diff --git a/examples/server-tls/main.go b/examples/server-tls/main.go
index fdab6e8c..b7684036 100644
--- a/examples/server-tls/main.go
+++ b/examples/server-tls/main.go
@@ -28,7 +28,7 @@ func handleConn(conn *gortsplib.ServerConn) {
 	log.Printf("client connected")
 
 	// called after receiving a DESCRIBE request.
-	onDescribe := func(req *base.Request) (*base.Response, error) {
+	onDescribe := func(req *base.Request) (*base.Response, []byte, error) {
 		mutex.Lock()
 		defer mutex.Unlock()
 
@@ -36,17 +36,12 @@ func handleConn(conn *gortsplib.ServerConn) {
 		if publisher == nil {
 			return &base.Response{
 				StatusCode: base.StatusNotFound,
-			}, nil
+			}, nil, nil
 		}
 
 		return &base.Response{
 			StatusCode: base.StatusOK,
-			Header: base.Header{
-				"Content-Base": base.HeaderValue{req.URL.String() + "/"},
-				"Content-Type": base.HeaderValue{"application/sdp"},
-			},
-			Body: sdp,
-		}, nil
+		}, sdp, nil
 	}
 
 	// called after receiving an ANNOUNCE request.
diff --git a/examples/server-udp/main.go b/examples/server-udp/main.go
index fb226d0a..0b9a84d4 100644
--- a/examples/server-udp/main.go
+++ b/examples/server-udp/main.go
@@ -27,7 +27,7 @@ func handleConn(conn *gortsplib.ServerConn) {
 	log.Printf("client connected")
 
 	// called after receiving a DESCRIBE request.
-	onDescribe := func(req *base.Request) (*base.Response, error) {
+	onDescribe := func(req *base.Request) (*base.Response, []byte, error) {
 		mutex.Lock()
 		defer mutex.Unlock()
 
@@ -35,17 +35,12 @@ func handleConn(conn *gortsplib.ServerConn) {
 		if publisher == nil {
 			return &base.Response{
 				StatusCode: base.StatusNotFound,
-			}, nil
+			}, nil, nil
 		}
 
 		return &base.Response{
 			StatusCode: base.StatusOK,
-			Header: base.Header{
-				"Content-Base": base.HeaderValue{req.URL.String() + "/"},
-				"Content-Type": base.HeaderValue{"application/sdp"},
-			},
-			Body: sdp,
-		}, nil
+		}, sdp, nil
 	}
 
 	// called after receiving an ANNOUNCE request.
diff --git a/examples/server/main.go b/examples/server/main.go
index 73067cc0..982024f2 100644
--- a/examples/server/main.go
+++ b/examples/server/main.go
@@ -27,7 +27,7 @@ func handleConn(conn *gortsplib.ServerConn) {
 	log.Printf("client connected")
 
 	// called after receiving a DESCRIBE request.
-	onDescribe := func(req *base.Request) (*base.Response, error) {
+	onDescribe := func(req *base.Request) (*base.Response, []byte, error) {
 		mutex.Lock()
 		defer mutex.Unlock()
 
@@ -35,17 +35,12 @@ func handleConn(conn *gortsplib.ServerConn) {
 		if publisher == nil {
 			return &base.Response{
 				StatusCode: base.StatusNotFound,
-			}, nil
+			}, nil, nil
 		}
 
 		return &base.Response{
 			StatusCode: base.StatusOK,
-			Header: base.Header{
-				"Content-Base": base.HeaderValue{req.URL.String() + "/"},
-				"Content-Type": base.HeaderValue{"application/sdp"},
-			},
-			Body: sdp,
-		}, nil
+		}, sdp, nil
 	}
 
 	// called after receiving an ANNOUNCE request.
diff --git a/serverconn.go b/serverconn.go
index 8eef85cb..384c83cb 100644
--- a/serverconn.go
+++ b/serverconn.go
@@ -146,7 +146,8 @@ type ServerConnReadHandlers struct {
 	OnOptions func(req *base.Request) (*base.Response, error)
 
 	// called after receiving a DESCRIBE request.
-	OnDescribe func(req *base.Request) (*base.Response, error)
+	// the 2nd return value is a SDP, that is inserted into the response.
+	OnDescribe func(req *base.Request) (*base.Response, []byte, error)
 
 	// called after receiving an ANNOUNCE request.
 	OnAnnounce func(req *base.Request, tracks Tracks) (*base.Response, error)
@@ -444,7 +445,19 @@ func (sc *ServerConn) handleRequest(req *base.Request) (*base.Response, error) {
 				}, err
 			}
 
