How do you run a live music visualizer on a projector or second screen?

Set-up in four steps

1. Connect the display. Plug the laptop into the projector or second screen and set it as an extended display (or mirror it if you want to watch the same thing).
2. Open Live mode and choose what it hears. Go to groovalizer.space/live and choose what it listens to. The room uses the microphone; allow it when the browser asks, and pick a USB interface or line input later from the LIVE menu at the bottom right. This computer (desktop Chrome, Edge, Brave or Arc) hears the tab playing the music, or your entire screen with system audio on. On a Mac, system audio needs Chrome 141 or later and macOS 14.2 or later.
3. Go fullscreen on the show display. Drag the browser window onto the projector and click Fullscreen, or press F. The visuals fill the screen with no browser chrome. Esc leaves fullscreen and the set keeps playing. To keep the controls on the laptop, click Output window instead and put that window on the projector.
4. Choose the looks and the pace. Pick all looks, the picture looks, Yours or one of your sets. On a computer, leave Hold on Music to change looks with the song (20 minutes a session free, all night with Pro); or pick 15, 30 or 60 seconds, or Manual to change them yourself. Then pick a Speed from 0.5× to 2×. Shuffle mixes Groovalizer’s own looks with the classic MilkDrop packs.

What it is good for

• Parties and house shows. A projector on a wall, the room’s sound through the laptop mic, presets rotating on their own all night.
• DJ sets. Feed the mixer’s booth output into a USB interface so the visuals follow the actual mix. Hold on Music changes looks on the drops and section changes, or switch them yourself on the transitions.
• Bands and small venues. Beat-reactive backdrops without a lighting rig or a VJ laptop full of software.
• Ambient installs and listening rooms. Make a set of slow, luminous looks, play it, and set Hold to 60 seconds and Speed to 0.5×.

The MilkDrop tradition, without Winamp

Live visuals on a wall while music plays is what MilkDrop was for. Groovalizer runs its open-source successor, projectM, compiled to WebAssembly, so the same preset format (thousands of community .milk presets plus Groovalizer’s own) renders at 60 fps in a browser tab on your GPU. Butterchurn does the playback half of this too; Groovalizer adds its own looks, timed changes that dissolve into each other, and the studio for making a file of it afterwards.

Rendering is entirely local (the GPU in the laptop does the work), but preset files load from the site as they cycle, so keep the tab online and load the page before you start.

Practical tips

• Use Chrome or Edge on a laptop with a discrete GPU for the smoothest frame rate; close other tabs.
• Set the display to the projector’s native resolution rather than scaling a 4K desktop down.
• Watch the bar next to LIVE: it shows what the visuals hear. Auto sensitivity turns a quiet room up within a few seconds. If the visuals still barely move, set Sensitivity to High in the LIVE menu or move the mic nearer the speakers.
• Make a set beforehand, with a couple of calm looks for the quiet parts of the night, and play it in order.
• Live asks the browser to keep the screen on while it plays, so the display shouldn’t sleep in the middle of a set.