mirror of
https://github.com/ZLMediaKit/ZLMediaKit.git
synced 2024-11-23 11:17:09 +08:00
380 lines
14 KiB
C++
380 lines
14 KiB
C++
/*
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* Copyright (c) 2016-present The ZLMediaKit project authors. All Rights Reserved.
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*
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* This file is part of ZLMediaKit(https://github.com/ZLMediaKit/ZLMediaKit).
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*
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* Use of this source code is governed by MIT-like license that can be found in the
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* LICENSE file in the root of the source tree. All contributing project authors
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* may be found in the AUTHORS file in the root of the source tree.
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*/
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#include "Nack.h"
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#include "Common/config.h"
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using namespace std;
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using namespace toolkit;
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namespace mediakit {
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// RTC配置项目 [AUTO-TRANSLATED:19940011]
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// RTC configuration project
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namespace Rtc {
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#define RTC_FIELD "rtc."
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// ~ nack接收端, rtp发送端 [AUTO-TRANSLATED:e1065811]
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// ~ nack receiver, rtp sender
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// rtp重发缓存列队最大长度，单位毫秒 [AUTO-TRANSLATED:80bccd26]
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// rtp retransmission cache queue maximum length, in milliseconds
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const string kMaxRtpCacheMS = RTC_FIELD "maxRtpCacheMS";
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// rtp重发缓存列队最大长度，单位个数 [AUTO-TRANSLATED:7d710bf5]
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// rtp retransmission cache queue maximum length, in number
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const string kMaxRtpCacheSize = RTC_FIELD "maxRtpCacheSize";
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// ~ nack发送端，rtp接收端 [AUTO-TRANSLATED:bb169205]
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// ~ nack sender, rtp receiver
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// 最大保留的rtp丢包状态个数 [AUTO-TRANSLATED:3aeb53f8]
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// Maximum number of rtp packet loss states to keep
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const string kNackMaxSize = RTC_FIELD "nackMaxSize";
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// rtp丢包状态最长保留时间 [AUTO-TRANSLATED:f9306375]
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// Maximum retention time for rtp packet loss state
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const string kNackMaxMS = RTC_FIELD "nackMaxMS";
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// nack最多请求重传次数 [AUTO-TRANSLATED:300be0d0]
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// Maximum number of nack retransmission requests
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const string kNackMaxCount = RTC_FIELD "nackMaxCount";
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// nack重传频率，rtt的倍数 [AUTO-TRANSLATED:924d53d2]
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// Nack retransmission frequency, multiple of rtt
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const string kNackIntervalRatio = RTC_FIELD "nackIntervalRatio";
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// nack包中rtp个数，减小此值可以让nack包响应更灵敏 [AUTO-TRANSLATED:12393868]
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// Number of rtp in nack packet, reducing this value can make nack packet response more sensitive
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const string kNackRtpSize = RTC_FIELD "nackRtpSize";
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static onceToken token([]() {
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mINI::Instance()[kMaxRtpCacheMS] = 5 * 1000;
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mINI::Instance()[kMaxRtpCacheSize] = 2048;
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mINI::Instance()[kNackMaxSize] = 2048;
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mINI::Instance()[kNackMaxMS] = 3 * 1000;
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mINI::Instance()[kNackMaxCount] = 15;
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mINI::Instance()[kNackIntervalRatio] = 1.0f;
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mINI::Instance()[kNackRtpSize] = 8;
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});
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} // namespace Rtc
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void NackList::pushBack(RtpPacket::Ptr rtp) {
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GET_CONFIG(uint32_t, max_rtp_cache_ms, Rtc::kMaxRtpCacheMS);
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GET_CONFIG(uint32_t, max_rtp_cache_size, Rtc::kMaxRtpCacheSize);
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// 记录rtp [AUTO-TRANSLATED:f08e12e2]
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// Record rtp
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auto seq = rtp->getSeq();
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_nack_cache_seq.emplace_back(seq);
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_nack_cache_pkt.emplace(seq, std::move(rtp));
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// 限制rtp缓存最大个数 [AUTO-TRANSLATED:a6bb50f5]
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// Limit the maximum number of rtp cache
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if (_nack_cache_seq.size() > max_rtp_cache_size) {
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popFront();
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}
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if (++_cache_ms_check < 100) {
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// 每100个rtp包检测下缓存长度，节省cpu资源 [AUTO-TRANSLATED:6399c705]
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// Check the cache length every 100 rtp packets to save cpu resources
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return;
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}
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_cache_ms_check = 0;
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// 限制rtp缓存最大时长 [AUTO-TRANSLATED:83e5be93]
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// Limit the maximum duration of rtp cache
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while (getCacheMS() >= max_rtp_cache_ms) {
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popFront();
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}
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}
