diff --git a/webrtc/Sdp.cpp b/webrtc/Sdp.cpp
index 38875bcc..dae5d776 100644
--- a/webrtc/Sdp.cpp
+++ b/webrtc/Sdp.cpp
@@ -161,9 +161,9 @@ const char* getRtpDirectionString(RtpDirection val){
 
 //////////////////////////////////////////////////////////////////////////////////////////
 
-void RtcSdp::parse(const string &str) {
+void RtcSessionSdp::parse(const string &str) {
     static auto flag = registerAllItem();
-    RtcMedia *media = nullptr;
+    RtcMediaSdp *media = nullptr;
     auto lines = split(str, "\n");
     for(auto &line : lines){
         trim(line);
@@ -173,7 +173,7 @@ void RtcSdp::parse(const string &str) {
         auto key = line.substr(0, 1);
         auto value = line.substr(2);
         if (key == "m") {
-            medias.emplace_back(RtcMedia());
+            medias.emplace_back(RtcMediaSdp());
             media = &medias.back();
         }
 
@@ -193,7 +193,7 @@ void RtcSdp::parse(const string &str) {
     }
 }
 
-string RtcSdp::toString() const {
+string RtcSessionSdp::toString() const {
     _StrPrinter printer;
     for (auto &item : items) {
         printer << item->getKey() << "=" << item->toString() << "\r\n";
@@ -207,7 +207,7 @@ string RtcSdp::toString() const {
 
 //////////////////////////////////////////////////////////////////////
 
-string RtcMedia::toString() const {
+string RtcMediaSdp::toString() const {
     _StrPrinter printer;
     for (auto &item : items) {
         printer << item->getKey() << "=" << item->toString() << "\r\n";
@@ -215,7 +215,7 @@ string RtcMedia::toString() const {
     return std::move(printer);
 }
 
-RtpDirection RtcMedia::getDirection() const{
+RtpDirection RtcMediaSdp::getDirection() const{
     for (auto &item : items) {
         auto attr = dynamic_pointer_cast<SdpAttr>(item);
         if (attr) {
@@ -790,10 +790,10 @@ void test_sdp(){
                   "a=sctpmap:5000 webrtc-datachannel 1024\n"
                   "a=sctp-port:5000";
 
-    RtcSdp sdp1;
+    RtcSessionSdp sdp1;
     sdp1.parse(str1);
 
-    RtcSdp sdp2;
+    RtcSessionSdp sdp2;
     sdp2.parse(str2);
 
     for (auto media : sdp1.medias) {
diff --git a/webrtc/Sdp.h b/webrtc/Sdp.h
index 9c0d2740..325c11c0 100644
--- a/webrtc/Sdp.h
+++ b/webrtc/Sdp.h
@@ -421,7 +421,7 @@ public:
     const char* getKey() const override { return "candidate";}
 };
 
-class RtcMedia {
+class RtcMediaSdp {
 public:
     vector<SdpItem::Ptr> items;
     string toString() const;
@@ -430,15 +430,83 @@ public:
     RtpDirection getDirection() const;
 };
 
-class RtcSdp {
+class RtcSessionSdp {
 public:
     vector<SdpItem::Ptr> items;
-    vector<RtcMedia> medias;
+    vector<RtcMediaSdp> medias;
 
     void parse(const string &str);
     string toString() const;
 };
 
+//////////////////////////////////////////////////////////////////
+
+//ssrc类型
+enum class RtcSSRCType {
+    rtp = 0,
+    rtx,
+    sim_low,
+    sim_mid,
+    ssrc_high
+};
+
+//ssrc相关信息
+class RtcSSRC{
+public:
+    RtcSSRCType type;
+    string cname;
+    string msid;
+    string mslabel;
+    string label;
+};
+
+//rtc传输编码方案
+class RtcPlan{
+public:
+    uint8_t pt;
+    string codec;
+    uint32_t sample_rate;
+    //音频时有效
+    uint32_t channel = 0;
+    vector<std::pair<string/*key*/, string/*value*/> > fmtp;
+    vector<string> rtcp_fb;
+};
+
+//rtc 媒体描述
+class RtcCodec{
+public:
+    TrackType type;
+    string mid;
+    uint16_t port;
+    string proto;
+
+    //////// rtp ////////
+    vector<RtcPlan> plan;
+    SdpConnection rtp_addr;
+    RtpDirection direction;
+    RtcSSRC ssrc;
+
+    //////// rtx - rtcp  ////////
+    bool rtcp_mux;
+    bool rtcp_rsize;
+    uint32_t rtx_ssrc;
+    SdpAttrRtcp rtcp_addr;
+
+    //////// ice ////////
+    bool ice_trickle;
+    bool ice_lite;
+    bool ice_renomination;
+    string ice_ufrag;
+    string ice_pwd;
+    std::vector<SdpAttrCandidate> candidate;
+
+    //////// dtls ////////
+    DtlsRole role;
+    SdpAttrFingerprint fingerprint;
+
+    //////// extmap ////////
+    vector<SdpAttrExtmap> extmap;
+};