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整理优化webrtc ssrc与simulcast相关代码

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This commit is contained in:
ziyue 2021-10-12 21:26:01 +08:00
parent fbc5378058
commit acbe99cb43
3 changed files with 103 additions and 67 deletions
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117
webrtc/Sdp.cpp
View File

@ -870,57 +870,72 @@ void RtcSession::loadFrom(const string &str, bool check) {
}
auto ssrc_groups = media.getAllItem<SdpAttrSSRCGroup>('a', "ssrc-group");
bool have_rtx_ssrc = false;
SdpAttrSSRCGroup *ssrc_group_sim = nullptr;
SdpAttrSSRCGroup *ssrc_group_fid = nullptr;
for (auto &group : ssrc_groups) {
if (group.isFID()) {
ssrc_group_fid = &group;
have_rtx_ssrc = true;
//ssrc-group:FID字段必须包含rtp/rtx的ssrc
CHECK(group.ssrcs.size() == 2);
//根据rtp ssrc找到对象
auto it = rtc_ssrc_map.find(group.ssrcs[0]);
CHECK(it != rtc_ssrc_map.end());
//设置rtx ssrc
it->second.rtx_ssrc = group.ssrcs[1];
rtc_media.rtp_rtx_ssrc.emplace_back(it->second);
} else if (group.isSIM()) {
CHECK(!ssrc_group_sim);
ssrc_group_sim = &group;
}
}
if (ssrc_group_fid) {
//指定了ssrc-group:FID字段
for (auto ssrc : ssrc_group_fid->ssrcs) {
auto it = rtc_ssrc_map.find(ssrc);
if (it == rtc_ssrc_map.end()) {
throw std::invalid_argument("a=ssrc-group:FID字段指定的ssrc未找到");
if (!have_rtx_ssrc) {
//按照sdp顺序依次添加ssrc
for (auto &attr : ssrc_attr) {
if (attr.attribute == "cname") {
rtc_media.rtp_rtx_ssrc.emplace_back(rtc_ssrc_map[attr.ssrc]);
}
rtc_media.rtp_rtx_ssrc.emplace_back(it->second);
}
CHECK(rtc_media.rtp_rtx_ssrc.size() == 2);
} else {
}
auto simulcast = media.getItemClass<SdpAttrSimulcast>('a', "simulcast");
if (simulcast.empty()) {
//没有指定ssrc-group:FID字段,也不是simulcast，那么只有1个或0个ssrc
if (rtc_ssrc_map.size() == 1) {
rtc_media.rtp_rtx_ssrc.emplace_back(rtc_ssrc_map.begin()->second);
} else if (rtc_ssrc_map.size() > 1) {
throw std::invalid_argument("sdp中不存在a=ssrc-group:FID字段,但是ssrc却大于1个");
if (!simulcast.empty()) {
// a=rid:h send
// a=rid:m send
// a=rid:l send
// a=simulcast:send h;m;l
// 风格的simulcast
unordered_set<string> rid_map;
for (auto &rid : simulcast.rids) {
rid_map.emplace(rid);
}
for (auto &rid : media.getAllItem<SdpAttrRid>('a', "rid")) {
CHECK(rid.direction == simulcast.direction);
CHECK(rid_map.find(rid.rid) != rid_map.end());
}
} else {
//开启simulcast
rtc_media.rtp_rids = simulcast.rids;
//simulcast最少要求2种方案
CHECK(rtc_media.rtp_rids.size() >= 2);
}
CHECK(simulcast.rids.size() >= 2);
rtc_media.rtp_rids = simulcast.rids;
}
if (ssrc_group_sim) {
//指定了a=ssrc-group:SIM
for (auto ssrc : ssrc_group_sim->ssrcs) {
auto it = rtc_ssrc_map.find(ssrc);
if (it == rtc_ssrc_map.end()) {
throw std::invalid_argument("a=ssrc-group:SIM字段指定的ssrc未找到");
}
CHECK(it != rtc_ssrc_map.end());
rtc_media.rtp_ssrc_sim.emplace_back(it->second);
}
} else if (!rtc_media.rtp_rids.empty()) {
//未指定a=ssrc-group:SIM，但是指定了a=simulcast,且可能指定了ssrc
for (auto &attr : ssrc_attr) {
rtc_media.rtp_ssrc_sim.emplace_back(rtc_ssrc_map[attr.ssrc]);
//未指定a=ssrc-group:SIM, 但是指定了a=simulcast, 那么只能根据ssrc顺序来对应rid顺序
rtc_media.rtp_ssrc_sim = rtc_media.rtp_rtx_ssrc;
}
if (!rtc_media.supportSimulcast()) {
//不支持simulcast的情况下，最多一组ssrc
CHECK(rtc_media.rtp_rtx_ssrc.size() <= 1);
} else {
//simulcast的情况下，要么没有指定ssrc，要么指定的ssrc个数与rid个数一致
CHECK(rtc_media.rtp_ssrc_sim.empty() || rtc_media.rtp_ssrc_sim.size() == rtc_media.rtp_rids.size());
}
auto rtpmap_arr = media.getAllItem<SdpAttrRtpMap>('a', "rtpmap");
