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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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