diff --git a/webrtc/Sdp.cpp b/webrtc/Sdp.cpp
index 484a9980..294c84a6 100644
--- a/webrtc/Sdp.cpp
+++ b/webrtc/Sdp.cpp
@@ -3,3 +3,231 @@
 //
 
 #include "Sdp.h"
+
+using onCreateSdpItem = function<SdpItem::Ptr(const string &key, const string &value)>;
+static unordered_map<string, onCreateSdpItem> sdpItemCreator;
+
+template <typename Item>
+void registerSdpItem(){
+    onCreateSdpItem func = [](const string &key, const string &value) {
+        auto ret = std::make_shared<Item>();
+        ret->parse(value);
+        return ret;
+    };
+    Item item;
+    InfoL << "register sdp item:" << item.getKey();
+    sdpItemCreator.emplace(item.getKey(), std::move(func));
+}
+
+static bool registerAllItem(){
+    registerSdpItem<SdpString<'v'> >();
+    registerSdpItem<SdpString<'s'> >();
+    registerSdpItem<SdpString<'i'> >();
+    registerSdpItem<SdpString<'u'> >();
+    registerSdpItem<SdpString<'e'> >();
+    registerSdpItem<SdpString<'p'> >();
+    registerSdpItem<SdpString<'z'> >();
+    registerSdpItem<SdpString<'k'> >();
+    registerSdpItem<SdpString<'r'> >();
+    registerSdpItem<SdpTime>();
+    registerSdpItem<SdpOrigin>();
+    registerSdpItem<SdpConnection>();
+    registerSdpItem<SdpBandwidth>();
+    registerSdpItem<SdpMedia>();
+    registerSdpItem<SdpAttr>();
+    registerSdpItem<SdpAttrGroup>();
+    registerSdpItem<SdpAttrMsidSemantic>();
+    registerSdpItem<SdpAttrRtcp>();
+    registerSdpItem<SdpAttrIceUfrag>();
+    registerSdpItem<SdpAttrIcePwd>();
+    registerSdpItem<SdpAttrFingerprint>();
+    registerSdpItem<SdpAttrSetup>();
+    registerSdpItem<SdpAttrMid>();
+    registerSdpItem<SdpAttrExtmap>();
+    registerSdpItem<SdpAttrRtpMap>();
+    registerSdpItem<SdpAttrRtcpFb>();
+    registerSdpItem<SdpAttrFmtp>();
+    registerSdpItem<SdpAttrSSRC>();
+    registerSdpItem<SdpAttrSctpMap>();
+    return true;
+}
+
+void RtcSdp::parse(const string &str) {
+    static auto flag = registerAllItem();
+    RtcMedia *media = nullptr;
+    auto lines = split(str, "\n");
+    for(auto &line : lines){
+        trim(line);
+        if(line.size() < 3 || line[1] != '='){
+            continue;
+        }
+        auto key = line.substr(0, 1);
+        auto value = line.substr(2);
+        if (key == "m") {
+            medias.emplace_back(RtcMedia());
+            media = &medias.back();
+        }
+
+        SdpItem::Ptr item;
+        auto it = sdpItemCreator.find(key);
+        if (it != sdpItemCreator.end()) {
+            item = it->second(key, value);
+        } else {
+            item = std::make_shared<SdpCommon>(key);
+            item->parse(value);
+        }
+        if (media) {
+            media->items.push_back(std::move(item));
+        } else {
+            items.push_back(std::move(item));
+        }
+    }
+}
+
+string RtcSdp::toString() const {
+    return std::string();
+}
+
+void SdpAttr::parse(const string &str) {
+    SdpItem::parse(str);
+    auto pos = str.find(':');
+    auto key = pos == string::npos ? str : str.substr(0, pos);
+    auto value = pos == string::npos ? string() : str.substr(pos + 1);
+    auto it = sdpItemCreator.find(key);
+    if (it != sdpItemCreator.end()) {
+        detail = it->second(key, value);
+    } else {
+        detail = std::make_shared<SdpCommon>(key);
+        detail->parse(value);
+    }
+}
+
+void test_sdp(){
+    char str1[] = "v=0\n"
+                 "o=- 380154348540553537 2 IN IP4 127.0.0.1\n"
+                 "s=-\n"
+                 "t=0 0\n"
+                 "a=group:BUNDLE video\n"
+                 "a=msid-semantic: WMS\n"
