diff --git a/webrtc/Sdp.cpp b/webrtc/Sdp.cpp
index 9e80d54a..c5b1f174 100644
--- a/webrtc/Sdp.cpp
+++ b/webrtc/Sdp.cpp
@@ -286,9 +286,9 @@ void RtcSessionSdp::parse(const string &str) {
             item->parse(value);
         }
         if (media) {
-            media->items.push_back(std::move(item));
+            media->addItem(std::move(item));
         } else {
-            items.push_back(std::move(item));
+            addItem(std::move(item));
         }
     }
 }
@@ -953,7 +953,7 @@ void RtcSession::loadFrom(const string &str) {
     group = sdp.getItemClass<SdpAttrGroup>('a', "group");
 }
 
-static void toRtsp(vector <SdpItem::Ptr> &items) {
+void RtcSdpBase::toRtsp() {
     for (auto it = items.begin(); it != items.end();) {
         switch ((*it)->getKey()[0]) {
             case 'v':
@@ -1010,10 +1010,10 @@ string RtcSession::toRtspSdp() const{
 
     CHECK(!copy.media.empty());
     auto sdp = copy.toRtcSessionSdp();
-    toRtsp(sdp->items);
+    sdp->toRtsp();
     int i = 0;
     for (auto &m : sdp->medias) {
-        toRtsp(m.items);
+        m.toRtsp();
         m.addAttr(std::make_shared<SdpCommon>("control", string("trackID=") + to_string(i++)));
     }
     return sdp->toString();
diff --git a/webrtc/Sdp.h b/webrtc/Sdp.h
index d49a72aa..90746260 100644
--- a/webrtc/Sdp.h
+++ b/webrtc/Sdp.h
@@ -490,18 +490,16 @@ public:
 
 class RtcSdpBase {
 public:
-    std::vector<SdpItem::Ptr> items;
-    void addItem(SdpItem::Ptr item) { items.push_back(item); }
+    void addItem(SdpItem::Ptr item) { items.push_back(std::move(item)); }
     void addAttr(SdpItem::Ptr attr) {
         auto item = std::make_shared<SdpAttr>();
         item->detail = std::move(attr);
-        items.push_back(item);
+        items.push_back(std::move(item));
     }
-    SdpItem::Ptr findItem(char key) const { return getItem(key);}
-    SdpItem::Ptr findAttr(const char* key) const { return getItem('a', key);}
-public:
+
     virtual ~RtcSdpBase() = default;
     virtual std::string toString() const;
+    void toRtsp();
 
     RtpDirection getDirection() const;
 
@@ -548,6 +546,9 @@ public:
         }
         return ret;
     }
+
+private:
+    std::vector<SdpItem::Ptr> items;
 };
 
 class RtcSessionSdp : public RtcSdpBase{