P4

daemon/vad.js

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+import { EventEmitter } from 'node:events';
+import { pcmRms } from './audio-pipewire.js';
+
+export const DEFAULT_VAD = Object.freeze({
+  threshold: 0.6,
+  minSpeechDurationMs: 300,
+  minSilenceDurationMs: 700,
+  maxSpeechDurationMs: 15_000,
+  speechPadMs: 200,
+});
+
+/** A conservative local gate around QVAC's stream. It bounds audio sent to
+ * ASR and gives the loop deterministic utterance boundaries in tests. */
+export class VadSegmenter extends EventEmitter {
+  constructor({ sampleRate = 16_000, frameMs = 20, params = {} } = {}) {
+    super();
+    this.sampleRate = sampleRate;
+    this.frameMs = frameMs;
+    this.params = { ...DEFAULT_VAD, ...params };
+    this.reset();
+  }
+
+  reset() { this.speaking = false; this.buffer = []; this.speechMs = 0; this.silenceMs = 0; }
+
+  push(frame) {
+    const chunk = Buffer.from(frame || '');
+    const rms = pcmRms(chunk);
+    const voiced = rms >= this.params.threshold / 10; // PCM RMS is 0..1; QVAC threshold is posterior-like.
+    this.emit('level', rms);
+    if (!this.speaking && voiced) {
+      this.speaking = true; this.speechMs = 0; this.silenceMs = 0; this.buffer = [];
+      this.emit('speechStart');
+    }
+    if (!this.speaking) return;
+    this.buffer.push(chunk);
+    if (voiced) { this.speechMs += this.frameMs; this.silenceMs = 0; }
+    else { this.silenceMs += this.frameMs; }
+    if (this.speechMs >= this.params.maxSpeechDurationMs ||
+        (this.speechMs >= this.params.minSpeechDurationMs && this.silenceMs >= this.params.minSilenceDurationMs)) {
+      this.end();
+    }
+  }
+
+  end() {
+    if (!this.speaking) return null;
+    const audio = Buffer.concat(this.buffer);
+    this.reset();
+    this.emit('utterance', audio);
+    return audio;
+  }
+}