Chrome or Edge, a projector or screen connected as a second display, and a way to hear the music: a mic, a line feed or software routing.
- Setup time
- About 15 minutes the first time.
- Price
- Free. Nothing to install, and it works offline after the first load.
Pick a setup
The only real decision is how Phosphene hears the music. Everything else is the same whichever you choose.
| Setup | How it hears the music | Best for |
|---|---|---|
| Mic in the room | The laptop's own microphone picks up the speakers | House parties, quick setups, anywhere you can't reach the mixer |
| Line feed from the mixer | A cable from the mixer's booth or record output into an audio interface | Clubs and gigs. The cleanest signal, with no crowd noise |
| Same laptop as the DJ software | A virtual audio cable passes the software's output to Phosphene | Practice, home sets and streams, when the music plays through the computer |
If someone else is DJing, a separate laptop for the visuals is the easy route: ask for a spare output on the mixer and you're independent of their gear. If you're DJing and doing visuals yourself, see running both on one laptop.
Get the music into Phosphene
Option 1: the microphone
- Open Phosphene and go to the Audio tab.
- Press Listen to Music Playing and allow microphone access when the browser asks.
- Watch the level bar move with the music, then set Sensitivity so the picture reacts without pinning at full.
Phosphene switches off the browser's echo cancellation and noise suppression for this, since both are made for voices and would flatten music. A mic still hears everything in the room, though, so in a loud club the crowd and the bass in the walls get mixed in. Keep the laptop near a speaker or the booth monitor rather than out in the crowd.
Option 2: a line feed from the mixer
This is what to use at a gig. You need a USB audio interface with a line input (any small two-input interface works) and a cable that fits the mixer's output, usually RCA to 1/4-inch jack.
- Find a spare output on the mixer. The record output (often labeled REC) is ideal, because on most mixers its level doesn't change when the DJ turns the master up or down. A booth output or a second master output works too, but it follows its own knob.
- Connect it to the interface's line input, and the interface to your laptop.
- Choose the interface as the input. Either make it your computer's default input (on a Mac, System Settings → Sound → Input; on Windows, Settings → System → Sound → Input), or pick it just for Chrome at
chrome://settings/content/microphoneusing the menu at the top. - In Phosphene, press Listen to Music Playing in the Audio tab, or Microphone, and set Sensitivity.
Set the interface's input gain so the loudest part of the set stays out of the red. Phosphene reacts to the shape of the music, not its volume, so a clean signal at a moderate level beats a hot one that clips.
Option 3: DJ software on the same laptop
When the music plays through the computer's own sound output, a free virtual audio cable can hand a copy to Phosphene:
- Mac: install BlackHole (free) and, in Audio MIDI Setup, create a Multi-Output Device that includes both your speakers or headphones and BlackHole. Send your DJ software or music app to that device, then choose BlackHole as Phosphene's input. Rogue Amoeba's Loopback (paid) does the same with a simpler interface.
- Windows: install VB-Audio Virtual Cable (free), send the music to CABLE Input and choose CABLE Output as Phosphene's input. To keep hearing it, open the Sound control panel, go to Recording, open CABLE Output's properties and tick Listen to this device.
There's a catch with DJ controllers. Most of them are their own sound card, so the music goes straight from the controller to the speakers and never passes through the computer's output. In that case use the controller's booth or second master output into an audio interface, as in option 2, or fall back to the mic.
Running visuals and DJ software on one machine also shares the processor and graphics. Phosphene lowers its own render resolution when the frame rate drops, but if your DJ software ever stutters, close Phosphene first. For anything that matters, a second computer for the visuals is the safe choice.
Lock to the tempo
Phosphene listens for the beat and works out the BPM on its own, then keeps a beat clock running between the hits. That clock is what makes the show feel tight: transitions, the strobe, autoplay and launch quantize all follow it.
- Tap tempo. If the detected tempo is off, or doubled or halved, tap T four or more times on the beat. The BPM readout is in the VJ tab under Tap Tempo.
- Sync to the beat clock. Under Tap Tempo, turn on Sync visuals to beat clock and Sync pulse & color to tempo so motion and color changes ride the tempo rather than just the loudness.
- Launch quantize. Set it to Beat or Bar and every engine, scene or Look change waits for the next beat or bar. A slightly late press still lands on the one.
- Transition length. In Transitions, set the length to 1 beat, 2 beats, or 1, 2 or 4 bars, so blends between scenes are timed to the music.
When the DJ changes tempo between tracks, tap it in again as the new track settles.
Put the visuals on the screen
- Connect the projector or screen as a second display, set to extend the desktop rather than mirror it. Use its native resolution, usually 1920 × 1080.
- Press O to open the output window: the visuals alone, with no controls. If nothing appears, allow pop-ups for beautifulengine.com.
- Drag the output window onto the projector and make it full screen: the green button or Control-Command-F on a Mac, F11 on Windows.
- Keep the controls on your laptop. Leave Phosphene's main window open and visible there. If it's minimized or completely covered, the browser can pause it, and the output freezes with it.
