diff --git a/stream/rtp/rtp.go b/stream/rtp/rtp.go
index fa62d9fb..3d474647 100644
--- a/stream/rtp/rtp.go
+++ b/stream/rtp/rtp.go
@@ -26,8 +26,10 @@ LICENSE
   along with revid in gpl.txt.  If not, see [GNU licenses](http://www.gnu.org/licenses).
 */
 
-// See https://tools.ietf.org/html/rfc6184 for rtp packet format
-
+/*
+See https://tools.ietf.org/html/rfc6184 and https://tools.ietf.org/html/rfc3550
+for rtp-h264 and rtp standards.
+*/
 package rtp
 
 const (
@@ -88,6 +90,9 @@ func (p *Pkt) Bytes() []byte {
 	buf[11] = byte(p.SSRC)
 
 	buf = append(buf, p.Payload...)
+	// see https://tools.ietf.org/html/rfc3550 section 5.1 (padding). At end of
+	// rtp packet, padding may exist, with the last octet being the length of the
+	// padding including itself.
 	if p.Padding != 0 {
 		buf = buf[:cap(buf)]
 		buf[len(buf)-1] = byte(p.Padding)