diff --git a/webrtc/Sdp.cpp b/webrtc/Sdp.cpp
index d4a1d8f3..4db1f14c 100644
--- a/webrtc/Sdp.cpp
+++ b/webrtc/Sdp.cpp
@@ -190,7 +190,7 @@ SdpItem::Ptr RtcSdpBase::getItem(char key, const char *attr_key) const {
             }
             auto attr = dynamic_pointer_cast<SdpAttr>(item);
             if (attr && attr->detail->getKey() == attr_key) {
-                return item;
+                return attr->detail;
             }
         }
     }
@@ -869,3 +869,32 @@ void test_sdp(){
     InfoL << sdp1.toString();
     InfoL << sdp2.toString();
 }
+
+void RtcSession::loadFrom(const string &str) {
+    RtcSessionSdp sdp;
+    sdp.parse(str);
+
+    version = sdp.getVersion();
+    origin = sdp.getOrigin();
+    session_name = sdp.getSessionName();
+    session_info = sdp.getSessionInfo();
+    connection = sdp.getConnection();
+    bandwidth = sdp.getBandwidth();
+    auto group = sdp.getItemClass<SdpAttrGroup>('a', "group");
+    auto mids = group.mids;
+
+    for (auto &media : sdp.medias) {
+        auto mline = media.getItemClass<SdpMedia>('m');
+        switch (mline.type) {
+            case TrackVideo:
+            case TrackAudio:
+            case TrackApplication:
+                break;
+            default: throw std::invalid_argument(StrPrinter << "不识别的media类型:" << mline.toString());
+        }
+        RtcMedia rtc_media;
+        rtc_media.type = mline.type;
+        rtc_media.mid = media.getStringItem('a', "mid");
+    }
+
+}
diff --git a/webrtc/Sdp.h b/webrtc/Sdp.h
index 381f51c3..ec38fb05 100644
--- a/webrtc/Sdp.h
+++ b/webrtc/Sdp.h
@@ -444,9 +444,6 @@ public:
     string getRepeatTimes() const;
     RtpDirection getDirection() const;
 
-private:
-    SdpItem::Ptr getItem(char key, const char *attr_key = nullptr) const;
-
     template<typename cls>
     cls getItemClass(char key, const char *attr_key = nullptr) const{
         auto item = dynamic_pointer_cast<cls>(getItem(key, attr_key));
@@ -463,6 +460,9 @@ private:
         }
         return item->toString();
     }
+
+private:
+    SdpItem::Ptr getItem(char key, const char *attr_key = nullptr) const;
 };
 
 class RtcSessionSdp : public RtcSdpBase{
@@ -551,6 +551,8 @@ public:
     SdpBandwidth bandwidth;
     set<TrackType> group_bundle;
     vector<RtcMedia> media;
+
+    void loadFrom(const string &sdp);
 };