AVTCORE Working Group B. Aboba INTERNET-DRAFT Microsoft Corporation Category: Informational Expires: October 11, 2023 11 April 2023 H.265 Profile for WebRTC draft-aboba-avtcore-hevc-webrtc-00.txt Abstract RFC 7742 defines WebRTC video processing and codec requirements, including guidance for endpoints supporting the VP8 and H.264 codecs, which are mandatory to implement. With support for H.265 under development in WebRTC browsers, the need has arisen to provide similar guidance for browsers desiring to support the (optional) H.265 codec, whose RTP payload format is defined in RFC 7798. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on October 11, 2023. Aboba, et. al Standards Track [Page 1] INTERNET-DRAFT H.265 Profile for WebRTC 11 April 2023 Copyright Notice Copyright (c) 2023 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2. H.265 Support . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Security Considerations . . . . . . . . . . . . . . . . . . . 4 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Normative References . . . . . . . . . . . . . . . . . . 4 5.2. Informative References . . . . . . . . . . . . . . . . . 5 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Aboba, et. al Standards Track [Page 2] INTERNET-DRAFT H.265 Profile for WebRTC 11 April 2023 1. Introduction "RTP Payload Format for High Efficiency Video Coding (HEVC)" [RFC7798] defines the encapsulation of H.265 within the Real-time Transport Protocol (RTP). While "WebRTC Video Processing and Codec Requirements" [RFC7742] provides guidance for endpoints supporting the mandatory to implement VP8 and H.264 codecs, it does not cover H.265. With H.265 support under development within WebRTC browsers, the need has arisen to profile [RFC7798] for WebRTC implementations choosing to support H.265. 1.1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. 2. H.265 Support WebRTC browsers and non-browsers MAY implement the H.265 video codec as described in [RFC7798] and [HEVC]. WebRTC browsers and non- browsers supporting H.265 MUST support receiving, and MAY support the ability to send H.265. For the [HEVC] codec, endpoints MUST support the payload formats defined in [RFC7798]. In addition, they MUST support Main Profile Level 3.1 (level-id=93) and SHOULD support Main Profile Level 4 (level-id=120). Implementations of the HEVC codec have utilized a wide variety of optional parameters. To improve interoperability, the following parameter settings are specified: level-id: Implementations MUST include this parameter within SDP and MUST interpret it when receiving it. max-fps, max-cpb, max-dpb, and max-br: These parameters allow the implementation to specify that they can support certain features of HEVC at higher rates and values than those signaled by their level (set with level-id). Implementations MAY include these parameters in their SDP, but they SHOULD interpret them when receiving them, allowing them to send the highest quality of video possible. sprop-vps, sprop-sps, sprop-pps, sprop-sei: HEVC allows sequence and Aboba, et. al Standards Track [Page 3] INTERNET-DRAFT H.265 Profile for WebRTC 11 April 2023 picture information to be sent both in-band and out-of-band. WebRTC implementations MUST signal this information in-band. This means that WebRTC implementations MUST NOT include these parameters in the SDP they generate. When the use of the video orientation (CVO) RTP header extension is not signaled as part of the SDP, H.265 implementations MAY send and SHOULD support proper interpretation of Display Orientation SEI messages. Unless otherwise signaled, implementations that use H.265 MUST encode and decode pixels with an implied 1:1 (square) aspect ratio. 3. Security Considerations This document is subject to the security considerations described in Section 7 of [RFC7742]. In addition to those security considerations, H.265 implementers are advised to take note of the "Security Considerations" Section 9 of [RFC7798], including requirements pertaining to SEI messages. 4. IANA Considerations This document does not require actions by IANA. 5. References 5.1. Normative References [HEVC] ITU-T, "High efficiency video coding", ITU-T Recommendation H.265, April 2013. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, . [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, July 2003, . [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. Norrman, "The Secure Real-time Transport Protocol (SRTP)", RFC 3711, DOI 10.17487/RFC3711, March 2004, . Aboba, et. al Standards Track [Page 4] INTERNET-DRAFT H.265 Profile for WebRTC 11 April 2023 [RFC7798] Wang, Y.K., Sanchez, Y., Schierl, T., Wenger, S. and M. M. Hannuksela, "RTP Payload Format for High Efficiency Video Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798, March 2016, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", RFC 8174, DOI 10.17487/RFC8174, May 2017, . 5.2. Informative References [RFC7742] Roach, A. B., "WebRTC Video Processing and Codec Requirements", RFC 7742, DOI 10.17487/RFC7742, March 2016, . Acknowledgments We would like to thank Stefan Wenger, Philipp Hancke, and Harald Alvestrand for their discussions of this problem space. Authors' Addresses Bernard Aboba Microsoft Corporation One Microsoft Way Redmond, WA 98052 United States of America Email: bernard.aboba@gmail.com Aboba, et. al Standards Track [Page 5]