[feat] use original webrtc header defines

src/qos/inter_arrival_delta.h

@@ -0,0 +1,89 @@
+/*
+ *  Copyright (c) 2020 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef MODULES_CONGESTION_CONTROLLER_GOOG_CC_INTER_ARRIVAL_DELTA_H_
+#define MODULES_CONGESTION_CONTROLLER_GOOG_CC_INTER_ARRIVAL_DELTA_H_
+
+#include <cstddef>
+
+#include "api/units/time_delta.h"
+#include "api/units/timestamp.h"
+
+namespace webrtc {
+
+// Helper class to compute the inter-arrival time delta and the size delta
+// between two send bursts. This code is branched from
+// modules/remote_bitrate_estimator/inter_arrival.
+class InterArrivalDelta {
+ public:
+  // After this many packet groups received out of order InterArrival will
+  // reset, assuming that clocks have made a jump.
+  static constexpr int kReorderedResetThreshold = 3;
+  static constexpr TimeDelta kArrivalTimeOffsetThreshold =
+      TimeDelta::Seconds(3);
+
+  // A send time group is defined as all packets with a send time which are at
+  // most send_time_group_length older than the first timestamp in that
+  // group.
+  explicit InterArrivalDelta(TimeDelta send_time_group_length);
+
+  InterArrivalDelta() = delete;
+  InterArrivalDelta(const InterArrivalDelta&) = delete;
+  InterArrivalDelta& operator=(const InterArrivalDelta&) = delete;
+
+  // This function returns true if a delta was computed, or false if the current
+  // group is still incomplete or if only one group has been completed.
+  // `send_time` is the send time.
+  // `arrival_time` is the time at which the packet arrived.
+  // `packet_size` is the size of the packet.
+  // `timestamp_delta` (output) is the computed send time delta.
+  // `arrival_time_delta` (output) is the computed arrival-time delta.
+  // `packet_size_delta` (output) is the computed size delta.
+  bool ComputeDeltas(Timestamp send_time, Timestamp arrival_time,
+                     Timestamp system_time, size_t packet_size,
+                     TimeDelta* send_time_delta, TimeDelta* arrival_time_delta,
+                     int* packet_size_delta);
+
+ private:
+  struct SendTimeGroup {
+    SendTimeGroup()
+        : size(0),
+          first_send_time(Timestamp::MinusInfinity()),
+          send_time(Timestamp::MinusInfinity()),
+          first_arrival(Timestamp::MinusInfinity()),
+          complete_time(Timestamp::MinusInfinity()),
+          last_system_time(Timestamp::MinusInfinity()) {}
+
+    bool IsFirstPacket() const { return complete_time.IsInfinite(); }
+
+    size_t size;
+    Timestamp first_send_time;
+    Timestamp send_time;
+    Timestamp first_arrival;
+    Timestamp complete_time;
+    Timestamp last_system_time;
+  };
+
+  // Returns true if the last packet was the end of the current batch and the
+  // packet with `send_time` is the first of a new batch.
+  bool NewTimestampGroup(Timestamp arrival_time, Timestamp send_time) const;
+
+  bool BelongsToBurst(Timestamp arrival_time, Timestamp send_time) const;
+
+  void Reset();
+
+  const TimeDelta send_time_group_length_;
+  SendTimeGroup current_timestamp_group_;
+  SendTimeGroup prev_timestamp_group_;
+  int num_consecutive_reordered_packets_;
+};
+}  // namespace webrtc
+
+#endif  // MODULES_CONGESTION_CONTROLLER_GOOG_CC_INTER_ARRIVAL_DELTA_H_