Music that never stops, and your own beat pieces arranged into new songs. Everything runs on the phone; no sound is uploaded. Part of Orbit, a family of apps for life in Taiwan that share one sign-in, the Orbit Pass. See them all at orbit.jaypengx.com.
Features
- 用說的做節奏: say what you'd like to hear over 電台 (讀書用的 lo-fi); code reads it into grooves, a scene and a tempo, and only words code can't place go to AI, which never touches sound.
- Plays nicely: another app's sound stops Beats, and nothing restarts it but your tap. Songs made on the app's own band sync to every phone through the Pass, as recipes.
- 聽 Listen: one play button and a mood (relaxed, energetic, groovy, classic, or one groove). Each song is written on the spot: a groove, tempo, key, chords, melodies, bass and drums, arranged into verses, hooks and a bridge and mixed, about two and a half minutes. It plays on with the screen locked, one song running into the next with no gap.
- 今日精選 and 今日挑戰 are the same on every phone, made from Taiwan's date alone; 為你推薦, 為你電台 and 做歌 learn from what you listen to the end and what you skip.
- 即興 Jam: 16 coloured pads of a built-in band over a groove, or your own pieces as pads; record a take and it becomes a song.
- 樂器 Instruments: a step grid of drums or notes on 42 instruments and 32 drum lanes, with accents, chords, swing, tap tempo, up to four sections chained, and MIDI out.
- 做歌 Make songs: your recordings, a sample pack or the microphone, split on silences, and a long take with none cut on its beat (its bars, or hit by hit); the tempo, the role of each piece (riff, bass, hats, kick, 808…) and the key heard automatically; then full songs arranged in a real song form, each piece exactly as recorded.
- 節奏遊戲 Rhythm game: every song is a level, its chart taken from the song's own notes, four lanes, four difficulties, playable with two thumbs.
- 資料庫 Library: keep songs small (AAC), playlists, search, and export as WAV, stems, MIDI or a zip.
- 簡單 / 進階: Simple mode for everyone, Advanced for every control, and 23 music words explained in everyday language.
- Private: everything runs on the phone; no sound is ever uploaded.
- Every screen, either way up: on a tablet, a computer or a phone on its side 首頁's shelves widen, 創作's 即興 sits beside the rhythm game and 樂器·做歌, and 資料庫's rows beside its covers.
Tech stack
| Layer | What |
|---|
| App | Plain JavaScript (ES modules), HTML and CSS; no framework, no build step, no dependencies |
| Audio | Synthesis and mixing in Web Workers, Web Audio, Media Source with WebCodecs' AudioEncoder (FLAC, AAC or Opus in MP4) for gapless play, one <audio> for the lock screen |
| Sounds | 32 recorded instruments (a real string section from VSCO 2, the Salamander grand piano, the rest from the MusyngKite soundfont), recorded drum kits (acoustic, TR-808, electronic, hand percussion), plus band-limited synth voices |
| Storage | IndexedDB for kept songs and kits on the phone; only settings go to the Orbit Pass |
| Shared | Look and Orbit Pass from the kit in Orbit-Core |
| Command line | passion_beats.py (Python 3, NumPy, SciPy): the same engine, kept in step with engine.mjs |
| Tests | node --test on the engine, the mix, variety, loudness and playability |
How it works
pieces in (files, pack, mic) ─► split on silence, then the beat (rhythm.mjs) ─► tempo · roles · key (analyze.mjs)
│
built-in band (radio.mjs) ─────────────────────────────► engine.mjs: song form, phrases, fills
│
▼
mix.mjs: buses, glue, room, loudness, limiter (in a worker)
│
▼
player · library · WAV / stems / MIDI
- Tempo: every tempo from 70 to 190 BPM is scored by how well the hits sit on 16ths; on 100 made-up packs, 97% of tempos and 97.5% of roles come out right.
- Variety by rule: the next song never repeats a groove from the last six, jumps tempo or feel, and changes key, chords, lead and form; tests check 30 songs per mood.
- Never silent by accident: no quarter second of a radio song falls under -45 dBFS; the tests listen to twenty back to back.
The engine, the sounds and the decisions still in force: MAP.md.
Project structure
public/
├── index.html, app.js the page, tabs, player, library
├── engine.mjs song planning and rendering (port of passion_beats.py)
├── analyze.mjs hearing tempo and roles
├── lib/ 46 modules: radio, synth, voices, samples, mix, jam,
│ studio, game, library, playlists, cover, tape, help
├── samples/ recorded instruments (mk/) and drum kits (drums/)
└── sw.js
passion_beats.py the same engine on the command line
scripts/ samples, drums, listen, loudness
tests/ node --test
MAP.md how it works
Getting started
The app loads the shared kit from a sibling folder, so clone this repo next to Orbit-Core:
git clone https://github.com/JayPengX/Orbit-Core.git
git clone https://github.com/JayPengX/Orbit-Beats.git
cd Orbit-Beats
Requirements: Node.js 22 or newer. There is nothing to install: no framework, no node_modules.
npm test # links ../Orbit-Core/kit as .kit, then runs node --test
See it on a phone-sized screen, signed in with a made-up wallet and real data (needs Playwright):
This is the beginning of the README. Read the rest at the original. Read the full README ↗
