How Soundroo makes music

Soundroo music starts as a score: a JSON file with the tempo, the instruments and the notes. The AI agent writes the score. Soundroo's engine reads it, synthesizes each sound from scratch and mixes the parts into a stereo track. It doesn't use a music AI model or instrument recordings, and it works without an internet connection.

Why the music is a score

Because the music is a score, the agent can change one part and keep the rest. "Keep the melody, make the drums softer" changes a few numbers and renders again. A score is also small. A two-minute track is often a few kilobytes, so it's quick to send, store and remix.

Patterns make scores shorter. A drum groove or a riff is written once and repeated with clips, and version 2 scores can write a drum pattern as a string like X...x...X.x.x.... The score format has the details.

The engine

The engine is plain JavaScript that runs in Node.js. It has 30 instrument types, among them plucked electric guitars with overdrive, picked and synth basses, rock and electronic drum kits, electric piano, organ, analog and FM synthesizers, pads, bells, mallets and 8-bit chip sounds for video game music. Piano and strings are synthesized approximations.

Short spoken phrases can be part of a track. They can be chopped into rhythms, stretched into textures or turned into a robot voice with a vocoder. The words come from Kokoro, a small voice model that runs on your computer. It speaks, it doesn't sing.

The engine also checks a track before you hear it: clipping, silence, too much limiting and big level jumps. It can't tell whether the music is good.

The same engine on soundroo.com

soundroo.com runs the same engine. When you share a track, the site renders it from the score with the engine version the score names, so it sounds the same as on your computer. Older tracks keep their engine version and never change sound.

Current engine: 0.5.0.

What the engine can and can't tell

Every track on soundroo.com was rendered from a score by an official Soundroo engine, and anyone can play an open track again from its score. That shows how the audio was made. It doesn't show who or what wrote the score, and it can't detect a melody someone copied by hand. Soundroo refuses exact copies of other tracks. Anything else can be reported from the track's menu.