feat(player): add silence detection and smart speed to local audio player

client/players/smart-speed/SilenceMap.js

@@ -0,0 +1,61 @@
+class SilenceMap {
+  constructor() {
+    this._regions = []
+  }
+
+  get regionCount() {
+    return this._regions.length
+  }
+
+  getRegions() {
+    return [...this._regions]
+  }
+
+  addRegion(startMs, endMs) {
+    if (typeof startMs !== 'number' || typeof endMs !== 'number') return
+    if (startMs < 0 || endMs < 0) return
+    if (endMs <= startMs) return
+
+    const newRegion = { start: startMs, end: endMs }
+    const merged = []
+    let inserted = false
+
+    for (const region of this._regions) {
+      if (newRegion.start <= region.end + 10 && newRegion.end >= region.start - 10) {
+        newRegion.start = Math.min(newRegion.start, region.start)
+        newRegion.end = Math.max(newRegion.end, region.end)
+      } else if (!inserted && region.start > newRegion.end) {
+        merged.push(newRegion)
+        merged.push(region)
+        inserted = true
+      } else {
+        merged.push(region)
+      }
+    }
+
+    if (!inserted) {
+      merged.push(newRegion)
+    }
+
+    this._regions = merged
+  }
+
+  getCompressedOffset(atTimeMs, ratio) {
+    if (!ratio || ratio <= 1) return 0
+    let saved = 0
+    for (const region of this._regions) {
+      if (atTimeMs <= region.start) break
+      const silenceStart = region.start
+      const silenceEnd = Math.min(region.end, atTimeMs)
+      const silenceDuration = silenceEnd - silenceStart
+      saved += silenceDuration * (1 - 1 / ratio)
+    }
+    return saved
+  }
+
+  reset() {
+    this._regions = []
+  }
+}
+
+module.exports = SilenceMap