diff --git a/3rdpart/assert.h b/3rdpart/assert.h
index c3b4b1c2..e5699be1 100644
--- a/3rdpart/assert.h
+++ b/3rdpart/assert.h
@@ -12,19 +12,20 @@
 #define ZLMEDIAKIT_ASSERT_H
 
 #include <stdio.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+extern void Assert_Throw(int failed, const char *exp, const char *func, const char *file, int line);
+#ifdef __cplusplus
+}
+#endif
+
 #ifndef NDEBUG
     #ifdef assert
         #undef assert
     #endif//assert
 
-    #ifdef __cplusplus
-    extern "C" {
-    #endif
-    extern void Assert_Throw(int failed, const char *exp, const char *func, const char *file, int line);
-    #ifdef __cplusplus
-    }
-    #endif
-
     #define assert(exp) Assert_Throw(!(exp), #exp, __FUNCTION__, __FILE__, __LINE__);
 #else
     #define	assert(e)	((void)0)
diff --git a/webrtc/Sdp.cpp b/webrtc/Sdp.cpp
index 10074f7d..9b00fd4c 100644
--- a/webrtc/Sdp.cpp
+++ b/webrtc/Sdp.cpp
@@ -3,10 +3,14 @@
 //
 
 #include "Sdp.h"
+#include "assert.h"
+#include "Common/Parser.h"
 #include <inttypes.h>
 
+#define CHECK(exp) Assert_Throw(!(exp), #exp, __FUNCTION__, __FILE__, __LINE__);
+
 using onCreateSdpItem = function<SdpItem::Ptr(const string &key, const string &value)>;
-static unordered_map<string, onCreateSdpItem> sdpItemCreator;
+static map<string, onCreateSdpItem, StrCaseCompare> sdpItemCreator;
 
 template <typename Item>
 void registerSdpItem(){
@@ -89,17 +93,15 @@ static bool registerAllItem(){
     return true;
 }
 
-TrackType getTrackType(const string &str){
-    if (str == "video") {
-        return TrackVideo;
-    }
-    if (str == "audio") {
-        return TrackAudio;
-    }
-    if (str == "application") {
-        return TrackApplication;
-    }
-    return TrackInvalid;
+static map<string, TrackType, StrCaseCompare> track_str_map = {
+        {"video",       TrackVideo},
+        {"audio",       TrackAudio},
+        {"application", TrackApplication}
+};
+
+TrackType getTrackType(const string &str) {
+    auto it = track_str_map.find(str);
+    return it == track_str_map.end() ? TrackInvalid : it->second;
 }
 
 const char* getTrackString(TrackType type){
@@ -111,17 +113,15 @@ const char* getTrackString(TrackType type){
     }
 }
 
-DtlsRole getDtlsRole(const string &str){
-    if (str == "active") {
-        return DtlsRole::active;
-    }
-    if (str == "passive") {
-        return DtlsRole::passive;
-    }
-    if (str == "actpass") {
-        return DtlsRole::actpass;
-    }
-    return DtlsRole::invalid;
+static map<string, DtlsRole, StrCaseCompare> dtls_role_map = {
+        {"active",  DtlsRole::active},
+        {"passive", DtlsRole::passive},
+        {"actpass", DtlsRole::actpass}
+};
+
+DtlsRole getDtlsRole(const string &str) {
+    auto it = dtls_role_map.find(str);
+    return it == dtls_role_map.end() ? DtlsRole::invalid : it->second;
 }
 
 const char* getDtlsRoleString(DtlsRole role){
@@ -133,20 +133,16 @@ const char* getDtlsRoleString(DtlsRole role){
     }
 }
 
-RtpDirection getRtpDirection(const string &str){
-    if (str == "sendonly") {
-        return RtpDirection::sendonly;
-    }
-    if (str == "recvonly") {
-        return RtpDirection::recvonly;
-    }
-    if (str == "sendrecv") {
-        return RtpDirection::sendrecv;
-    }
-    if (str == "inactive") {
-        return RtpDirection::inactive;
-    }
-    return RtpDirection::invalid;
+static map<string, RtpDirection, StrCaseCompare> direction_map = {
+        {"sendonly", RtpDirection::sendonly},
+        {"recvonly", RtpDirection::recvonly},
+        {"sendrecv", RtpDirection::sendrecv},
+        {"inactive", RtpDirection::inactive}
+};
+
+RtpDirection getRtpDirection(const string &str) {
+    auto it = direction_map.find(str);
+    return it == direction_map.end() ? RtpDirection::invalid : it->second;
 }
 
 const char* getRtpDirectionString(RtpDirection val){
@@ -182,14 +178,15 @@ RtpDirection RtcSdpBase::getDirection() const{
     return RtpDirection::invalid;
 }
 
-SdpItem::Ptr RtcSdpBase::getItem(char key, const char *attr_key) const {
+SdpItem::Ptr RtcSdpBase::getItem(char key_c, const char *attr_key) const {
     for (auto item : items) {
-        if (item->getKey()[0] == key) {
+        string key(1, key_c);
+        if (strcasecmp(item->getKey(), key.data()) == 0) {
             if (!attr_key) {
                 return item;
             }
             auto attr = dynamic_pointer_cast<SdpAttr>(item);
-            if (attr && !strcmp(attr->detail->getKey() , attr_key)) {
+            if (attr && !strcasecmp(attr->detail->getKey() , attr_key)) {
                 return attr->detail;
             }
         }
@@ -884,6 +881,7 @@ void RtcSession::loadFrom(const string &str) {
     session_info = sdp.getSessionInfo();
     connection = sdp.getConnection();
     bandwidth = sdp.getBandwidth();
+    time = sdp.getSessionTime();
     msid_semantic = sdp.getItemClass<SdpAttrMsidSemantic>('a', "msid-semantic");
     for (auto &media : sdp.medias) {
         auto mline = media.getItemClass<SdpMedia>('m');
@@ -1036,7 +1034,7 @@ void RtcSession::loadFrom(const string &str) {
 
 string RtcCodecPlan::getFmtp(const char *key) const{
     for (auto &item : fmtp) {
-        if (item.first == key) {
+        if (strcasecmp(item.first.data(), key) == 0) {
             return item.second;
         }
     }
@@ -1052,34 +1050,41 @@ const RtcCodecPlan *RtcMedia::getPlan(uint8_t pt) const{
     return nullptr;
 }
 