@ -1161,8 +1176,10 @@ RtcSessionSdp::Ptr RtcSession::toRtcSessionSdp() const{
static auto addSSRCItem = [](const RtcSSRC &rtp_ssrc, vector<SdpItem::Ptr> &items) {
CHECK(!rtp_ssrc.empty());
auto ssrc_num = rtp_ssrc.ssrc;
for (auto i = 0; i < 2; ++i) {
SdpAttrSSRC ssrc;
ssrc.ssrc = rtp_ssrc.ssrc;
ssrc.ssrc = ssrc_num;
ssrc.attribute = "cname";
ssrc.attribute_value = rtp_ssrc.cname;
@ -1185,29 +1202,38 @@ RtcSessionSdp::Ptr RtcSession::toRtcSessionSdp() const{
ssrc.attribute_value = rtp_ssrc.label;
items.emplace_back(wrapSdpAttr(std::make_shared<SdpAttrSSRC>(ssrc)));
}
if (rtp_ssrc.rtx_ssrc) {
ssrc_num = rtp_ssrc.rtx_ssrc;
} else {
break;
}
}
};
{
auto group = std::make_shared<SdpAttrSSRCGroup>();
for (auto &ssrc : m.rtp_rtx_ssrc) {
//添加a=ssrc字段
addSSRCItem(ssrc, sdp_media.items);
group->ssrcs.emplace_back(ssrc.ssrc);
}
if (group->ssrcs.size() >= 2) {
group->type = "FID";
for (auto &ssrc : m.rtp_rtx_ssrc) {
//生成a=ssrc-group:FID字段
if (ssrc.rtx_ssrc) {
//有rtx ssrc
auto group = std::make_shared<SdpAttrSSRCGroup>();
group->type = "FID";
group->ssrcs.emplace_back(ssrc.ssrc);
group->ssrcs.emplace_back(ssrc.rtx_ssrc);
sdp_media.items.emplace_back(wrapSdpAttr(std::move(group)));
}
}
}
{
if (m.rtp_ssrc_sim.size() >= 2) {
//simulcast 要求 2~3路
auto group = std::make_shared<SdpAttrSSRCGroup>();
for (auto &ssrc : m.rtp_ssrc_sim) {
//添加simulcast的ssrc
addSSRCItem(ssrc, sdp_media.items);
group->ssrcs.emplace_back(ssrc.ssrc);
}
//添加a=ssrc-group:SIM字段
@ -1294,12 +1320,22 @@ uint32_t RtcMedia::getRtpSSRC() const {
}
uint32_t RtcMedia::getRtxSSRC() const {
if (rtp_rtx_ssrc.size() > 1) {
return rtp_rtx_ssrc[1].ssrc;
if (rtp_rtx_ssrc.size()) {
return rtp_rtx_ssrc[0].rtx_ssrc;
}
return 0;
}
bool RtcMedia::supportSimulcast() const {
if (!rtp_rids.empty()) {
return true;
}
if (!rtp_ssrc_sim.empty()) {
return true;
}
return false;
}
void RtcMedia::checkValid() const{
CHECK(type != TrackInvalid);
CHECK(!mid.empty());
@ -1372,15 +1408,13 @@ bool RtcSession::supportRtcpFb(const string &name, TrackType type) const {
bool RtcSession::supportSimulcast() const {
for (auto &m : media) {
if (!m.rtp_rids.empty()) {
return true;
}
if (!m.rtp_ssrc_sim.empty()) {
if (m.supportSimulcast()) {
return true;
}
}
return false;
}
void RtcSession::checkSdp() const {
for (auto &m : media) {
if (m.type != TrackApplication && !m.rtcp_mux) {
@ -1636,6 +1670,7 @@ RETRY:
answer_media.candidate = configure.candidate;
answer_media.rtp_rids = offer_media.rtp_rids;
answer_media.rtp_ssrc_sim = offer_media.rtp_ssrc_sim;
answer_media.rtp_rtx_ssrc = offer_media.rtp_rtx_ssrc;
switch (offer_media.role) {
case DtlsRole::actpass :
case DtlsRole::active : {

2
webrtc/Sdp.h
View File

@ -573,6 +573,7 @@ public:
class RtcSSRC{
public:
uint32_t ssrc {0};
uint32_t rtx_ssrc {0};
string cname;
string msid;
string mslabel;
@ -647,6 +648,7 @@ public:
const RtcCodecPlan *getRelatedRtxPlan(uint8_t pt) const;
uint32_t getRtpSSRC() const;
uint32_t getRtxSSRC() const;
bool supportSimulcast() const;
};
class RtcSession{

5
webrtc/WebRtcTransport.cpp
View File

@ -539,9 +539,8 @@ void WebRtcTransportImp::onCheckAnswer(RtcSession &sdp) {
m.rtp_rtx_ssrc[0].msid = RTP_MSID;
if (m.getRelatedRtxPlan(m.plan[0].pt)) {
m.rtp_rtx_ssrc.emplace_back();
m.rtp_rtx_ssrc[1] = m.rtp_rtx_ssrc[0];
m.rtp_rtx_ssrc[1].ssrc += RTX_SSRC_OFFSET;
//rtx ssrc
m.rtp_rtx_ssrc[0].rtx_ssrc = m.rtp_rtx_ssrc[0].ssrc + RTX_SSRC_OFFSET;
}
}
}