Guidance on RPSI implementation

Fix for Issue #13

hevc-webrtc-04.nr

@@ -149,6 +149,18 @@ not signaled as part of the SDP, H.265 implementations MAY send and
 SHOULD support proper interpretation of Display Orientation SEI
 messages.
 
+[RFC7798] Section 8.3 specifies the use of the Reference Picture Selection
+Indication (RPSI) in H.265. As noted in "Media Transport and Use of RTP in WebRTC"
+[RFC8834] Section 5.1.4:
+
+.in +0.3i
+Receivers that detect that encoder-decoder synchronization has been lost SHOULD
+generate an RPSI feedback message if the codec being used supports reference-picture
+selection. An RTP packet-stream sender that receives such an RPSI message SHOULD
+act on that messages to change the reference picture, if it is possible to do
+so within the available bandwidth constraints and with the codec being used.
+.in -0.3i
+
 Unless otherwise signaled, WebRTC implementations that support H.265 MUST encode
 and decode pixels with an implied 1:1 (square) aspect ratio.
 .in -0.3i
@@ -202,6 +214,10 @@ RFC 7798, DOI 10.17487/RFC7798, March 2016,
 Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words",
 RFC 8174, DOI 10.17487/RFC8174, May 2017,
 <https://www.rfc-editor.org/info/rfc8174>.
+.IP [RFC8834]
+Perkins, C., Westerlund, M. and J. Ott., "Media Transport and Use of
+RTP in WebRTC", RFC 8834, DOI 10.17487/RFC8834, January 2021,
+<https://www.rfc-editor.org/info/rfc8834>.
 .NH 2
 .R
 Informative References