-			return sc.readHandlers.OnDescribe(req)
+			res, sdp, err := sc.readHandlers.OnDescribe(req)
+
+			if res.StatusCode == base.StatusOK && sdp != nil {
+				if res.Header == nil {
+					res.Header = make(base.Header)
+				}
+
+				res.Header["Content-Base"] = base.HeaderValue{req.URL.String() + "/"}
+				res.Header["Content-Type"] = base.HeaderValue{"application/sdp"}
+				res.Body = sdp
+			}
+
+			return res, err
 		}
 
 	case base.Announce:
@@ -516,7 +529,7 @@ func (sc *ServerConn) handleRequest(req *base.Request) (*base.Response, error) {
 
 			res, err := sc.readHandlers.OnAnnounce(req, tracks)
 
-			if res.StatusCode == 200 {
+			if res.StatusCode == base.StatusOK {
 				sc.state = ServerConnStatePreRecord
 				sc.setupPath = &reqPath
 
@@ -629,7 +642,7 @@ func (sc *ServerConn) handleRequest(req *base.Request) (*base.Response, error) {
 
 			res, err := sc.readHandlers.OnSetup(req, th, path, trackID)
 
-			if res.StatusCode == 200 {
+			if res.StatusCode == base.StatusOK {
 				sc.setupProtocol = &th.Protocol
 
 				if sc.setuppedTracks == nil {
@@ -710,7 +723,7 @@ func (sc *ServerConn) handleRequest(req *base.Request) (*base.Response, error) {
 
 			res, err := sc.readHandlers.OnPlay(req)
 
-			if res.StatusCode == 200 && sc.state != ServerConnStatePlay {
+			if res.StatusCode == base.StatusOK && sc.state != ServerConnStatePlay {
 				sc.state = ServerConnStatePlay
 				sc.frameModeEnable()
 			}
@@ -743,7 +756,7 @@ func (sc *ServerConn) handleRequest(req *base.Request) (*base.Response, error) {
 
 			res, err := sc.readHandlers.OnRecord(req)
 
-			if res.StatusCode == 200 {
+			if res.StatusCode == base.StatusOK {
 				sc.state = ServerConnStateRecord
 				sc.frameModeEnable()
 			}
@@ -767,7 +780,7 @@ func (sc *ServerConn) handleRequest(req *base.Request) (*base.Response, error) {
 
 			res, err := sc.readHandlers.OnPause(req)
 
-			if res.StatusCode == 200 {
+			if res.StatusCode == base.StatusOK {
 				switch sc.state {
 				case ServerConnStatePlay:
 					sc.frameModeDisable()
diff --git a/serverconn_test.go b/serverconn_test.go
index 050d0319..ff680b59 100644
--- a/serverconn_test.go
+++ b/serverconn_test.go
@@ -78,18 +78,18 @@ func (ts *testServ) handleConn(conn *ServerConn) {
 	defer ts.wg.Done()
 	defer conn.Close()
 
-	onDescribe := func(req *base.Request) (*base.Response, error) {
+	onDescribe := func(req *base.Request) (*base.Response, []byte, error) {
 		reqPath, ok := req.URL.RTSPPath()
 		if !ok {
 			return &base.Response{
 				StatusCode: base.StatusBadRequest,
-			}, fmt.Errorf("invalid path (%s)", req.URL)
+			}, nil, fmt.Errorf("invalid path (%s)", req.URL)
 		}
 
 		if reqPath != "teststream" {
 			return &base.Response{
 				StatusCode: base.StatusBadRequest,
-			}, fmt.Errorf("invalid path (%s)", req.URL)
+			}, nil, fmt.Errorf("invalid path (%s)", req.URL)
 		}
 
 		ts.mutex.Lock()
@@ -98,17 +98,12 @@ func (ts *testServ) handleConn(conn *ServerConn) {
 		if ts.publisher == nil {
 			return &base.Response{
 				StatusCode: base.StatusNotFound,
-			}, nil
+			}, nil, nil
 		}
 
 		return &base.Response{
 			StatusCode: base.StatusOK,
-			Header: base.Header{
-				"Content-Base": base.HeaderValue{req.URL.String() + "/"},
-				"Content-Type": base.HeaderValue{"application/sdp"},
-			},
-			Body: ts.sdp,
-		}, nil
+		}, ts.sdp, nil
 	}
 
 	onAnnounce := func(req *base.Request, tracks Tracks) (*base.Response, error) {