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void NackList::forEach(const FCI_NACK &nack, const function<void(const RtpPacket::Ptr &rtp)> &func) {
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auto seq = nack.getPid();
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for (auto bit : nack.getBitArray()) {
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if (bit) {
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// 丢包 [AUTO-TRANSLATED:ac2c9d55]
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// Packet loss
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RtpPacket::Ptr *ptr = getRtp(seq);
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if (ptr) {
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func(*ptr);
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}
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}
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++seq;
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}
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}
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void NackList::popFront() {
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if (_nack_cache_seq.empty()) {
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return;
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}
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_nack_cache_pkt.erase(_nack_cache_seq.front());
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_nack_cache_seq.pop_front();
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}
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RtpPacket::Ptr *NackList::getRtp(uint16_t seq) {
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auto it = _nack_cache_pkt.find(seq);
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if (it == _nack_cache_pkt.end()) {
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return nullptr;
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}
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return &it->second;
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}
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uint32_t NackList::getCacheMS() {
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while (_nack_cache_seq.size() > 2) {
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auto back_stamp = getNtpStamp(_nack_cache_seq.back());
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if (back_stamp == -1) {
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_nack_cache_seq.pop_back();
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continue;
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}
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auto front_stamp = getNtpStamp(_nack_cache_seq.front());
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if (front_stamp == -1) {
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_nack_cache_seq.pop_front();
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continue;
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}
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if (back_stamp >= front_stamp) {
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return back_stamp - front_stamp;
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}
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// ntp时间戳回退了，非法数据，丢掉 [AUTO-TRANSLATED:79ddf252]
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// Ntp timestamp has been rolled back, illegal data, discard
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_nack_cache_seq.pop_front();
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}
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return 0;
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}
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int64_t NackList::getNtpStamp(uint16_t seq) {
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auto it = _nack_cache_pkt.find(seq);
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if (it == _nack_cache_pkt.end()) {
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return -1;
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}
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// 使用ntp时间戳，不会回退 [AUTO-TRANSLATED:2d509f8f]
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// Use ntp timestamp, will not roll back
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return it->second->getStampMS(true);
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}
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////////////////////////////////////////////////////////////////////////////////////////////////
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NackContext::NackContext() {
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setOnNack(nullptr);
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}
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void NackContext::received(uint16_t seq, bool is_rtx) {
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if (!_started) {
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// 记录第一个seq [AUTO-TRANSLATED:410c831f]
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// Record the first seq
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_started = true;
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_nack_seq = seq - 1;
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}
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if (seq < _nack_seq && _nack_seq != UINT16_MAX && seq < 1024 && _nack_seq > UINT16_MAX - 1024) {
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// seq回环,清空回环前状态 [AUTO-TRANSLATED:4cb8027e]
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// Seq loop, clear the state before the loop
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makeNack(UINT16_MAX, true);
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_seq.emplace(seq);
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return;
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}
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if (is_rtx || (seq < _nack_seq && _nack_seq != UINT16_MAX)) {
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// seq非回环回退包，猜测其为重传包，清空其nack状态 [AUTO-TRANSLATED:74c7b706]
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// Seq non-loop rollback packet, guess it is a retransmission packet, clear its nack state
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clearNackStatus(seq);
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return;
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}
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auto pr = _seq.emplace(seq);
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if (!pr.second) {
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// seq重复, 忽略 [AUTO-TRANSLATED:95ec10db]
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// Seq duplicate, ignore
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return;
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}
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auto max_seq = *_seq.rbegin();
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auto min_seq = *_seq.begin();
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auto diff = max_seq - min_seq;
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if (diff > (UINT16_MAX >> 1)) {
