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1 /*
2  *  Copyright (c) 2019 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 API_NETEQ_NETEQ_CONTROLLER_H_
12 #define API_NETEQ_NETEQ_CONTROLLER_H_
13 
14 #include <cstddef>
15 #include <cstdint>
16 
17 #include <functional>
18 #include <memory>
19 
20 #include "absl/types/optional.h"
21 #include "api/neteq/neteq.h"
22 #include "api/neteq/tick_timer.h"
23 #include "system_wrappers/include/clock.h"
24 
25 namespace webrtc {
26 
27 // Decides the actions that NetEq should take. This affects the behavior of the
28 // jitter buffer, and how it reacts to network conditions.
29 // This class will undergo substantial refactoring in the near future, and the
30 // API is expected to undergo significant changes. A target API is given below:
31 //
32 // class NetEqController {
33 //  public:
34 //   // Resets object to a clean state.
35 //   void Reset();
36 //   // Given NetEq status, make a decision.
37 //   Operation GetDecision(NetEqStatus neteq_status);
38 //   // Register every packet received.
39 //   void RegisterPacket(PacketInfo packet_info);
40 //   // Register empty packet.
41 //   void RegisterEmptyPacket();
42 //   // Register a codec switching.
43 //   void CodecSwithed();
44 //   // Sets the sample rate.
45 //   void SetSampleRate(int fs_hz);
46 //   // Sets the packet length in samples.
47 //   void SetPacketLengthSamples();
48 //   // Sets maximum delay.
49 //   void SetMaximumDelay(int delay_ms);
50 //   // Sets mininum delay.
51 //   void SetMinimumDelay(int delay_ms);
52 //   // Sets base mininum delay.
53 //   void SetBaseMinimumDelay(int delay_ms);
54 //   // Gets target buffer level.
55 //   int GetTargetBufferLevelMs() const;
56 //   // Gets filtered buffer level.
57 //   int GetFilteredBufferLevel() const;
58 //   // Gets base minimum delay.
59 //   int GetBaseMinimumDelay() const;
60 // }
61 
62 class NetEqController {
63  public:
64   // This struct is used to create a NetEqController.
65   struct Config {
66     bool allow_time_stretching;
67     bool enable_rtx_handling;
68     int max_packets_in_buffer;
69     int base_min_delay_ms;
70     TickTimer* tick_timer;
71     webrtc::Clock* clock = nullptr;
72   };
73 
74   struct PacketInfo {
75     uint32_t timestamp;
76     bool is_dtx;
77     bool is_cng;
78   };
79 
80   struct PacketBufferInfo {
81     bool dtx_or_cng;
82     size_t num_samples;
83     size_t span_samples;
84     size_t span_samples_no_dtx;
85     size_t num_packets;
86   };
87 
88   struct NetEqStatus {
89     uint32_t target_timestamp;
90     int16_t expand_mutefactor;
91     size_t last_packet_samples;
92     absl::optional<PacketInfo> next_packet;
93     NetEq::Mode last_mode;
94     bool play_dtmf;
95     size_t generated_noise_samples;
96     PacketBufferInfo packet_buffer_info;
97     size_t sync_buffer_samples;
98   };
99 
100   virtual ~NetEqController() = default;
101 
102   // Resets object to a clean state.
103   virtual void Reset() = 0;
104 
105   // Resets parts of the state. Typically done when switching codecs.
106   virtual void SoftReset() = 0;
107 
108   // Given info about the latest received packet, and current jitter buffer
109   // status, returns the operation. |target_timestamp| and |expand_mutefactor|
110   // are provided for reference. |last_packet_samples| is the number of samples
111   // obtained from the last decoded frame. If there is a packet available, it
112   // should be supplied in |packet|. The mode resulting from the last call to
113   // NetEqImpl::GetAudio is supplied in |last_mode|. If there is a DTMF event to
114   // play, |play_dtmf| should be set to true. The output variable
115   // |reset_decoder| will be set to true if a reset is required; otherwise it is
116   // left unchanged (i.e., it can remain true if it was true before the call).
117   virtual NetEq::Operation GetDecision(const NetEqStatus& status,
118                                        bool* reset_decoder) = 0;
119 
120   // Inform NetEqController that an empty packet has arrived.
121   virtual void RegisterEmptyPacket() = 0;
122 
123   // Sets the sample rate and the output block size.
124   virtual void SetSampleRate(int fs_hz, size_t output_size_samples) = 0;
125 
126   // Sets a minimum or maximum delay in millisecond.
127   // Returns true if the delay bound is successfully applied, otherwise false.
128   virtual bool SetMaximumDelay(int delay_ms) = 0;
129   virtual bool SetMinimumDelay(int delay_ms) = 0;
130 
131   // Sets a base minimum delay in milliseconds for packet buffer. The effective
132   // minimum delay can't be lower than base minimum delay, even if a lower value
133   // is set using SetMinimumDelay.
134   // Returns true if the base minimum is successfully applied, otherwise false.
135   virtual bool SetBaseMinimumDelay(int delay_ms) = 0;
136   virtual int GetBaseMinimumDelay() const = 0;
137 
138   // These methods test the |cng_state_| for different conditions.
139   virtual bool CngRfc3389On() const = 0;
140   virtual bool CngOff() const = 0;
141 
142   // Resets the |cng_state_| to kCngOff.
143   virtual void SetCngOff() = 0;
144 
145   // Reports back to DecisionLogic whether the decision to do expand remains or
146   // not. Note that this is necessary, since an expand decision can be changed
147   // to kNormal in NetEqImpl::GetDecision if there is still enough data in the
148   // sync buffer.
149   virtual void ExpandDecision(NetEq::Operation operation) = 0;
150 
151   // Adds |value| to |sample_memory_|.
152   virtual void AddSampleMemory(int32_t value) = 0;
153 
154   // Returns the target buffer level in ms.
155   virtual int TargetLevelMs() = 0;
156 
157   // Notify the NetEqController that a packet has arrived. Returns the relative
158   // arrival delay, if it can be computed.
159   virtual absl::optional<int> PacketArrived(bool last_cng_or_dtmf,
160                                             size_t packet_length_samples,
161                                             bool should_update_stats,
162                                             uint16_t main_sequence_number,
163                                             uint32_t main_timestamp,
164                                             int fs_hz) = 0;
165 
166   // Returns true if a peak was found.
167   virtual bool PeakFound() const = 0;
168 
169   // Get the filtered buffer level in samples.
170   virtual int GetFilteredBufferLevel() const = 0;
171 
172   // Accessors and mutators.
173   virtual void set_sample_memory(int32_t value) = 0;
174   virtual size_t noise_fast_forward() const = 0;
175   virtual size_t packet_length_samples() const = 0;
176   virtual void set_packet_length_samples(size_t value) = 0;
177   virtual void set_prev_time_scale(bool value) = 0;
178 };
179 
180 }  // namespace webrtc
181 #endif  // API_NETEQ_NETEQ_CONTROLLER_H_
182