+                 "m=video 9 RTP/SAVPF 96\n"
+                 "c=IN IP4 0.0.0.0\n"
+                 "a=rtcp:9 IN IP4 0.0.0.0\n"
+                 "a=ice-ufrag:1ZFN\n"
+                 "a=ice-pwd:70P3H0jPlGz1fiJl5XZfXMZH\n"
+                 "a=ice-options:trickle\n"
+                 "a=fingerprint:sha-256 3E:10:35:6B:9A:9E:B0:55:AC:2A:88:F5:74:C1:70:32:B5:8D:88:1D:37:B0:9C:69:A6:DD:07:10:73:27:1A:16\n"
+                 "a=setup:active\n"
+                 "a=mid:video\n"
+                 "a=recvonly\n"
+                 "a=rtcp-mux\n"
+                 "a=rtpmap:96 H264/90000\n"
+                 "a=fmtp:96 level-asymmetry-allowed=1;packetization-mode=0;profile-level-id=42e01f";
+    char str2[] = "v=0\n"
+                  "o=- 2584450093346841581 2 IN IP4 127.0.0.1\n"
+                  "s=-\n"
+                  "t=0 0\n"
+                  "a=group:BUNDLE audio video data\n"
+                  "a=msid-semantic: WMS 616cfbb1-33a3-4d8c-8275-a199d6005549\n"
+                  "m=audio 9 UDP/TLS/RTP/SAVPF 111 103 104 9 0 8 106 105 13 110 112 113 126\n"
+                  "c=IN IP4 0.0.0.0\n"
+                  "a=rtcp:9 IN IP4 0.0.0.0\n"
+                  "a=ice-ufrag:sXJ3\n"
+                  "a=ice-pwd:yEclOTrLg1gEubBFefOqtmyV\n"
+                  "a=fingerprint:sha-256 22:14:B5:AF:66:12:C7:C7:8D:EF:4B:DE:40:25:ED:5D:8F:17:54:DD:88:33:C0:13:2E:FD:1A:FA:7E:7A:1B:79\n"
+                  "a=setup:actpass\n"
+                  "a=mid:audio\n"
+                  "a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level\n"
+                  "a=sendrecv\n"
+                  "a=rtcp-mux\n"
+                  "a=rtpmap:111 opus/48000/2\n"
+                  "a=rtcp-fb:111 transport-cc\n"
+                  "a=fmtp:111 minptime=10;useinbandfec=1\n"
+                  "a=rtpmap:103 ISAC/16000\n"
+                  "a=rtpmap:104 ISAC/32000\n"
+                  "a=rtpmap:9 G722/8000\n"
+                  "a=rtpmap:0 PCMU/8000\n"
+                  "a=rtpmap:8 PCMA/8000\n"
+                  "a=rtpmap:106 CN/32000\n"
+                  "a=rtpmap:105 CN/16000\n"
+                  "a=rtpmap:13 CN/8000\n"
+                  "a=rtpmap:110 telephone-event/48000\n"
+                  "a=rtpmap:112 telephone-event/32000\n"
+                  "a=rtpmap:113 telephone-event/16000\n"
+                  "a=rtpmap:126 telephone-event/8000\n"
+                  "a=ssrc:120276603 cname:iSkJ2vn5cYYubTve\n"
+                  "a=ssrc:120276603 msid:616cfbb1-33a3-4d8c-8275-a199d6005549 1da3d329-7399-4fe9-b20f-69606bebd363\n"
+                  "a=ssrc:120276603 mslabel:616cfbb1-33a3-4d8c-8275-a199d6005549\n"
+                  "a=ssrc:120276603 label:1da3d329-7399-4fe9-b20f-69606bebd363\n"
+                  "m=video 9 UDP/TLS/RTP/SAVPF 96 98 100 102 127 97 99 101 125\n"
+                  "c=IN IP4 0.0.0.0\n"
+                  "a=rtcp:9 IN IP4 0.0.0.0\n"
+                  "a=ice-ufrag:sXJ3\n"
+                  "a=ice-pwd:yEclOTrLg1gEubBFefOqtmyV\n"
+                  "a=fingerprint:sha-256 22:14:B5:AF:66:12:C7:C7:8D:EF:4B:DE:40:25:ED:5D:8F:17:54:DD:88:33:C0:13:2E:FD:1A:FA:7E:7A:1B:79\n"
+                  "a=setup:actpass\n"
+                  "a=mid:video\n"
+                  "a=extmap:2 urn:ietf:params:rtp-hdrext:toffset\n"
+                  "a=extmap:3 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time\n"
+                  "a=extmap:4 urn:3gpp:video-orientation\n"
+                  "a=extmap:5 http://www.ietf.org/id/draft-holmer-rmcat-transport-wide-cc-extensions-01\n"
