mirror of
https://github.com/ZLMediaKit/ZLMediaKit.git
synced 2024-10-31 00:37:39 +08:00
244 lines
6.7 KiB
C++
244 lines
6.7 KiB
C++
/*
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* Copyright (c) 2016 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 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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static constexpr uint32_t kMaxNackMS = 10 * 1000;
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void NackList::push_back(RtpPacket::Ptr 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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while (get_cache_ms() > kMaxNackMS) {
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//需要清除部分nack缓存
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pop_front();
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}
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}
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void NackList::for_each_nack(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
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RtpPacket::Ptr *ptr = get_rtp(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::pop_front() {
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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::get_rtp(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::get_cache_ms() {
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if (_nack_cache_seq.size() < 2) {
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return 0;
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}
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uint32_t back = _nack_cache_pkt[_nack_cache_seq.back()]->getStampMS();
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uint32_t front = _nack_cache_pkt[_nack_cache_seq.front()]->getStampMS();
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if (back >= front) {
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return back - front;
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}
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//很有可能回环了
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return back + (UINT32_MAX - front);
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}
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////////////////////////////////////////////////////////////////////////////////////////////////
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void NackContext::received(uint16_t seq, bool is_rtx) {
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if (!_last_max_seq && _seq.empty()) {
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_last_max_seq = seq - 1;
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}
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if (is_rtx || (seq < _last_max_seq && !(seq < 1024 && _last_max_seq > UINT16_MAX - 1024))) {
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//重传包或
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//seq回退，且非回环，那么这个应该是重传包
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onRtx(seq);
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return;
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}
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_seq.emplace(seq);
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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) {
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return;
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}
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if (diff > UINT16_MAX / 2) {
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//回环
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_seq.clear();
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_last_max_seq = min_seq;
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_nack_send_status.clear();
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return;
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}
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if (_seq.size() == diff + 1 && _last_max_seq + 1 == min_seq) {
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//都是连续的seq，未丢包
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_seq.clear();
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_last_max_seq = max_seq;
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} else {
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//seq不连续，有丢包
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if (min_seq == _last_max_seq + 1) {
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//前面部分seq是连续的，未丢包，移除之
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eraseFrontSeq();
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}
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//有丢包，丢包从_last_max_seq开始
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auto nack_rtp_count = FCI_NACK::kBitSize;
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if (max_seq - _last_max_seq > nack_rtp_count) {
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vector<bool> vec;
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vec.resize(FCI_NACK::kBitSize, false);
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for (auto i = 0; i < nack_rtp_count; ++i) {
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vec[i] = _seq.find(_last_max_seq + i + 2) == _seq.end();
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}
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doNack(FCI_NACK(_last_max_seq + 1, vec), true);
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_last_max_seq += nack_rtp_count + 1;
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if (_last_max_seq >= max_seq) {
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_seq.clear();
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} else {
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auto it = _seq.emplace_hint(_seq.begin(), _last_max_seq + 1);
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_seq.erase(_seq.begin(), it);
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}
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}
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}
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}
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void NackContext::setOnNack(onNack cb) {
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_cb = std::move(cb);
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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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if (_cb) {
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_cb(nack);
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}
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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
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for (auto it = _seq.begin(); it != _seq.end();) {
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if (*it != _last_max_seq + 1) {
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//seq不连续，丢包了
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break;
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}
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_last_max_seq = *it;
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it = _seq.erase(it);
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}
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}
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void NackContext::onRtx(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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auto rtt = getCurrentMillisecond() - it->second.update_stamp;
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_nack_send_status.erase(it);
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if (rtt >= 0) {
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//rtt不肯小于0
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_rtt = rtt;
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//InfoL << "rtt:" << rtt;
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}
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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
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while (_nack_send_status.size() > kNackMaxSize) {
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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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for (auto it = _nack_send_status.begin(); it != _nack_send_status.end();) {
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if (now - it->second.first_stamp > kNackMaxMS) {
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//该rtp丢失太久了，不再要求重传
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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 < kNackIntervalRatio * _rtt) {
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//距离上次nack不足2倍的rtt，不用再发送nack
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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
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nack_rtp.emplace(it->first);
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//更新nack发送时间戳
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it->second.update_stamp = now;
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if (++(it->second.nack_count) == kNackMaxCount) {
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//nack次数太多，移除之
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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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if (_nack_send_status.empty()) {
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//不需要再发送nack
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return 0;
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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.resize(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 > FCI_NACK::kBitSize) {
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//新的nack包
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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
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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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//重传间隔不得低于5ms
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return max(_rtt, 5);
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}
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