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/*
* Copyright (c) 2024 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#ifndef MODULES_REMOTE_BITRATE_ESTIMATOR_CONGESTION_CONTROL_FEEDBACK_GENERATOR_H_
#define MODULES_REMOTE_BITRATE_ESTIMATOR_CONGESTION_CONTROL_FEEDBACK_GENERATOR_H_
#include <cstdint>
#include <map>
#include <optional>
#include "api/environment/environment.h"
#include "api/sequence_checker.h"
#include "api/units/data_rate.h"
#include "api/units/data_size.h"
#include "api/units/time_delta.h"
#include "api/units/timestamp.h"
#include "modules/remote_bitrate_estimator/congestion_control_feedback_tracker.h"
#include "modules/remote_bitrate_estimator/rtp_transport_feedback_generator.h"
#include "modules/rtp_rtcp/source/rtp_packet_received.h"
#include "rtc_base/experiments/field_trial_parser.h"
namespace webrtc {
// The class is responsible for generating RTCP feedback packets based on
// incoming media packets. Feedback format will comply with RFC 8888.
// https://datatracker.ietf.org/doc/rfc8888/
// 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.
class CongestionControlFeedbackGenerator
: public RtpTransportFeedbackGenerator {
public:
CongestionControlFeedbackGenerator(
const Environment& env,
RtpTransportFeedbackGenerator::RtcpSender feedback_sender);
~CongestionControlFeedbackGenerator() = default;
void OnReceivedPacket(const RtpPacketReceived& packet) override;
void OnSendBandwidthEstimateChanged(DataRate estimate) override;
TimeDelta Process(Timestamp now) override;
void SetTransportOverhead(DataSize overhead_per_packet) override;
private:
Timestamp NextFeedbackTime() const RTC_RUN_ON(sequence_checker_);
void SendFeedback(Timestamp now) RTC_RUN_ON(sequence_checker_);
void CalculateNextPossibleSendTime(DataSize feedback_size, Timestamp now)
RTC_RUN_ON(sequence_checker_);
const Environment env_;
SequenceChecker sequence_checker_;
const RtcpSender rtcp_sender_;
FieldTrialParameter<TimeDelta> min_time_between_feedback_;
FieldTrialParameter<TimeDelta> max_time_to_wait_for_packet_with_marker_;
FieldTrialParameter<TimeDelta> max_time_between_feedback_;
DataRate max_feedback_rate_ = DataRate::KilobitsPerSec(1000);
DataSize packet_overhead_ = DataSize::Zero();
DataSize send_rate_debt_ = DataSize::Zero();
std::map</*ssrc=*/uint32_t, CongestionControlFeedbackTracker>
feedback_trackers_;
// std::vector<PacketInfo> packets_;
Timestamp last_feedback_sent_time_ = Timestamp::Zero();
std::optional<Timestamp> first_arrival_time_since_feedback_;
bool marker_bit_seen_ = false;
Timestamp next_possible_feedback_send_time_ = Timestamp::Zero();
};
} // namespace webrtc
#endif // MODULES_REMOTE_BITRATE_ESTIMATOR_CONGESTION_CONTROL_FEEDBACK_GENERATOR_H_