Median filter

webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc

Index: webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc b/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
index 2500679343a52c37da87f6ec6ff4fc59e0e225fe..e5ab69fc16913ba7b151fbd056a8166e9547fd55 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
@@ -124,12 +124,21 @@ FeedbackPacket* NadaBweReceiver::GetFeedback(int64_t now_ms) {
                           derivative, RecentKbps(), corrected_send_time_ms);
 }
 
+// If size is even, the median will be the average of the two middlemost
+// numbers.
 int64_t NadaBweReceiver::MedianFilter(int64_t* last_delays_ms, int size) {
-  // Typically, size = 5.
   std::vector<int64_t> array_copy(last_delays_ms, last_delays_ms + size);
   std::nth_element(array_copy.begin(), array_copy.begin() + size / 2,
                    array_copy.end());

[stefan-webrtc, 2015/07/22 09:21:19]

Move this inside the if statement.

-  return array_copy.at(size / 2);
+  // Typically, size = 5. For odd size values, right and left are equal.
+  if (size % 2 == 1) {

[magalhaesc, 2015/07/22 09:01:11]

This "if" statement isn't necessary here. But it avoids unnecessary nth_element
computations (since currently nearly all calls use size = 5).

+    return array_copy.at(size / 2);
+  }
+  int64_t right = array_copy.at(size / 2);
+  std::nth_element(array_copy.begin(), array_copy.begin() + (size - 1) / 2,
+                   array_copy.end());
+  int64_t left = array_copy.at((size - 1) / 2);
+  return (left + right + 1) / 2;
 }
 
 int64_t NadaBweReceiver::ExponentialSmoothingFilter(int64_t new_value,