perf: stream propagation working sets

packages/acoustics-core/signal.js

@@ -15,6 +15,31 @@ function sampleAsset(signal, assetBuffers, time) {
   return channel[left] + (rightValue - channel[left]) * fraction;
 }
 
+/**
+ * Return the interval in which an entry can emit non-zero samples according to
+ * its declared duration and, for a non-looping asset, the decoded channel
+ * duration. Sample contents themselves are intentionally not inspected.
+ */
+export function effectiveSignalDurationSeconds(
+  entry,
+  scene,
+  assetBuffers = new Map(),
+) {
+  const declaredDuration = entry.duration ?? scene.duration;
+  const signal = entry.signal;
+  if (signal?.type !== "asset" || signal.loop) return declaredDuration;
+  const asset = assetBuffers.get(signal.assetId);
+  const channel = asset?.channels?.[signal.channel ?? 0];
+  if (
+    !channel ||
+    !(asset.sampleRate > 0) ||
+    !Number.isFinite(asset.sampleRate)
+  ) {
+    return declaredDuration;
+  }
+  return Math.min(declaredDuration, channel.length / asset.sampleRate);
+}
+
 /**
  * Render one signal entry into the scene-sized output buffer.
  *