The output window runs at 30 frames per second. For the smoothest picture, you can instead drag Phosphene's main window onto the projector, press F for full screen and H to hide the panel, and run the set from the keyboard or a MIDI controller.
DJ mixer REC or booth output
│ RCA to jack
▼
Audio interface line input, USB to the laptop
▼
Phosphene Chrome or Edge on your laptop
│ output window, press O
▼
Projector or screen
To put visuals on a booth front, a row of panels or a backdrop instead of one flat screen, use the built-in mapper. The projection mapping guide covers DJ booths in particular.
Build the night before you play
An hour of preparation at home makes the set far easier to run.
- Collect your scenes. Browse the presets, adjust the ones you like, and save them. Note which engines suit which part of the night: slow, soft ones for the opener, and hard, fast ones for the peak. The engine guide has notes on each.
- Match Beat Mapping to the music. In the Audio tab, Beat Mapping sets how bass, mids and treble move the picture. Heavy Bass suits house, techno and bass music, Melodic suits melodic sets, and Hyperactive suits fast, busy genres. The sliders below fine-tune it.
- Make a cue list. In Setlist · Cue List, add scenes in order and give each a length in bars. With a tempo set, cues change on the bar, and N jumps to the next one.
- Load the decks. Capture two contrasting scenes to Deck A and Deck B, so you can crossfade between them at a drop.
- Set up autoplay for long stretches. Autoplay cycles through scenes on its own, and Drift changes everything slowly. Together they carry a three-hour night while you watch the room.
Play it live
| Key | What it does |
|---|---|
| T | Tap tempo |
| B (hold) | Blackout, for the moment before a drop |
| X (hold) | Strobe, synced to the tempo if you choose |
| G | Freeze the frame while you change things underneath |
| N | Next cue |
| Q / W | Previous / next preset |
| 1–9, 0, -, = | Switch engines |
| A / D | Autoplay / Drift on or off |
| Z | Undo the last change |
| Click or tap | A tap effect where you click: a drop of oil in Fluid, a particle burst in Flow Particles, a new fractal in the fractal engines |
A MIDI controller makes it feel like an instrument. Plug it in, press Connect MIDI Device in the VJ tab, and knobs and faders (CC 1–18) take over the sliders while pads 36–44 switch engines. Launchpad- and APC-style controllers light up to match. Use Chrome or Edge for MIDI.
You can also run the show from a phone with TouchOSC, or let a webcam pick up the dancers so their movement pushes the visuals around. Both are in the webcam, Kinect and OSC guide.
Go easy on the strobe. Fast, full-screen flashing can trigger seizures in people with photosensitive epilepsy, and some venues limit it. Short bursts on the drops hit harder than a strobe left running anyway.
Before doors
- Laptop on its charger, with sleep, the screen saver and notifications turned off (Do Not Disturb or Focus).
- Phosphene opened once with internet and installed as an app, so a venue with no signal doesn't matter.
- The input tested with the real mixer at a real volume, and Sensitivity set.
- The projector at its native resolution, with its own keystone correction off if you're mapping.
- A spare video adapter and cable, and the laptop mic as a backup input.
- Scenes saved, the cue list built, and Deck A and Deck B loaded.
Troubleshooting
The visuals don't move with the music
Check that the level bar in the Audio tab moves. If it doesn't, the browser is listening to the wrong input: choose the right one at chrome://settings/content/microphone or in your system sound settings, then press Listen to Music Playing again. If it moves but the picture barely reacts, raise Sensitivity or try a stronger Beat Mapping.
It reacts to the crowd more than the music
That's the mic hearing the room. Move the laptop closer to a speaker, or switch to a line feed from the mixer.
The tempo is double or half
Tap T on the beat four or more times to set it yourself.
The output window is black or frozen
Make sure Phosphene's main window is open and not minimized or fully covered. Close the output window and press O again.
It stutters
Plug in the charger, close other tabs and apps, and check that hardware acceleration is on in your browser's settings. Running the projector at 1920 × 1080 rather than 4K also helps a lot.
Questions
Does Phosphene work with Rekordbox, Serato or Traktor?
Yes, with any DJ software or hardware, because it listens to the audio rather than connecting to the software. Use a line feed from the mixer or controller, or a virtual audio cable when the music plays through the computer.
Do I need a second laptop?
Not strictly, but it's the safest choice at a gig. Visuals and DJ software on one machine share its processor and graphics, and a separate laptop with a line feed keeps them out of each other's way.
Can the visuals follow the BPM?
Yes. Phosphene detects the tempo and keeps a beat clock that drives transitions, the strobe, autoplay and launch quantize. Tap T to set the tempo yourself whenever you need to.
Does it work without internet at the venue?
Yes. Open Phosphene once with a connection and install it from your browser, and it runs offline after that.
Is it really free?
Yes. There's no account, no watermark on the live output and nothing to install.
Open PhospheneIt's free, and there's nothing to install.