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优化rtp排序抖动缓存算法，提高webrtc/rtsp抗丢包性能

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This commit is contained in:
xiongziliang 2023-03-05 23:24:55 +08:00
parent 4942a0f574
commit 9fdb3de8b2
3 changed files with 59 additions and 76 deletions
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2
src/Rtsp/RtpReceiver.cpp
View File

@ -14,7 +14,7 @@
namespace mediakit {
RtpTrack::RtpTrack() {
setOnSort([this](uint16_t seq, RtpPacket::Ptr &packet) {
setOnSort([this](uint16_t seq, RtpPacket::Ptr packet) {
onRtpSorted(std::move(packet));
});
}

129
src/Rtsp/RtpReceiver.h
View File

@ -24,10 +24,11 @@ namespace mediakit {
template<typename T, typename SEQ = uint16_t, size_t kMax = 1024, size_t kMin = 32>
class PacketSortor {
public:
static constexpr SEQ SEQ_MAX = (std::numeric_limits<SEQ>::max)();
PacketSortor() = default;
~PacketSortor() = default;
void setOnSort(std::function<void(SEQ seq, T &packet)> cb) {
void setOnSort(std::function<void(SEQ seq, T packet)> cb) {
_cb = std::move(cb);
}
@ -35,10 +36,10 @@ public:
* 清空状态
*/
void clear() {
_started = false;
_seq_cycle_count = 0;
_pkt_sort_cache_map.clear();
_next_seq_out = 0;
_max_sort_size = kMin;
_pkt_sort_cache_map.clear();
}
/**
@ -61,24 +62,52 @@ public:
* @param packet 包负载
*/
void sortPacket(SEQ seq, T packet) {
if(!_is_inited && _next_seq_out == 0){
_next_seq_out = seq;
_is_inited = true;
if (!_started) {
// 记录第一个seq
_started = true;
_last_seq_out = seq - 1;
}
if (seq < _next_seq_out) {
if (_next_seq_out < seq + kMax) {
//过滤seq回退包(回环包除外)
return;
}
} else if (_next_seq_out && seq - _next_seq_out > ((std::numeric_limits<SEQ>::max)() >> 1)) {
//过滤seq跳变非常大的包(防止回环时乱序时收到非常大的seq)
if (seq == static_cast<SEQ>(_last_seq_out + 1)) {
// 收到下一个seq
output(seq, std::move(packet));
return;
}
//放入排序缓存
if (seq < _last_seq_out && _last_seq_out != SEQ_MAX && seq < kMax && _last_seq_out > SEQ_MAX - kMax) {
// seq回环,清空回环前缓存
flush();
_last_seq_out = SEQ_MAX;
_pkt_sort_cache_map.emplace(seq, std::move(packet));
//尝试输出排序后的包
tryPopPacket();
++_seq_cycle_count;
return;
}
if (seq <= _last_seq_out && _last_seq_out != SEQ_MAX) {
// 这个回退包已经不再等待
setBufferSize(seq);
return;
}
_pkt_sort_cache_map.emplace(seq, std::move(packet));
auto max_seq = _pkt_sort_cache_map.rbegin()->first;
auto min_seq = _pkt_sort_cache_map.begin()->first;
auto diff = max_seq - min_seq;
if (diff > (SEQ_MAX >> 1)) {
// 回环后，收到回环前的大值seq, 忽略掉
_pkt_sort_cache_map.erase(max_seq);
return;
}
if (min_seq == static_cast<SEQ>(_last_seq_out + 1) && _pkt_sort_cache_map.size() == (size_t)diff + 1) {
// 都是连续的seq, 未丢包
flush();
} else {
// seq不连续，有丢包
if (_pkt_sort_cache_map.size() >= _max_sort_size) {
//buffer太长，强行减小
popIterator(_pkt_sort_cache_map.begin());
}
}
}
void flush(){
@ -89,74 +118,28 @@ public:
}
private:
void popPacket() {
auto it = _pkt_sort_cache_map.begin();
if (it->first >= _next_seq_out) {
//过滤回跳包
popIterator(it);
return;
}
if (_next_seq_out - it->first > (0xFFFF >> 1)) {
//产生回环了
if (_pkt_sort_cache_map.size() < 2 * kMin) {
//等足够多的数据后才处理回环, 因为后面还可能出现大的SEQ
return;
}
++_seq_cycle_count;
//找到大的SEQ并清空掉，然后从小的SEQ重新开始排序
auto hit = _pkt_sort_cache_map.upper_bound((SEQ) (_next_seq_out - _pkt_sort_cache_map.size()));
while (hit != _pkt_sort_cache_map.end()) {
//回环前，清空剩余的大的SEQ的数据
_cb(hit->first, hit->second);
hit = _pkt_sort_cache_map.erase(hit);
}
//下一个回环的数据
popIterator(_pkt_sort_cache_map.begin());
return;
}
//删除回跳的数据包
_pkt_sort_cache_map.erase(it);
}
void popIterator(typename std::map<SEQ, T>::iterator it) {
auto seq = it->first;
auto data = std::move(it->second);
_pkt_sort_cache_map.erase(it);
_next_seq_out = seq + 1;
_cb(seq, data);
output(seq, std::move(data));
}
void tryPopPacket() {
int count = 0;
while ((!_pkt_sort_cache_map.empty() && _pkt_sort_cache_map.begin()->first == _next_seq_out)) {
//找到下个包，直接输出
popPacket();
++count;
void output(SEQ seq, T packet) {
_last_seq_out = seq;
_cb(seq, std::move(packet));
}
if (count) {
setSortSize();
} else if (_pkt_sort_cache_map.size() > _max_sort_size) {
//排序缓存溢出，不再继续排序
popPacket();
setSortSize();
}
}
void setSortSize() {
_max_sort_size = kMin + _pkt_sort_cache_map.size();
if (_max_sort_size > kMax) {
_max_sort_size = kMax;
}
void setBufferSize(SEQ seq) {
auto next_seq = static_cast<SEQ>(_last_seq_out + 1);
auto min_seq = _pkt_sort_cache_map.empty() ? next_seq : _pkt_sort_cache_map.begin()->first;
_max_sort_size = MAX(std::min<SEQ>(_pkt_sort_cache_map.size() + min_seq - seq, kMax), kMin);
}
private:
//第一个包是已经进入
bool _is_inited = false;
bool _started = false;
//下次应该输出的SEQ
SEQ _next_seq_out = 0;
SEQ _last_seq_out = 0;
//seq回环次数计数
size_t _seq_cycle_count = 0;
//排序缓存长度
@ -164,7 +147,7 @@ private:
//pkt排序缓存，根据seq排序
std::map<SEQ, T> _pkt_sort_cache_map;
//回调
std::function<void(SEQ seq, T &packet)> _cb;
std::function<void(SEQ seq, T packet)> _cb;
};
class RtpTrack : private PacketSortor<RtpPacket::Ptr> {

2
tests/test_sortor.cpp
View File

@ -102,7 +102,7 @@ void test_real() {
PacketSortor<uint16_t, uint16_t> sortor;
list<uint16_t> sorted_list;
sortor.setOnSort([&](uint16_t seq, const uint16_t &packet) {
sortor.setOnSort([&](uint16_t seq, uint16_t packet) {
sorted_list.push_back(seq);
});