+                  "a=extmap:6 http://www.webrtc.org/experiments/rtp-hdrext/playout-delay\n"
+                  "a=sendrecv\n"
+                  "a=rtcp-mux\n"
+                  "a=rtcp-rsize\n"
+                  "a=rtpmap:96 VP8/90000\n"
+                  "a=rtcp-fb:96 ccm fir\n"
+                  "a=rtcp-fb:96 nack\n"
+                  "a=rtcp-fb:96 nack pli\n"
+                  "a=rtcp-fb:96 goog-remb\n"
+                  "a=rtcp-fb:96 transport-cc\n"
+                  "a=rtpmap:98 VP9/90000\n"
+                  "a=rtcp-fb:98 ccm fir\n"
+                  "a=rtcp-fb:98 nack\n"
+                  "a=rtcp-fb:98 nack pli\n"
+                  "a=rtcp-fb:98 goog-remb\n"
+                  "a=rtcp-fb:98 transport-cc\n"
+                  "a=rtpmap:100 H264/90000\n"
+                  "a=rtcp-fb:100 ccm fir\n"
+                  "a=rtcp-fb:100 nack\n"
+                  "a=rtcp-fb:100 nack pli\n"
+                  "a=rtcp-fb:100 goog-remb\n"
+                  "a=rtcp-fb:100 transport-cc\n"
+                  "a=fmtp:100 level-asymmetry-allowed=1;packetization-mode=1;profile-level-id=42e01f\n"
+                  "a=rtpmap:102 red/90000\n"
+                  "a=rtpmap:127 ulpfec/90000\n"
+                  "a=rtpmap:97 rtx/90000\n"
+                  "a=fmtp:97 apt=96\n"
+                  "a=rtpmap:99 rtx/90000\n"
+                  "a=fmtp:99 apt=98\n"
+                  "a=rtpmap:101 rtx/90000\n"
+                  "a=fmtp:101 apt=100\n"
+                  "a=rtpmap:125 rtx/90000\n"
+                  "a=fmtp:125 apt=102\n"
+                  "a=ssrc-group:FID 2580761338 611523443\n"
+                  "a=ssrc:2580761338 cname:iSkJ2vn5cYYubTve\n"
+                  "a=ssrc:2580761338 msid:616cfbb1-33a3-4d8c-8275-a199d6005549 bf270496-a23e-47b5-b901-ef23096cd961\n"
+                  "a=ssrc:2580761338 mslabel:616cfbb1-33a3-4d8c-8275-a199d6005549\n"
+                  "a=ssrc:2580761338 label:bf270496-a23e-47b5-b901-ef23096cd961\n"
+                  "a=ssrc:611523443 cname:iSkJ2vn5cYYubTve\n"
+                  "a=ssrc:611523443 msid:616cfbb1-33a3-4d8c-8275-a199d6005549 bf270496-a23e-47b5-b901-ef23096cd961\n"
+                  "a=ssrc:611523443 mslabel:616cfbb1-33a3-4d8c-8275-a199d6005549\n"
+                  "a=ssrc:611523443 label:bf270496-a23e-47b5-b901-ef23096cd961\n"
+                  "a=candidate:1 1 udp %u %s %u typ host\n"
+                  "m=application 9 DTLS/SCTP 5000\n"
+                  "c=IN IP4 0.0.0.0\n"
+                  "a=ice-ufrag:sXJ3\n"
+                  "a=ice-pwd:yEclOTrLg1gEubBFefOqtmyV\n"
+                  "a=fingerprint:sha-256 22:14:B5:AF:66:12:C7:C7:8D:EF:4B:DE:40:25:ED:5D:8F:17:54:DD:88:33:C0:13:2E:FD:1A:FA:7E:7A:1B:79\n"
+                  "a=setup:actpass\n"
+                  "a=mid:data\n"
+                  "a=sctpmap:5000 webrtc-datachannel 1024";
+
+    RtcSdp sdp1;
+    sdp1.parse(str1);
+
+    RtcSdp sdp2;
+    sdp2.parse(str2);
+
+    InfoL << sdp1.toString();
+    InfoL << sdp2.toString();
+}
diff --git a/webrtc/Sdp.h b/webrtc/Sdp.h
index dfe47c54..aafdae04 100644
--- a/webrtc/Sdp.h
+++ b/webrtc/Sdp.h
@@ -103,6 +103,7 @@ using namespace mediakit;
 //a=ssrc:611523443 msid:616cfbb1-33a3-4d8c-8275-a199d6005549 bf270496-a23e-47b5-b901-ef23096cd961
 //a=ssrc:611523443 mslabel:616cfbb1-33a3-4d8c-8275-a199d6005549
 //a=ssrc:611523443 label:bf270496-a23e-47b5-b901-ef23096cd961
+//a=candidate:1 1 udp %u %s %u typ host
 //m=application 9 DTLS/SCTP 5000
 //c=IN IP4 0.0.0.0
 //a=ice-ufrag:sXJ3
@@ -172,21 +173,40 @@ enum class SdpType {
 