-void RtcMedia::checkValid() const{
-    switch (direction) {
-        case RtpDirection::sendonly:
-        case RtpDirection::sendrecv: {
-            if (rtp_ssrc.empty()) {
-                throw std::invalid_argument("发送rtp但是未指定rtp ssrc");
-            }
-            break;
-        }
-        default: break;
-    }
+const RtcCodecPlan *RtcMedia::getPlan(const char *codec) const{
     for (auto &item : plan) {
-        if (item.codec == "rtx") {
-            if (rtx_ssrc.empty()) {
-                throw std::invalid_argument("指定开启rtx但是未指定rtx ssrc");
-            }
-            auto apt = atoi(item.getFmtp("apt").data());
-            if (!getPlan(apt)) {
-                throw std::invalid_argument("找不到rtx关联的plan信息");
-            }
+        if (strcasecmp(item.codec.data(), codec) == 0) {
+            return &item;
         }
     }
-    //todo 校验更多信息
+    return nullptr;
+}
+
+void RtcMedia::checkValid() const{
+    CHECK(type != TrackInvalid);
+    CHECK(!mid.empty());
+    CHECK(!proto.empty());
+    CHECK(direction != RtpDirection::invalid || type == TrackApplication);
+    CHECK(!plan.empty() || type == TrackApplication );
+    bool send_rtp = (direction == RtpDirection::sendonly || direction == RtpDirection::sendrecv);
+    CHECK(!rtp_ssrc.empty() || !send_rtp);
+    auto rtx_plan = getPlan("rtx");
+    if (rtx_plan) {
+        //开启rtx后必须指定rtx_ssrc
+        CHECK(!rtx_ssrc.empty() || !send_rtp);
+        auto apt = atoi(rtx_plan->getFmtp("apt").data());
+        //开启rtx后必须指定其关联的其他的plan
+        CHECK(getPlan(apt));
+    }
 }
 
 void RtcSession::checkValid() const{
+    CHECK(version == 0);
+    CHECK(!origin.empty());
+    CHECK(!session_name.empty());
+    CHECK(!msid_semantic.empty());
+    CHECK(!media.empty());
+    CHECK(group.mids.size() <= media.size());
     for (auto &item : media) {
         item.checkValid();
     }
-    //todo 校验更多信息
 }
\ No newline at end of file
diff --git a/webrtc/Sdp.h b/webrtc/Sdp.h
index 60f8c6b8..32c92cb6 100644
--- a/webrtc/Sdp.h
+++ b/webrtc/Sdp.h
@@ -134,6 +134,10 @@ public:
     void parse(const string &str) override;
     string toString() const override;
     const char* getKey() const override { return "o";}
+    bool empty() const {
+        return username.empty() || session_id.empty() || session_version.empty()
+               || nettype.empty() || addrtype.empty() || address.empty();
+    }
 };
 
 class SdpConnection : public SdpItem {
@@ -233,6 +237,9 @@ public:
     void parse(const string &str) override;
     string toString() const override;
     const char* getKey() const override { return "msid-semantic";}
+    bool empty() const {
+        return msid.empty();
+    }
 };
 
 class SdpAttrRtcp : public SdpItem {
@@ -467,10 +474,11 @@ public:
     SdpItem::Ptr getItem(char key, const char *attr_key = nullptr) const;
 
     template<typename cls>
-    vector<cls> getAllItem(char key, const char *attr_key = nullptr) const {
+    vector<cls> getAllItem(char key_c, const char *attr_key = nullptr) const {
         vector<cls> ret;
         for (auto item : items) {
-            if (item->getKey()[0] == key) {
+            string key(1, key_c);
+            if (strcasecmp(item->getKey(), key.data()) == 0) {
                 if (!attr_key) {
                     auto c = dynamic_pointer_cast<cls>(item);
                     if (c) {
@@ -478,7 +486,7 @@ public:
                     }
                 } else {
                     auto attr = dynamic_pointer_cast<SdpAttr>(item);
-                    if (attr && !strcmp(attr->detail->getKey(), attr_key)) {
+                    if (attr && !strcasecmp(attr->detail->getKey(), attr_key)) {
                         auto c = dynamic_pointer_cast<cls>(attr->detail);
                         if (c) {
                             ret.emplace_back(*c);
@@ -518,7 +526,7 @@ public:
     string mslabel;
     string label;
 
-    bool empty() const {return ssrc == 0;}
+    bool empty() const {return ssrc == 0 && cname.empty();}
 };
 
 //rtc传输编码方案
@@ -582,6 +590,7 @@ public:
 
     void checkValid() const;
     const RtcCodecPlan *getPlan(uint8_t pt) const;
+    const RtcCodecPlan *getPlan(const char *codec) const;
 };
 
 class RtcSession{
@@ -590,6 +599,7 @@ public:
     SdpOrigin origin;
     string session_name;
     string session_info;
+    SdpTime time;
     SdpConnection connection;
     SdpBandwidth bandwidth;
     SdpAttrMsidSemantic msid_semantic;