1 /*
2  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #ifndef WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_INTER_ARRIVAL_H_
12 #define WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_INTER_ARRIVAL_H_
13 
14 #include <cstddef>
15 
16 #include "webrtc/base/constructormagic.h"
17 #include "webrtc/typedefs.h"
18 
19 namespace webrtc {
20 
21 // Helper class to compute the inter-arrival time delta and the size delta
22 // between two timestamp groups. A timestamp is a 32 bit unsigned number with
23 // a client defined rate.
24 class InterArrival {
25  public:
26   // A timestamp group is defined as all packets with a timestamp which are at
27   // most timestamp_group_length_ticks older than the first timestamp in that
28   // group.
29   InterArrival(uint32_t timestamp_group_length_ticks,
30                double timestamp_to_ms_coeff,
31                bool enable_burst_grouping);
32 
33   // This function returns true if a delta was computed, or false if the current
34   // group is still incomplete or if only one group has been completed.
35   // |timestamp| is the timestamp.
36   // |arrival_time_ms| is the local time at which the packet arrived.
37   // |packet_size| is the size of the packet.
38   // |timestamp_delta| (output) is the computed timestamp delta.
39   // |arrival_time_delta_ms| (output) is the computed arrival-time delta.
40   // |packet_size_delta| (output) is the computed size delta.
41   bool ComputeDeltas(uint32_t timestamp,
42                      int64_t arrival_time_ms,
43                      size_t packet_size,
44                      uint32_t* timestamp_delta,
45                      int64_t* arrival_time_delta_ms,
46                      int* packet_size_delta);
47 
48  private:
49   struct TimestampGroup {
TimestampGroupTimestampGroup50     TimestampGroup()
51         : size(0),
52           first_timestamp(0),
53           timestamp(0),
54           complete_time_ms(-1) {}
55 
IsFirstPacketTimestampGroup56     bool IsFirstPacket() const {
57       return complete_time_ms == -1;
58     }
59 
60     size_t size;
61     uint32_t first_timestamp;
62     uint32_t timestamp;
63     int64_t complete_time_ms;
64   };
65 
66   // Returns true if the packet with timestamp |timestamp| arrived in order.
67   bool PacketInOrder(uint32_t timestamp);
68 
69   // Returns true if the last packet was the end of the current batch and the
70   // packet with |timestamp| is the first of a new batch.
71   bool NewTimestampGroup(int64_t arrival_time_ms, uint32_t timestamp) const;
72 
73   bool BelongsToBurst(int64_t arrival_time_ms, uint32_t timestamp) const;
74 
75   const uint32_t kTimestampGroupLengthTicks;
76   TimestampGroup current_timestamp_group_;
77   TimestampGroup prev_timestamp_group_;
78   double timestamp_to_ms_coeff_;
79   bool burst_grouping_;
80 
81   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(InterArrival);
82 };
83 }  // namespace webrtc
84 
85 #endif  // WEBRTC_MODULES_REMOTE_BITRATE_ESTIMATOR_INTER_ARRIVAL_H_
86