ZLMediaKit/webrtc/Nack.h
2023-03-03 22:13:59 +08:00

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/*
* Copyright (c) 2016 The ZLMediaKit project authors. All Rights Reserved.
*
* This file is part of ZLMediaKit(https://github.com/ZLMediaKit/ZLMediaKit).
*
* Use of this source code is governed by MIT license that can be found in the
* LICENSE file in the root of the source tree. All contributing project authors
* may be found in the AUTHORS file in the root of the source tree.
*/
#ifndef ZLMEDIAKIT_NACK_H
#define ZLMEDIAKIT_NACK_H
#include <set>
#include <map>
#include <deque>
#include <unordered_map>
#include "Rtsp/Rtsp.h"
#include "Rtcp/RtcpFCI.h"
namespace mediakit {
class NackList {
public:
NackList() = default;
~NackList() = default;
void pushBack(RtpPacket::Ptr rtp);
void forEach(const FCI_NACK &nack, const std::function<void(const RtpPacket::Ptr &rtp)> &cb);
private:
void popFront();
uint32_t getCacheMS();
int64_t getRtpStamp(uint16_t seq);
RtpPacket::Ptr *getRtp(uint16_t seq);
private:
uint32_t _cache_ms_check = 0;
std::deque<uint16_t> _nack_cache_seq;
std::unordered_map<uint16_t, RtpPacket::Ptr> _nack_cache_pkt;
};
class NackContext {
public:
using Ptr = std::shared_ptr<NackContext>;
using onNack = std::function<void(const FCI_NACK &nack)>;
//最大保留的rtp丢包状态个数
static constexpr auto kNackMaxSize = 2048;
// rtp丢包状态最长保留时间
static constexpr auto kNackMaxMS = 3 * 1000;
// nack最多请求重传10次
static constexpr auto kNackMaxCount = 10;
// nack重传频率rtt的倍数
static constexpr auto kNackIntervalRatio = 1.0f;
// nack包中rtp个数减小此值可以让nack包响应更灵敏
static constexpr auto kNackRtpSize = 8;
static_assert(kNackRtpSize >=0 && kNackRtpSize <= FCI_NACK::kBitSize, "NackContext::kNackRtpSize must between 0 and 16");
NackContext();
~NackContext() = default;
void received(uint16_t seq, bool is_rtx = false);
void setOnNack(onNack cb);
uint64_t reSendNack();
private:
void eraseFrontSeq();
void doNack(const FCI_NACK &nack, bool record_nack);
void recordNack(const FCI_NACK &nack);
void clearNackStatus(uint16_t seq);
void makeNack(uint16_t max, bool flush = false);
private:
bool _started = false;
int _rtt = 50;
onNack _cb;
std::set<uint16_t> _seq;
// 最新nack包中的rtp seq值
uint16_t _nack_seq = 0;
struct NackStatus {
uint64_t first_stamp;
uint64_t update_stamp;
int nack_count = 0;
};
std::map<uint16_t /*seq*/, NackStatus> _nack_send_status;
};
} // namespace mediakit
#endif //ZLMEDIAKIT_NACK_H