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// 回环后，收到回环前的大值seq, 忽略掉 [AUTO-TRANSLATED:6a30b91f]
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// After the loop, receive a large seq value before the loop, ignore it
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_seq.erase(max_seq);
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return;
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}
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if (min_seq == (uint16_t)(_nack_seq + 1) && _seq.size() == (size_t)diff + 1) {
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// 都是连续的seq，未丢包 [AUTO-TRANSLATED:62d3ffbd]
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// All are continuous seq, no packet loss
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_seq.clear();
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_nack_seq = max_seq;
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} else {
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// seq不连续，有丢包 [AUTO-TRANSLATED:ba1bfbc2]
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// Seq is not continuous, there is packet loss
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makeNack(max_seq, false);
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}
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}
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void NackContext::makeNack(uint16_t max_seq, bool flush) {
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// 尝试移除前面部分连续的seq [AUTO-TRANSLATED:04593c1b]
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// Try to remove the continuous seq in front
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eraseFrontSeq();
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// 最多生成5个nack包，防止seq大幅跳跃导致一直循环 [AUTO-TRANSLATED:9cc5da25]
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// Generate at most 5 nack packets to prevent seq from jumping significantly and causing continuous loops
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auto max_nack = 5u;
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GET_CONFIG(uint32_t, nack_rtpsize, Rtc::kNackRtpSize);
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// kNackRtpSize must between 0 and 16
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nack_rtpsize = std::min<uint32_t>(nack_rtpsize, FCI_NACK::kBitSize);
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while (_nack_seq != max_seq && max_nack--) {
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// 一次不能发送超过16+1个rtp的状态 [AUTO-TRANSLATED:1954831a]
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// Cannot send more than 16+1 rtp states at a time
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uint16_t nack_rtp_count = std::min<uint16_t>(FCI_NACK::kBitSize, max_seq - (uint16_t)(_nack_seq + 1));
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if (!flush && nack_rtp_count < nack_rtpsize) {
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// 非flush状态下，seq个数不足以发送一次nack [AUTO-TRANSLATED:94f561c1]
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// In non-flush state, the number of seq is not enough to send a nack
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break;
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}
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vector<bool> vec;
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vec.resize(nack_rtp_count, false);
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for (size_t i = 0; i < nack_rtp_count; ++i) {
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vec[i] = _seq.find((uint16_t)(_nack_seq + i + 2)) == _seq.end();
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}
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doNack(FCI_NACK(_nack_seq + 1, vec), true);
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_nack_seq += nack_rtp_count + 1;
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// 返回第一个比_last_max_seq大的元素 [AUTO-TRANSLATED:425c4e63]
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// Return the first element greater than _last_max_seq
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auto it = _seq.upper_bound(_nack_seq);
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// 移除 <=_last_max_seq 的seq [AUTO-TRANSLATED:a64ff3fd]
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// Remove seq <= _last_max_seq
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_seq.erase(_seq.begin(), it);
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}
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}
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void NackContext::setOnNack(onNack cb) {
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if (cb) {
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_cb = std::move(cb);
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} else {
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_cb = [](const FCI_NACK &nack) {};
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}
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}
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void NackContext::doNack(const FCI_NACK &nack, bool record_nack) {
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if (record_nack) {
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recordNack(nack);
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}
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_cb(nack);
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}
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void NackContext::eraseFrontSeq() {
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// 前面部分seq是连续的，未丢包，移除之 [AUTO-TRANSLATED:ef3eed87]
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// The previous part of the sequence is continuous and has no packet loss, remove it.
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for (auto it = _seq.begin(); it != _seq.end();) {
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if (*it != (uint16_t)(_nack_seq + 1)) {
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// seq不连续，丢包了 [AUTO-TRANSLATED:dcee49fe]
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// The sequence is not continuous, there is packet loss.
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break;
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}
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_nack_seq = *it;
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it = _seq.erase(it);
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}
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}
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void NackContext::clearNackStatus(uint16_t seq) {
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auto it = _nack_send_status.find(seq);
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if (it == _nack_send_status.end()) {
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return;
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}
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// 收到重传包与第一个nack包间的时间约等于rtt时间 [AUTO-TRANSLATED:f702811e]
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// The time between receiving the retransmitted packet and the first nack packet is approximately equal to the rtt time.
