[feat] update congestion control feedback

src/qos/congestion_control_feedback_generator.h

@@ -0,0 +1,59 @@
+/*
+ * @Author: DI JUNKUN
+ * @Date: 2024-12-18
+ * Copyright (c) 2024 by DI JUNKUN, All Rights Reserved.
+ */
+
+#ifndef _CONGESTION_CONTROL_FEEDBACK_GENERATOR_H_
+#define _CONGESTION_CONTROL_FEEDBACK_GENERATOR_H_
+
+#include "rtp_packet_received.h"
+
+class CongestionControlFeedbackGenerator
+    : public RtpTransportFeedbackGenerator {
+ public:
+  CongestionControlFeedbackGenerator(
+      RtpTransportFeedbackGenerator::RtcpSender feedback_sender);
+  ~CongestionControlFeedbackGenerator() = default;
+
+  void OnReceivedPacket(const RtpPacketReceived& packet) override;
+
+  void OnSendBandwidthEstimateChanged(DataRate estimate) override;
+
+  int64_t Process(int64_t now_ms) override;
+
+  void SetTransportOverhead(DataSize overhead_per_packet) override;
+
+ private:
+  int64_t NextFeedbackTime() const;
+
+  void SendFeedback(int64_t now_ms);
+
+  void CalculateNextPossibleSendTime(int64_t feedback_size, int64_t now_ms);
+
+ private:
+  // Feedback should not use more than 5% of the configured send bandwidth
+  // estimate. Min and max duration between feedback is configurable using field
+  // trials, but per default, min is 25ms and max is 250ms.
+  // If possible, given the other constraints, feedback will be sent when a
+  // packet with marker bit is received in order to provide feedback as soon as
+  // possible after receiving a complete video frame. If no packet with marker
+  // bit is received, feedback can be delayed up to 25ms after the first packet
+  // since the last sent feedback. On good networks, this means that a sender
+  // may receive feedback for every sent frame.
+  int64_t min_time_between_feedback_ = 25;
+  int64_t max_time_between_feedback_ = 250;
+  int64_t max_time_to_wait_for_packet_with_marker_ = 25;
+
+  int64_t max_feedback_rate_ = 1000;  // kbps
+  int64_t packet_overhead_ = 0;
+  int64_t send_rate_debt_ = 0;
+
+  std::optional<int64_t> first_arrival_time_since_feedback_;
+  int64_t next_possible_feedback_send_time_ = 0;
+  int64_t last_feedback_sent_time_ = 0;
+
+  bool marker_bit_seen_ = false;
+};
+
+#endif