[](https://www.npmjs.com/package/pleco-xa) [](https://github.com/pleco-xa/pleco-xa/blob/main/VERIFICATION.md) [](https://www.npmjs.com/package/pleco-xa?activeTab=dependencies) [](https://www.npmjs.com/package/pleco-xa) [](https://github.com/pleco-xa/pleco-xa/blob/main/LICENSE) > Browser-native audio analysis for JavaScript — BPM & beat tracking, spectral > features, structural segmentation, and intelligent loop detection. > **Zero dependencies. TypeScript declarations included.** pleco-xa brings musical intelligence to anything that runs JavaScript — the browser, Node, Web Workers, the edge. Tempo and beat tracking; mel / MFCC / chroma / spectral descriptors; structural segmentation; DTW & sequence alignment; effects; pitch tracking; pure-DSP vocal separation; and its signature **loop detection** — with **zero runtime dependencies** and no build step required. 47 CI-gated test suites (420 tests) run on every PR and push to `main`, with loop detection locked against committed golden fixtures on real audio. ## Install ```bash npm install pleco-xa ``` ## Two ways to import **The barrel** — everything, tree-shakeable: ```js import { beat_track, loop, stft, feature } from 'pleco-xa' ``` **Per-namespace subpaths** — pull only the domain you need: ```js import { mfcc, chroma_stft, spectral_centroid } from 'pleco-xa/feature' import { detect } from 'pleco-xa/loop' import { hz_to_note, hz_to_midi } from 'pleco-xa/convert' import { dtw, viterbi } from 'pleco-xa/sequence' ``` TypeScript declarations ship for the barrel and all 19 subpaths — editor autocomplete works out of the box, no `@types/…` package needed. ## Quickstart ```js import { beat_track, loop } from 'pleco-xa' const ctx = new AudioContext() const audio = await ctx.decodeAudioData(await (await fetch('song.mp3')).arrayBuffer()) const y = audio.getChannelData(0) const { tempo, beats } = beat_track(y, audio.sampleRate) const best = await loop.detect(audio, { strategy: 'fast' }) console.log(tempo, best.loopStart, best.loopEnd) ``` In Node, decode a WAV with the built-in `decodeWav` and call the same functions — the analysis API is `(Float32Array, sampleRate)` everywhere. ## Subpaths | Import from | What it gives you | | --- | --- | | `pleco-xa/feature` | mfcc, chroma, melspectrogram, spectral centroid / bandwidth / rolloff / contrast / flatness, rms, zcr | | `pleco-xa/loop` | loop detection — one entry point, four strategies, one honest confidence | | `pleco-xa/convert` | hz ↔ midi ↔ note, time ↔ frames ↔ samples, hz ↔ mel, amplitude ↔ dB | | `pleco-xa/segment` | recurrence matrix, agglomerative & Laplacian segmentation | | `pleco-xa/sequence` | DTW, Viterbi, RQA, event/interval matching | | `pleco-xa/decompose` | HPSS, nn_filter, softmask, fingerprint vocal separation | | `pleco-xa/effects` | time-stretch, pitch-shift, remix, trim, split | | `pleco-xa/filters` | mel & chroma filter banks | | `pleco-xa/bpm` | tempo engine | | `pleco-xa/notation` | note / key / interval / svara notation | | `pleco-xa/recurrence` · `pleco-xa/linalg` · `pleco-xa/cluster` · `pleco-xa/intervals` · `pleco-xa/playback` · `pleco-xa/audioio` · `pleco-xa/file` · `pleco-xa/fileio` · `pleco-xa/io` | recurrence, eigensolvers, k-means, interval theory, playback controllers, codecs, streaming readers, WAV I/O | ## Highlights - **Zero dependencies**, pure ESM — runs in browsers, Node, and Web Workers. - **~89 kB min+gzip** for the entire engine — the `feature` subpath alone under 8 kB. No WASM, no model download. - **TypeScript declarations** for the barrel and all 19 subpaths. - **47 CI-gated test suites** (420 tests) — loop points locked against committed golden fixtures on real audio (±10 ms). - **Loop detection** — the signature feature. - **Real-time** streaming analyzers and a live tempo tier. - **Pure-DSP vocal separation** — no model, no weights, no GPU. ## For AI agents A machine-readable capability map ships with this package: `llms.txt` (package root) — the full function index, per-task routing, contracts, and verified recipes in one skim. The complete guides also ship inside the npm package under `docs/`. Also served at [plecoxa.com/llms.txt](https://plecoxa.com/llms.txt). ## Documentation Full guides, a per-function API reference, and an interactive gallery where every one of 50 demos runs live in your browser: **[plecoxa.com](https://plecoxa.com)**. ## License MIT — created and maintained by [Cameron Brooks](https://github.com/brookcs3). See `NOTICE` for third-party algorithm attributions.