webrtc/modules/rtp_rtcp/source/ulpfec_generator.h
Erik Språng 421088815f Refactors FEC in preparation for deferred packet generation.
RtpVideoSender now stores fec type and overhead instead of querying the
generator all the time. Setting of protection parameters and asking for
current bitrate is also now handled just by the VideoFecGenerator
instance, instead of going via RtpVideoSender.
Finally, adds method to query for RtpState in VideoFecGenerator
interface. This avoids an ugly cast that would have been even more
trouble after moving fec generation.

For context, see https://webrtc-review.googlesource.com/c/src/+/173708

Bug: webrtc:11340
Change-Id: Ia5e6cd919e71850c9cc5ed5a4f4417338d577162
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/174203
Commit-Queue: Erik Språng <sprang@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#31166}
2020-05-05 13:59:14 +00:00

122 lines
4.4 KiB
C++

/*
* 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 <vector>
#include "modules/include/module_fec_types.h"
#include "modules/rtp_rtcp/source/forward_error_correction.h"
#include "modules/rtp_rtcp/source/video_fec_generator.h"
#include "rtc_base/critical_section.h"
#include "rtc_base/race_checker.h"
#include "rtc_base/rate_statistics.h"
namespace webrtc {
class FlexfecSender;
class UlpfecGenerator : public VideoFecGenerator {
friend class FlexfecSender;
public:
UlpfecGenerator(int red_payload_type, int ulpfec_payload_type, Clock* clock);
~UlpfecGenerator();
FecType GetFecType() const override {
return VideoFecGenerator::FecType::kUlpFec;
}
absl::optional<uint32_t> FecSsrc() override { return absl::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;
absl::optional<RtpState> GetRtpState() override { return absl::nullopt; }
private:
struct Params {
Params();
Params(FecProtectionParams delta_params,
FecProtectionParams keyframe_params);
FecProtectionParams delta_params;
FecProtectionParams keyframe_params;
};
UlpfecGenerator(std::unique_ptr<ForwardErrorCorrection> fec, Clock* clock);
// 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;
const FecProtectionParams& CurrentParams() const;
void ResetState();
const int red_payload_type_;
const int ulpfec_payload_type_;
Clock* const clock_;
rtc::RaceChecker race_checker_;
const std::unique_ptr<ForwardErrorCorrection> fec_
RTC_GUARDED_BY(race_checker_);
ForwardErrorCorrection::PacketList media_packets_
RTC_GUARDED_BY(race_checker_);
absl::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 keyframe_in_process_ RTC_GUARDED_BY(race_checker_);
rtc::CriticalSection crit_;
absl::optional<Params> pending_params_ RTC_GUARDED_BY(crit_);
RateStatistics fec_bitrate_ RTC_GUARDED_BY(crit_);
};
} // namespace webrtc
#endif // MODULES_RTP_RTCP_SOURCE_ULPFEC_GENERATOR_H_