 class SdpItem {
 public:
-    SdpItem() = default;
+    using Ptr = std::shared_ptr<SdpItem>;
+    string value;
     virtual ~SdpItem() = default;
-    virtual void parse(const string &str) = 0;
-    virtual string toString() const = 0;
+    virtual void parse(const string &str) {
+        value  = str;
+    }
+    virtual string toString() const {
+        return value;
+    }
     virtual const char* getKey() = 0;
 };
 
+template <char KEY>
+class SdpString : public SdpItem{
+public:
+    // *=*
+    const char* getKey() override { static string key(1, KEY); return key.data();}
+};
+
+class SdpCommon : public SdpItem {
+public:
+    string key;
+    SdpCommon(string key) { this->key = std::move(key); }
+    const char* getKey() override { return key.data();}
+};
+
 class SdpTime : public SdpItem{
 public:
     //5.9.  Timing ("t=")
     // t=<start-time> <stop-time>
     uint64_t start;
     uint64_t stop;
-    void parse(const string &str) override;
-    string toString() const override;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
     const char* getKey() override { return "t";}
 };
 
@@ -201,8 +221,8 @@ public:
     string nettype;
     string addrtype;
     string address;
-    void parse(const string &str) override;
-    string toString() const override;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
     const char* getKey() override { return "o";}
 };
 
@@ -214,8 +234,8 @@ public:
     string nettype;
     string addrtype;
     string address;
-    void parse(const string &str) override;
-    string toString() const override;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
     const char* getKey() override { return "c";}
 };
 
@@ -228,8 +248,8 @@ public:
     string bwtype;
     int bandwidth;
 
-    void parse(const string &str) override;
-    string toString() const override;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
     const char* getKey() override { return "b";}
 };
 
@@ -242,20 +262,20 @@ public:
     vector<string> proto;
     vector<uint8_t> fmt;
 
-    void parse(const string &str) override;
-    string toString() const override;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
     const char* getKey() override { return "m";}
 };
 
 class SdpAttr : public SdpItem{
 public:
+    using Ptr = std::shared_ptr<SdpAttr>;
     //5.13.  Attributes ("a=")
     //a=<attribute>
     //a=<attribute>:<value>
-    string name;
-    string value;
+    SdpItem::Ptr detail;
     void parse(const string &str) override;
-    string toString() const override;
+    string toString() const override { return SdpItem::toString(); };
     const char* getKey() override { return "a";}
 };
 
@@ -267,26 +287,168 @@ public:
     //  identifiers that are part of the same lip sync group.
     string type;
     vector<string> mid;
-    void parse(const string &str) override;
-    string toString() const override;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
     const char* getKey() override { return "group";}
 };
 
