Apply perceptual curve to media and emit volume

client/src/audio/volume.ts

@@ -0,0 +1,8 @@
+/** Converts a 0-100 slider value into gain using a perceptual smoothstep curve. */
+export function volumePercentToGain(value: unknown, fallbackPercent: number): number {
+  const raw = Number(value);
+  const normalized = Number.isFinite(raw) ? Math.max(0, Math.min(100, raw)) / 100 : Math.max(0, Math.min(100, fallbackPercent)) / 100;
+  // Smoothstep keeps 0->0, 50->0.5, 100->1 while easing low/high ranges.
+  return normalized * normalized * (3 - 2 * normalized);
+}
+