1 files changed, 39 insertions, 0 deletions
diff --git a/public/js/components/voice-level.js b/public/js/components/voice-level.js
new file mode 100644
index 0000000..44e9ccc
--- /dev/null
+++ b/public/js/components/voice-level.js
@@ -0,0 +1,39 @@
+/* global AFRAME */
+// Measures how loud a remote person is talking (0..1) from their incoming voice
+// stream, for lip-sync and the speaking indicator.
+AFRAME.registerComponent('voice-level', {
+  init() {
+    this.level = 0;
+    this.analyser = null;
+    this.samples = null;
+
+    this.onSoundSource = (evt) => {
+      const source = evt.detail.soundSource;
+      if (this.analyser) this.analyser.disconnect();
+      this.analyser = source.context.createAnalyser();
+      this.analyser.fftSize = 512;
+      this.samples = new Uint8Array(this.analyser.fftSize);
+      source.connect(this.analyser);
+    };
+    this.el.addEventListener('sound-source-set', this.onSoundSource);
+  },
+
+  remove() {
+    this.el.removeEventListener('sound-source-set', this.onSoundSource);
+    if (this.analyser) this.analyser.disconnect();
+  },
+
+  tick() {
+    if (!this.analyser) return;
+    this.analyser.getByteTimeDomainData(this.samples);
+    let sum = 0;
+    for (let i = 0; i < this.samples.length; i++) {
+      const v = (this.samples[i] - 128) / 128;
+      sum += v * v;
+    }
+    const rms = Math.sqrt(sum / this.samples.length);
+    const target = Math.min(1, Math.max(0, (rms - 0.012) * 9));
+    // Open quickly, close a little slower, so mouths don't chatter.
+    this.level += (target - this.level) * (target > this.level ? 0.6 : 0.2);
+  },
+});