set limit for maxVideoFrameCacheDuration to 2s.

pkg/sfu/receiver.go

@@ -93,8 +93,22 @@ func WithForwardStats(forwardStats *ForwardStats) ReceiverOpts {
 	}
 }
 
+// maxVideoFrameCacheDuration caps the video frame cache window: a longer cached interval would size
+// the retransmit bucket too aggressively and delay subscriber bootstrap, so requests above it are
+// clamped down.
+const maxVideoFrameCacheDuration = 2 * time.Second
+
 func WithVideoFrameCache(maxDuration time.Duration) ReceiverOpts {
 	return func(w *WebRTCReceiver) *WebRTCReceiver {
+		if maxDuration > maxVideoFrameCacheDuration {
+			w.ReceiverBase.Logger().Infow(
+				"clamping video frame cache duration",
+				"requested", maxDuration,
+				"max", maxVideoFrameCacheDuration,
+			)
+			maxDuration = maxVideoFrameCacheDuration
+		}
+
 		w.ReceiverBase.EnableVideoFrameCache(maxDuration)
 		return w
 	}