Internet DRAFT - draft-aboba-avtcore-hevc-webrtc

draft-aboba-avtcore-hevc-webrtc









AVTCORE Working Group                                           B. Aboba
INTERNET-DRAFT                                                 P. Hancke
Category: Standards Track                          Microsoft Corporation
Expires: April 13, 2024                                  13 October 2023


                        H.265 Profile for WebRTC
                 draft-aboba-avtcore-hevc-webrtc-02.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, similar guidance is needed for
   browsers considering support for the 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
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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on April 13, 2024.

















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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 . . . . . . . . . . . . . . . . . . . . .   5
   5. References . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   5
   Acknowledgments   . . . . . . . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

























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1.  Introduction

   "RTP Payload Format for High Efficiency Video Coding (HEVC)"
   [RFC7798] defines the encapsulation of H.265 [H.265] within the Real-
   time Transport Protocol (RTP) [RFC3550].  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
   browsers [HEVC-WebKit][HEVC-Chrome] there is a need to for an
   interoperability profile of [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

   Support for the H.265 video codec is OPTIONAL for WebRTC browsers and
   non-browsers.  Implementations supporting H.265 that conform to this
   specification MUST support receiving H.265 and MAY support sending
   H.265.

   For the H.265 [H.265] 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).

   [RFC7798] Section 4.5 defines how Temporal Scalability Control
   Information (TSCI) is communicated using PACI Extensions defined in
   [RFC7798] Section 4.4.4.2.  A WebRTC implementation that has
   negotiated use of RTP header extensions containing TSCI information
   (such as the Dependency Descriptor [DD]) SHOULD NOT send TSCI
   information within the PACI.  If TSCI information is being received
   in an RTP header extension, implementations MUST ignore TSCI
   information contained in the PACI.

   Implementations of the H.265 codec have utilized a wide variety of
   optional parameters.  To improve interoperability, the following
   parameter settings are specified:

   level-id: Implementations SHOULD include this parameter within SDP
   and MUST interpret it when receiving it. If no level-id is present, a
   value of 93 (i.e., level 3.1) MUST be inferred.



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   tx-mode: Implementations SHOULD NOT include this parameter within
   SDP.  If no tx-mode parameter is present, a value of "SRST" MUST be
   inferred.  Implementations MUST support "SRST"; support for "MRST"
   and "MRMT" is OPTIONAL. Implementations that do not support "MRST" or
   "MRMT" MUST NOT include these tx-mode values in SDP.

   sprop-sps, sprop-pps, sprop-vps, sprop-sei: H.265 allows sequence and
   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, and SHOULD silently ignore these parameters if
   they are received. An IDR sent MUST always be preceded by the
   relevant parameter sets sent in a packet (not necessarily a separate
   packet) with the same RTP timestamp as the IDR.

   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.

   [RFC7798] Section 8.3 specifies the use of the Reference Picture
   Selection Indication (RPSI) in H.265. Implementations MUST use the
   RPSI feedback message only as a reference picture selection request,
   and MUST NOT use it as positive acknowledgement. Receivers that
   detect that H.265 encoder-decoder synchronization has been lost
   SHOULD generate an RPSI feedback message if support for RPSI has been
   negotiated, unless the receiver has knowledge that the sender does
   not support RPSI. Such knowledge can be established during capability
   exchange or through previously sent RPSI requests that were not
   replied to by the sender through the use of a non-IRAP picture.  An
   RTP packet-stream sender that receives an RPSI message MUST act on
   that message, and SHOULD change the reference picture.

   Unless otherwise signaled, WebRTC implementations that support 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.






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4.  IANA Considerations

   This document does not require actions by IANA.

5.  References

5.1.  Normative References

[DD]           Alliance for Open Media (AoMedia), "Dependency Descriptor
               RTP Header Extension",
               https://aomediacodec.github.io/av1-rtp-spec/#dependency-
               descriptor-rtp-header-extension, retrieved September 19,
               2023.

[H.265]        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, <https://www.rfc-
               editor.org/info/rfc2119>.

[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, <https://www.rfc-editor.org/info/rfc3550>.

[RFC7742]      Roach, A. B., "WebRTC Video Processing and Codec
               Requirements", RFC 7742, DOI 10.17487/RFC7742, March
               2016, <https://www.rfc-editor.org/info/rfc7742>.

[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, <https://www.rfc-editor.org/info/rfc7798>.

[RFC8174]      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>.

5.2.  Informative References

[HEVC-WebKit]  Shin, S. Qiu, J. and J. Zhu, "WebRTC HEVC RFC 7798 RTP
               Payload Format Implementation",
               https://github.com/WebKit/WebKit/pull/15494 (work in
               progress), retrieved July 9, 2023.





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[HEVC-Chrome]  "Issue 13485: Need the support of H.265",
               https://bugs.chromium.org/p/webrtc/issues/detail?
               id=13485 (work in progress), submitted December 8, 2021.

Acknowledgments

   We would like to thank Stephan Wenger, Jonathan Lennox, Harald
   Alvestrand, Jianlin Qiu and Philip Eliasson 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

   Philipp Hancke
   Microsoft Corporation
   Talinn, Estonia

   Email: philipp.hancke@gmail.com


























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