+class SdpAttrMsidSemantic : public SdpItem {
+public:
+    string name{"WMS"};
+    string mid;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "msid-semantic";}
+};
+
+class SdpAttrRtcp : public SdpItem {
+public:
+    // c=IN IP4 224.2.17.12/127
+    // c=<nettype> <addrtype> <connection-address>
+    uint16_t port;
+    string nettype;
+    string addrtype;
+    string address;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "rtcp";}
+};
+
+class SdpAttrIceUfrag : public SdpItem {
+public:
+    //a=ice-ufrag:sXJ3
+    string value;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "ice-ufrag";}
+};
+
+class SdpAttrIcePwd : public SdpItem {
+public:
+    //a=ice-pwd:yEclOTrLg1gEubBFefOqtmyV
+    string value;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "ice-pwd";}
+};
+
+class SdpAttrFingerprint : public SdpItem {
+public:
+    //a=fingerprint:sha-256 22:14:B5:AF:66:12:C7:C7:8D:EF:4B:DE:40:25:ED:5D:8F:17:54:DD:88:33:C0:13:2E:FD:1A:FA:7E:7A:1B:79
+    string algorithm;
+    string value;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "fingerprint";}
+};
+
+class SdpAttrSetup : public SdpItem {
+public:
+    //a=setup:actpass
+    DtlsRole role{DtlsRole::invalid};
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "setup";}
+};
+
+class SdpAttrMid : public SdpItem {
+public:
+    //a=mid:audio
+    string mid;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "mid";}
+};
+
+class SdpAttrExtmap : public SdpItem {
+public:
+    //a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
+    int index;
+    string value;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "extmap";}
+};
+
+class SdpAttrRtpMap : public SdpItem {
+public:
+    //a=rtpmap:111 opus/48000/2
+    uint8_t pt;
+    string codec;
+    int sample_rate;
+    int channel;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "rtpmap";}
+};
+
+class SdpAttrRtcpFb : public SdpItem {
+public:
+    //a=rtcp-fb:111 transport-cc
+    uint8_t pt;
+    string value;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "rtcp-fb";}
+};
+
+class SdpAttrFmtp : public SdpItem {
+public:
+    //a=rtcp-fb:111 transport-cc
+    uint8_t pt;
+    map<string, string> values;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "fmtp";}
+};
+
+class SdpAttrSSRC : public SdpItem {
+public:
+    //a=ssrc:120276603 cname:iSkJ2vn5cYYubTve
+    uint32_t ssrc;
+    string key;
+    string value;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "ssrc";}
+};
+
+class SdpAttrSctpMap : public SdpItem {
+public:
+    //a=ssrc:120276603 cname:iSkJ2vn5cYYubTve
+    uint16_t port;
+    string name;
+    int mtu;
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "sctpmap";}
+};
+
+class SdpAttrCandidate : public SdpItem {
+public:
+    //a=candidate:%s 1 udp %u %s %u typ %s
+    void parse(const string &str) override {SdpItem::parse(str); };
+    string toString() const override { return SdpItem::toString(); };
+    const char* getKey() override { return "candidate";}
+};
+
+
 class RtcMedia {
 public:
-    //m=<media> <port> <proto> <fmt> ...
-    SdpMedia media;
-    //c=<nettype> <addrtype> <connection-address>
-    SdpConnection connection;
-    //a=<attribute>:<value>
-    vector<SdpAttr> attributes;
-
+    vector<SdpItem::Ptr> items;
     bool haveAttr(const char *attr) const;
     string getAttrValue(const char *attr) const;
 };
 
 class RtcSdp {
 public:
+    vector<SdpItem::Ptr> items;
+    vector<RtcMedia> medias;
+
+    void parse(const string &str);
+    string toString() const;
+
+#if 0
     /////Session description（会话级别描述）////
     //v=  (protocol version)
     int version;
@@ -319,8 +481,7 @@ public:
     //r=* (zero or more repeat times)
     //r=<repeat interval> <active duration> <offsets from start-time>
     string repeat;
-    //a=* (zero or more media attribute lines)
-    vector<SdpAttr> attributes;
+#endif
 };