silvero-vad-js

Pure-JavaScript SileroVAD v5 inference engine. No WASM, no ONNX Runtime — runs on all browsers with AudioWorklet support. Matches the official silero-vad Python wrapper's output frame-by-frame.

Why this exists

Every JS SileroVAD library depends on onnxruntime-web (WASM). That works on most browsers, but ONNX Runtime WASM has been broken on iOS Safari since iOS 16.4+, silently failing on iPhones. This engine reimplements the model's forward pass in vanilla JS — no WASM dependency at all — so it works everywhere: Chrome, Firefox, Safari (desktop and iOS), and any browser that supports AudioWorklet.

Install

npm install @jorastechnologies/silvero-vad-js

Setup

Copy the runtime assets to your app's public/static directory:

cp node_modules/@jorastechnologies/silvero-vad-js/weights/silero_vad_v5.bin      public/vad/
cp node_modules/@jorastechnologies/silvero-vad-js/weights/silero_vad_v5.manifest.json public/vad/
cp node_modules/@jorastechnologies/silvero-vad-js/src/vad_processor.js            public/vad/

The weight files (~1.2 MB) and AudioWorklet script must be served as static files — they are fetched by the browser at runtime and cannot be inlined into a JS bundle.

Usage

import { VADRecorder } from '@jorastechnologies/silvero-vad-js';

const rec = new VADRecorder({
  weightsBinUrl:      '/vad/silero_vad_v5.bin',
  weightsManifestUrl: '/vad/silero_vad_v5.manifest.json',
  workletUrl:         '/vad/vad_processor.js',
  threshold: 0.5,
  silenceMs: 480,
});
rec.addEventListener('speech-start', () => console.log('speaking'));
rec.addEventListener('speech-end', (e) => sendToSTT(e.detail.audio));
await rec.start();

speech-end carries the accumulated audio as a Float32Array at 16kHz (event.detail.audio + event.detail.sampleRate).

Deploying inside an existing Flask + nginx app

Drop the runtime files into Flask's static folder:

your-flask-app/static/vad/
├── silero_vad_v5.bin              # ~1.2 MB (16kHz-only weights)
├── silero_vad_v5.manifest.json    # ~1 KB
├── vad_processor.js               # AudioWorklet — MUST be same-origin
├── silero_vad.js
├── weights_loader.js
├── ops.js
├── vad_recorder.js
└── index.js

Deploy script:

cp node_modules/@jorastechnologies/silvero-vad-js/src/*.js                        your-flask-app/static/vad/
cp node_modules/@jorastechnologies/silvero-vad-js/weights/silero_vad_v5.bin       your-flask-app/static/vad/
cp node_modules/@jorastechnologies/silvero-vad-js/weights/silero_vad_v5.manifest.json your-flask-app/static/vad/

Template snippet:

<script type="module">
  import { VADRecorder } from "{{ url_for('static', filename='vad/index.js') }}";
  const rec = new VADRecorder({
    weightsBinUrl:      "{{ url_for('static', filename='vad/silero_vad_v5.bin') }}",
    weightsManifestUrl: "{{ url_for('static', filename='vad/silero_vad_v5.manifest.json') }}",
    workletUrl:         "{{ url_for('static', filename='vad/vad_processor.js') }}",
  });
  rec.addEventListener('speech-end', (e) => sendToSTT(e.detail.audio));
  await rec.start();
</script>

nginx checklist

1. .js MIME type — curl -I https://yourdomain/static/vad/vad_processor.js must return Content-Type: application/javascript (or text/javascript). Default mime.types covers this.

2. Long cache on weights:

   location ~* /static/vad/.*\.(bin|json)$ {
       expires 1y;
       add_header Cache-Control "public, immutable";
   }

   On model upgrades, version via query string (silero_vad_v5.bin?v=2) — don't rename the file.

3. Same-origin for the worklet — AudioWorklet refuses cross-origin module loads even with CORS. Serving from /static/vad/ (same origin as the page) is the simplest fix.

iOS Safari requirements

• HTTPS is mandatory — iOS blocks getUserMedia on plain HTTP from non-localhost hosts. Use Caddy + Let's Encrypt, nginx + certbot, or Cloudflare in front of nginx.
• iOS Safari 14.5+ is required for AudioWorklet.
• The AudioContext sample rate will be 48kHz on iOS; Chrome on macOS returns 16kHz when requested. Both work — the engine doesn't care about the source rate because the AudioContext is explicitly constructed at 16kHz and the browser resamples.

Architecture

See docs/ARCHITECTURE.md for the per-layer breakdown of the 16kHz forward pass, including the non-obvious STFT input assembly (prepend 64 context samples, right-reflect by 64, total 640 samples into the STFT conv).

The engine ignores the 8kHz path in the ONNX graph and implements only the 16kHz branch — that's all iPhone audio capture needs.

Development

Contributing or regenerating weights from the ONNX source:

git clone <repo-url> && cd silvero-vad-js
npm install
python3 -m pip install -r scripts/requirements.txt

# One-time: download ONNX model + generate weights + golden fixtures
curl -L -o weights/silero_vad_v5.onnx \
  https://github.com/snakers4/silero-vad/raw/master/src/silero_vad/data/silero_vad.onnx
npm run weights:export
npm run weights:golden

npm test           # run all tests (28 pass)
npm run test:watch # TDD
npm run demo       # http://localhost:8000/examples/index.html

All primitive ops (src/ops.js) are pure functions with unit tests. The integration test (tests/silero_vad.test.js) validates the forward pass against the official silero-vad Python wrapper output within 1e-4 per frame.

Security / supply chain note

Socket.dev flags this package for "network access" because weights_loader.js uses fetch() to load the model weights at runtime. These requests go to URLs you provide (your own static files on your own server) — there are no hardcoded external endpoints, no telemetry, and no outbound calls. This is the same pattern used by pdfjs-dist, sql.js, and other packages that load static assets at runtime.

If you prefer to avoid the fetch() path entirely, use loadWeightsFromBuffers(arrayBuffer, manifest) and supply the data yourself.

License

MIT (matches the SileroVAD model license).