R/PLR calculation - time-based window

webrtc/voice_engine/transport_feedback_packet_loss_tracker.h

Index: webrtc/voice_engine/transport_feedback_packet_loss_tracker.h
diff --git a/webrtc/voice_engine/transport_feedback_packet_loss_tracker.h b/webrtc/voice_engine/transport_feedback_packet_loss_tracker.h
index efd0f81d107a636347805e70b7f7ad84c9a829c0..94cb4ff3131dc2cffc438d7e2a7e11dece062254 100644
--- a/webrtc/voice_engine/transport_feedback_packet_loss_tracker.h
+++ b/webrtc/voice_engine/transport_feedback_packet_loss_tracker.h
@@ -24,17 +24,20 @@ class TransportFeedback;
 
 class TransportFeedbackPacketLossTracker final {
  public:
-  // * Up to |max_acked_packets| latest packet statuses will be used for
-  //   calculating the packet loss metrics.
+  // * |max_window_size_ms| is the time-span of the window's acked part.
+  //   We make sure the TWCC sequence number difference between newest and
+  //   oldest is less than 0x8000, regardless of ack-state, but make sure
+  //   that we only consider up to |max_window_size_ms| of acked data for
+  //   the calculation of the metrics.
   // * PLR (packet-loss-rate) is reliably computable once the statuses of
   //   |plr_min_num_acked_packets| packets are known.
   // * RPLR (recoverable-packet-loss-rate) is reliably computable once the
   //   statuses of |rplr_min_num_acked_pairs| pairs are known.
-  TransportFeedbackPacketLossTracker(size_t max_acked_packets,
+  TransportFeedbackPacketLossTracker(int64_t max_window_size_ms,
                                      size_t plr_min_num_acked_packets,
                                      size_t rplr_min_num_acked_pairs);
 
-  void OnPacketAdded(uint16_t seq_num);
+  void OnPacketAdded(uint16_t seq_num, int64_t send_time_ms);
 
   void OnReceivedTransportFeedback(const rtcp::TransportFeedback& feedback);
 
@@ -56,8 +59,14 @@ class TransportFeedbackPacketLossTracker final {
   // metrics accordingly.
 
   enum class PacketStatus { Unacked = 0, Received = 1, Lost = 2 };
-  typedef std::map<uint16_t, PacketStatus> PacketStatusMap;
-  typedef PacketStatusMap::const_iterator ConstPacketStatusIterator;
+  struct SentPacket {
+    SentPacket(int64_t send_time_ms, PacketStatus status)
+        : send_time_ms(send_time_ms), status(status) {}
+    int64_t send_time_ms;
+    PacketStatus status;
+  };
+  typedef std::map<uint16_t, SentPacket> SentPacketStatusMap;
+  typedef SentPacketStatusMap::const_iterator ConstPacketStatusIterator;
 
   void Reset();
 
@@ -68,7 +77,8 @@ class TransportFeedbackPacketLossTracker final {
   // |packet_status_window_|.
   uint16_t ReferenceSequenceNumber() const;
   uint16_t NewestSequenceNumber() const;
-  void RecordFeedback(PacketStatusMap::iterator it, bool received);
+  void RecordPacketStatus(SentPacketStatusMap::iterator it,
+                          PacketStatus new_packet_status);
   void RemoveOldestPacketStatus();
 
   void UpdateMetrics(ConstPacketStatusIterator it,
@@ -81,10 +91,10 @@ class TransportFeedbackPacketLossTracker final {
   ConstPacketStatusIterator NextPacketStatus(
       ConstPacketStatusIterator it) const;
 
-  const size_t max_acked_packets_;
+  const int64_t max_window_size_ms_;
   size_t acked_packets_;
 
-  PacketStatusMap packet_status_window_;
+  SentPacketStatusMap packet_status_window_;
   // |ref_packet_status_| points to the oldest item in |packet_status_window_|.
   ConstPacketStatusIterator ref_packet_status_;