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auto rtt = getCurrentMillisecond() - it->second.first_stamp;
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_nack_send_status.erase(it);
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// 限定rtt在合理有效范围内 [AUTO-TRANSLATED:42fbed04]
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// Limit the rtt within a reasonable and valid range.
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GET_CONFIG(uint32_t, nack_maxms, Rtc::kNackMaxMS);
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GET_CONFIG(uint32_t, nack_maxcount, Rtc::kNackMaxCount);
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_rtt = max<int>(10, min<int>(rtt, nack_maxms / nack_maxcount));
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}
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void NackContext::recordNack(const FCI_NACK &nack) {
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auto now = getCurrentMillisecond();
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auto i = nack.getPid();
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for (auto flag : nack.getBitArray()) {
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if (flag) {
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auto &ref = _nack_send_status[i];
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ref.first_stamp = now;
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ref.update_stamp = now;
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ref.nack_count = 1;
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}
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++i;
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}
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// 记录太多了，移除一部分早期的记录 [AUTO-TRANSLATED:6f4ea62d]
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// There are too many records, remove some of the earlier records.
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GET_CONFIG(uint32_t, nack_maxsize, Rtc::kNackMaxSize);
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while (_nack_send_status.size() > nack_maxsize) {
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_nack_send_status.erase(_nack_send_status.begin());
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}
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}
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uint64_t NackContext::reSendNack() {
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set<uint16_t> nack_rtp;
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auto now = getCurrentMillisecond();
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GET_CONFIG(uint32_t, nack_maxms, Rtc::kNackMaxMS);
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GET_CONFIG(uint32_t, nack_maxcount, Rtc::kNackMaxCount);
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GET_CONFIG(float, nack_intervalratio, Rtc::kNackIntervalRatio);
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for (auto it = _nack_send_status.begin(); it != _nack_send_status.end();) {
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if (now - it->second.first_stamp > nack_maxms) {
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// 该rtp丢失太久了，不再要求重传 [AUTO-TRANSLATED:a0a1e471]
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// This rtp has been lost for too long, no longer require retransmission.
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it = _nack_send_status.erase(it);
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continue;
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}
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if (now - it->second.update_stamp < nack_intervalratio * _rtt) {
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// 距离上次nack不足2倍的rtt，不用再发送nack [AUTO-TRANSLATED:0e7edf4d]
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// The distance from the last nack is less than 2 times the rtt, no need to send nack again.
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++it;
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continue;
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}
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// 此rtp需要请求重传 [AUTO-TRANSLATED:c29d8eb5]
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// This rtp needs to request retransmission.
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nack_rtp.emplace(it->first);
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// 更新nack发送时间戳 [AUTO-TRANSLATED:16ef9fac]
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// Update the nack sending timestamp.
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it->second.update_stamp = now;
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if (++(it->second.nack_count) == nack_maxcount) {
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// nack次数太多，移除之 [AUTO-TRANSLATED:1b684a9c]
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// Too many nack times, remove it.
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it = _nack_send_status.erase(it);
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continue;
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}
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++it;
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}
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int pid = -1;
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vector<bool> vec;
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for (auto it = nack_rtp.begin(); it != nack_rtp.end();) {
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if (pid == -1) {
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pid = *it;
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vec.assign(FCI_NACK::kBitSize, false);
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++it;
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continue;
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}
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auto inc = *it - pid;
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if (inc > (ssize_t)FCI_NACK::kBitSize) {
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// 新的nack包 [AUTO-TRANSLATED:aec9b818]
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// New nack packet.
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doNack(FCI_NACK(pid, vec), false);
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pid = -1;
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continue;
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}
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// 这个包丢了 [AUTO-TRANSLATED:60f91f2f]
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// This packet is lost.
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vec[inc - 1] = true;
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++it;
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}
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if (pid != -1) {
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doNack(FCI_NACK(pid, vec), false);
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}
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// 没有任何包需要重传时返回0，否则返回下次重传间隔(不得低于5ms) [AUTO-TRANSLATED:c326264d]
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// Return 0 when there are no packets to retransmit, otherwise return the next retransmission interval (not less than 5ms).
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return _nack_send_status.empty() ? 0 : _rtt;
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}
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} // namespace mediakit
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