diff --git a/auth.go b/auth.go
index a7cb0128..1439a0f8 100644
--- a/auth.go
+++ b/auth.go
@@ -20,7 +20,10 @@ func md5Hex(in string) string {
 type AuthMethod int
 
 const (
+	// basic authentication method
 	Basic AuthMethod = iota
+
+	// digest authentication method
 	Digest
 )
 
diff --git a/conn-client.go b/conn-client.go
index f05fb4ee..84815e61 100644
--- a/conn-client.go
+++ b/conn-client.go
@@ -29,7 +29,7 @@ type Track struct {
 	// track id
 	Id int
 
-	// track codec and info in SDP
+	// track codec and info in SDP format
 	Media *sdp.MediaDescription
 }
 
diff --git a/interleaved-frame.go b/interleaved-frame.go
index 45adab1c..e6094a22 100644
--- a/interleaved-frame.go
+++ b/interleaved-frame.go
@@ -11,28 +11,6 @@ const (
 	interleavedFrameMagicByte = 0x24
 )
 
-// StreamType is the type of a stream.
-type StreamType int
-
-const (
-	// StreamTypeRtp is a stream that contains RTP packets
-	StreamTypeRtp StreamType = iota
-
-	// StreamTypeRtcp is a stream that contains RTCP packets
-	StreamTypeRtcp
-)
-
-func (st StreamType) String() string {
-	switch st {
-	case StreamTypeRtp:
-		return "RTP"
-
-	case StreamTypeRtcp:
-		return "RTCP"
-	}
-	return "UNKNOWN"
-}
-
 // InterleavedFrame is an object that allows to send and receive binary data
 // within RTSP connections. It is used to send RTP and RTCP packets via TCP.
 type InterleavedFrame struct {
diff --git a/utils.go b/utils.go
index b147a402..05319069 100644
--- a/utils.go
+++ b/utils.go
@@ -11,6 +11,51 @@ const (
 	rtspMaxContentLength = 4096
 )
 
+// StreamProtocol is the protocol of a stream
+type StreamProtocol int
+
+const (
+	// invalid protocol
+	StreamProtocolInvalid StreamProtocol = iota
+
+	// UDP protocol
+	StreamProtocolUdp
+
+	// TCP protocol
+	StreamProtocolTcp
+)
+
+// String implements fmt.Stringer
+func (sp StreamProtocol) String() string {
+	if sp == StreamProtocolUdp {
+		return "udp"
+	}
+	return "tcp"
+}
+
+// StreamType is the type of a stream.
+type StreamType int
+
+const (
+	// stream that contains RTP packets
+	StreamTypeRtp StreamType = iota + 1
+
+	// stream that contains RTCP packets
+	StreamTypeRtcp
+)
+
+// String implements fmt.Stringer
+func (st StreamType) String() string {
+	switch st {
+	case StreamTypeRtp:
+		return "RTP"
+
+	case StreamTypeRtcp:
+		return "RTCP"
+	}
+	return "UNKNOWN"
+}
+
 func readBytesLimited(rb *bufio.Reader, delim byte, n int) ([]byte, error) {
 	for i := 1; i <= n; i++ {
 		byts, err := rb.Peek(i)