rfc9627v5.txt   rfc9627.txt 
Internet Engineering Task Force (IETF) J. Lennox Internet Engineering Task Force (IETF) J. Lennox
Request for Comments: 9627 8x8 / Jitsi Request for Comments: 9627 8x8 / Jitsi
Category: Standards Track D. Hong Category: Standards Track D. Hong
ISSN: 2070-1721 Google ISSN: 2070-1721 Google
J. Uberti J. Uberti
OpenAI OpenAI
S. Holmer S. Holmer
M. Flodman M. Flodman
Google Google
February 2025 March 2025
The Layer Refresh Request (LRR) RTCP Feedback Message The Layer Refresh Request (LRR) RTCP Feedback Message
Abstract Abstract
This memo describes the RTCP Payload-Specific Feedback Message Layer This memo describes the RTCP Payload-Specific Feedback Message Layer
Refresh Request (LRR), which can be used to request a state refresh Refresh Request (LRR), which can be used to request a state refresh
of one or more substreams of a layered media stream. This document of one or more substreams of a layered media stream. This document
also defines its use with several RTP payloads for scalable media also defines its use with several RTP payloads for scalable media
formats. formats.
skipping to change at line 114 skipping to change at line 114
depend both on earlier pictures of that spatial layer and also on depend both on earlier pictures of that spatial layer and also on
lower-layer pictures of the current picture. However, a layer lower-layer pictures of the current picture. However, a layer
refresh typically requires that a spatial-layer picture be encoded in refresh typically requires that a spatial-layer picture be encoded in
a way that references only the lower-layer subpictures of the current a way that references only the lower-layer subpictures of the current
picture, not any earlier pictures of that spatial layer. picture, not any earlier pictures of that spatial layer.
Additionally, the encoder must promise that no earlier pictures of Additionally, the encoder must promise that no earlier pictures of
that spatial layer will be used as reference in the future. that spatial layer will be used as reference in the future.
However, even in a layer refresh, layers other than the ones being However, even in a layer refresh, layers other than the ones being
refreshed may still maintain dependency on earlier content of the refreshed may still maintain dependency on earlier content of the
stream. This is the difference between a layer refresh and an FIR stream. This is the difference between a layer refresh and a FIR
[RFC5104]. This minimizes the coding overhead of refresh to only [RFC5104]. This minimizes the coding overhead of refresh to only
those parts of the stream that actually need to be refreshed at any those parts of the stream that actually need to be refreshed at any
given time. given time.
The spatial-layer refresh of an enhancement layer is shown below. The spatial-layer refresh of an enhancement layer is shown below.
The "<--" indicates a coding dependency. The "<--" indicates a coding dependency.
... <-- S1 <-- S1 S1 <-- S1 <-- ... ... <-- S1 <-- S1 S1 <-- S1 <-- ...
| | | | | | | |
\/ \/ \/ \/ \/ \/ \/ \/
skipping to change at line 607 skipping to change at line 607
M. Hannuksela, "RTP Payload Format for High Efficiency M. Hannuksela, "RTP Payload Format for High Efficiency
Video Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798, Video Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798,
March 2016, <https://www.rfc-editor.org/info/rfc7798>. March 2016, <https://www.rfc-editor.org/info/rfc7798>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9626] Zanaty, M., Berger, E., and S. Nandakumar, "Video Frame [RFC9626] Zanaty, M., Berger, E., and S. Nandakumar, "Video Frame
Marking RTP Header Extension", RFC 9626, Marking RTP Header Extension", RFC 9626,
DOI 10.17487/RFC9626, February 2025, DOI 10.17487/RFC9626, March 2025,
<https://www.rfc-editor.org/info/rfc9626>. <https://www.rfc-editor.org/info/rfc9626>.
9.2. Informative References 9.2. Informative References
[RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and [RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and
B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms
for Real-Time Transport Protocol (RTP) Sources", RFC 7656, for Real-Time Transport Protocol (RTP) Sources", RFC 7656,
DOI 10.17487/RFC7656, November 2015, DOI 10.17487/RFC7656, November 2015,
<https://www.rfc-editor.org/info/rfc7656>. <https://www.rfc-editor.org/info/rfc7656>.
[RFC8082] Wenger, S., Lennox, J., Burman, B., and M. Westerlund, [RFC8082] Wenger, S., Lennox, J., Burman, B., and M. Westerlund,
"Using Codec Control Messages in the RTP Audio-Visual "Using Codec Control Messages in the RTP Audio-Visual
Profile with Feedback with Layered Codecs", RFC 8082, Profile with Feedback with Layered Codecs", RFC 8082,
DOI 10.17487/RFC8082, March 2017, DOI 10.17487/RFC8082, March 2017,
<https://www.rfc-editor.org/info/rfc8082>. <https://www.rfc-editor.org/info/rfc8082>.
[RFC9628] Lennox, J., Hong, D., Uberti, J., Holmer, S., and M. [RFC9628] Uberti, J., Holmer, S., Flodman, M., Hong, D., and J.
Flodman, "The Layer Refresh Request (LRR) RTCP Feedback Lennox, "RTP Payload Format for VP9 Video", RFC 9628,
Message", RFC 9628, DOI 10.17487/RFC9628, February 2025, DOI 10.17487/RFC9628, March 2025,
<https://www.rfc-editor.org/info/rfc9628>. <https://www.rfc-editor.org/info/rfc9628>.
Authors' Addresses Authors' Addresses
Jonathan Lennox Jonathan Lennox
8x8, Inc. / Jitsi 8x8, Inc. / Jitsi
Jersey City, NJ 07302 Jersey City, NJ 07302
United States of America United States of America
Email: jonathan.lennox@8x8.com Email: jonathan.lennox@8x8.com
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