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/*
* Copyright (c) 2012 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_RTP_RTCP_SOURCE_ULPFEC_GENERATOR_H_
#define MODULES_RTP_RTCP_SOURCE_ULPFEC_GENERATOR_H_
#include <stddef.h>
#include <stdint.h>
#include <list>
#include <memory>
#include <optional>
#include <vector>
#include "api/environment/environment.h"
#include "api/units/data_rate.h"
#include "modules/include/module_fec_types.h"
#include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
#include "modules/rtp_rtcp/source/forward_error_correction.h"
#include "modules/rtp_rtcp/source/rtp_packet_to_send.h"
#include "modules/rtp_rtcp/source/video_fec_generator.h"
#include "rtc_base/bitrate_tracker.h"
#include "rtc_base/race_checker.h"
#include "rtc_base/synchronization/mutex.h"
#include "rtc_base/thread_annotations.h"
namespace webrtc {
class FlexfecSender;
class UlpfecGenerator : public VideoFecGenerator {
friend class FlexfecSender;
public:
UlpfecGenerator(const Environment& env,
int red_payload_type,
int ulpfec_payload_type);
~UlpfecGenerator();
FecType GetFecType() const override {
return VideoFecGenerator::FecType::kUlpFec;
}
std::optional<uint32_t> FecSsrc() override { return std::nullopt; }
void SetProtectionParameters(const FecProtectionParams& delta_params,
const FecProtectionParams& key_params) override;
// Adds a media packet to the internal buffer. When enough media packets
// have been added, the FEC packets are generated and stored internally.
// These FEC packets are then obtained by calling GetFecPacketsAsRed().
void AddPacketAndGenerateFec(const RtpPacketToSend& packet) override;
// Returns the overhead, per packet, for FEC (and possibly RED).
size_t MaxPacketOverhead() const override;
std::vector<std::unique_ptr<RtpPacketToSend>> GetFecPackets() override;
// Current rate of FEC packets generated, including all RTP-level headers.
DataRate CurrentFecRate() const override;
std::optional<RtpState> GetRtpState() override { return std::nullopt; }
// Currently used protection params.
const FecProtectionParams& CurrentParams() const;
private:
struct Params {
Params();
Params(FecProtectionParams delta_params,
FecProtectionParams keyframe_params);
FecProtectionParams delta_params;
FecProtectionParams keyframe_params;
};
UlpfecGenerator(const Environment& env,
std::unique_ptr<ForwardErrorCorrection> fec);
// Overhead is defined as relative to the number of media packets, and not
// relative to total number of packets. This definition is inherited from the
// protection factor produced by video_coding module and how the FEC
// generation is implemented.
int Overhead() const;
// Returns true if the excess overhead (actual - target) for the FEC is below
// the amount `kMaxExcessOverhead`. This effects the lower protection level
// cases and low number of media packets/frame. The target overhead is given
// by `params_.fec_rate`, and is only achievable in the limit of large number
// of media packets.
bool ExcessOverheadBelowMax() const;
// Returns true if the number of added media packets is at least
// `min_num_media_packets_`. This condition tries to capture the effect
// that, for the same amount of protection/overhead, longer codes
// (e.g. (2k,2m) vs (k,m)) are generally more effective at recovering losses.
bool MinimumMediaPacketsReached() const;
void ResetState();
const Environment env_;
const int red_payload_type_;
const int ulpfec_payload_type_;
RaceChecker race_checker_;
const std::unique_ptr<ForwardErrorCorrection> fec_
RTC_GUARDED_BY(race_checker_);
ForwardErrorCorrection::PacketList media_packets_
RTC_GUARDED_BY(race_checker_);
std::optional<RtpPacketToSend> last_media_packet_
RTC_GUARDED_BY(race_checker_);
std::list<ForwardErrorCorrection::Packet*> generated_fec_packets_
RTC_GUARDED_BY(race_checker_);
int num_protected_frames_ RTC_GUARDED_BY(race_checker_);
int min_num_media_packets_ RTC_GUARDED_BY(race_checker_);
Params current_params_ RTC_GUARDED_BY(race_checker_);
bool media_contains_keyframe_ RTC_GUARDED_BY(race_checker_);
mutable Mutex mutex_;
std::optional<Params> pending_params_ RTC_GUARDED_BY(mutex_);
BitrateTracker fec_bitrate_ RTC_GUARDED_BY(mutex_);
};
} // namespace webrtc
#endif // MODULES_RTP_RTCP_SOURCE_ULPFEC_GENERATOR_H_
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