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1 // Copyright 2013 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef MEDIA_CAST_CONGESTION_CONTROL_CONGESTION_CONTROL_H_ | |
6 #define MEDIA_CAST_CONGESTION_CONTROL_CONGESTION_CONTROL_H_ | |
7 | |
8 #include <deque> | |
9 | |
10 #include "base/basictypes.h" | |
11 #include "base/memory/scoped_ptr.h" | |
12 #include "base/time/tick_clock.h" | |
13 #include "base/time/time.h" | |
14 | |
15 namespace media { | |
16 namespace cast { | |
17 | |
18 class CongestionControl { | |
19 public: | |
20 CongestionControl(base::TickClock* clock, | |
21 uint32 max_bitrate_configured, | |
22 uint32 min_bitrate_configured, | |
23 size_t max_unacked_frames); | |
24 | |
25 virtual ~CongestionControl(); | |
26 | |
27 void UpdateRtt(base::TimeDelta rtt); | |
28 | |
29 // Called when an encoded frame is sent to the transport. | |
30 void SendFrameToTransport(uint32 frame_id, | |
31 size_t frame_size, | |
32 base::TimeTicks when); | |
33 | |
34 // Called when we receive an ACK for a frame. | |
35 void AckFrame(uint32 frame_id, base::TimeTicks when); | |
36 | |
37 // Returns the bitrate we should use for the next frame. | |
38 uint32 GetBitrate(base::TimeTicks playout_time, | |
39 base::TimeDelta playout_delay); | |
40 | |
41 private: | |
42 struct FrameStats { | |
43 FrameStats(); | |
44 // Time this frame was sent to the transport. | |
45 base::TimeTicks sent_time; | |
46 // Time this frame was acked. | |
47 base::TimeTicks ack_time; | |
48 // Size of encoded frame in bits. | |
49 size_t frame_size; | |
50 }; | |
51 | |
52 // Calculate how much "dead air" (idle time) there is between two frames. | |
53 static base::TimeDelta DeadTime(const FrameStats& a, const FrameStats& b); | |
54 // Get the FrameStats for a given |frame_id|. | |
55 // Note: Older FrameStats will be removed automatically. | |
56 FrameStats* GetFrameStats(uint32 frame_id); | |
57 // Calculate a safe bitrate. This is based on how much we've been | |
58 // sending in the past. | |
59 double CalculateSafeBitrate(); | |
60 | |
61 // For a given frame, calculate when it might be acked. | |
62 // (Or return the time it was acked, if it was.) | |
63 base::TimeTicks EstimatedAckTime(uint32 frame_id, double bitrate); | |
64 // Calculate when we start sending the data for a given frame. | |
65 // This is done by calculating when we were done sending the previous | |
66 // frame, but obviously can't be less than |sent_time| (if known). | |
67 base::TimeTicks EstimatedSendingTime(uint32 frame_id, double bitrate); | |
68 | |
69 base::TickClock* const clock_; // Not owned by this class. | |
70 const uint32 max_bitrate_configured_; | |
71 const uint32 min_bitrate_configured_; | |
72 std::deque<FrameStats> frame_stats_; | |
73 uint32 last_frame_stats_; | |
74 uint32 last_acked_frame_; | |
75 uint32 last_encoded_frame_; | |
76 base::TimeDelta rtt_; | |
77 size_t history_size_; | |
78 size_t acked_bits_in_history_; | |
79 base::TimeDelta dead_time_in_history_; | |
80 | |
81 DISALLOW_COPY_AND_ASSIGN(CongestionControl); | |
82 }; | |
83 | |
84 } // namespace cast | |
85 } // namespace media | |
86 | |
87 #endif // MEDIA_CAST_CONGESTION_CONTROL_CONGESTION_CONTROL_H_ | |
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