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Versions: (draft-cbran-rtcweb-codec) 00 01 02 03 04 05 06 RFC 7742

Network Working Group                                         A.B. Roach
Internet-Draft                                                   Mozilla
Intended status: Standards Track                           July 01, 2014
Expires: January 02, 2015


             WebRTC Video Processing and Codec Requirements
                       draft-ietf-rtcweb-video-00

Abstract

   This specification provides the requirements and consideration for
   WebRTC applications to send and receive video across a network.  It
   specifies the video processing that is required, codecs and their
   parameters, and types of RTP packetization that need to be supported.

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
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   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 January 02, 2015.

Copyright Notice

   Copyright (c) 2014 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
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Pre and Post Processing . . . . . . . . . . . . . . . . . . .   2
     3.1.  Camera Source Video . . . . . . . . . . . . . . . . . . .   3
     3.2.  Screen Source Video . . . . . . . . . . . . . . . . . . .   3
   4.  Codec Considerations  . . . . . . . . . . . . . . . . . . . .   3
     4.1.  VP8 . . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.2.  H.264 . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.3.  VP9 . . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     4.4.  H.265 . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Dealing with Packet Loss  . . . . . . . . . . . . . . . . . .   4
   6.  Mandatory to Implement Video Codec  . . . . . . . . . . . . .   4
     6.1.  Temperature of Working Group  . . . . . . . . . . . . . .   4
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   6
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   6
     10.2.  Informative References . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   One of the major functions of WebRTC endpoints is the ability to send
   and receive interactive video.  The video might come from a camera, a
   screen recording, a stored file, or some other source.  This
   specification defines how the video is used and discusses special
   considerations for processing the video.  It also covers the video-
   related algorithms WebRTC devices need to support.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

3.  Pre and Post Processing

   This section provides guidance on pre- or post-processing of video
   streams.

   Unless specified otherwise by the SDP or Codec, the color space
   SHOULD be TBD.

   TODO: What color space is our default?




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3.1.  Camera Source Video

   To support a quality experience with no application level adjustment
   from the Javascript running in the browsers, WebRTC endpoints are
   REQUIRED to support:

   o  Automatic focus, if applicable for the camera in use

   o  Automatic white balance

   o  Automatic light level control

   TODO: What other processing should be specified here?

3.2.  Screen Source Video

   If the video source is some portion of a computer screen (e.g.,
   desktop or application sharing), then the considerations in this
   section also apply.

   TODO: What do we need to specify here?

4.  Codec Considerations

   WebRTC endpoints are not required to support all the codecs in this
   section.

   However, to foster interoperability between endpoints that have
   codecs in common, if they do support one of the listed codecs, then
   they need to meet the requirements specified in the subsection for
   that codec.

   All codecs MUST support at least 10 frames per second (fps) and
   SHOULD support 30 fps.  All codecs MUST support a minimum resolution
   of 320X240.

   TODO: These are strawman values.  Are they adequate?

4.1.  VP8

   If VP8, defined in [RFC6386], is supported, then the endpoint MUST
   support the payload formats defined in [I-D.ietf-payload-vp8].  In
   addition it MUST support the 'bilinear' and 'none' reconstruction
   filters.

4.2.  H.264





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   If [H264] is supported, then the device MUST support the payload
   formats defined in [RFC6184].  In addition, they MUST support
   Constrained Baseline Profile Level 1.2, and they SHOULD support H.264
   Constrained High Profile Level 1.3.

   TODO: What packetization modes MUST be supported?

4.3.  VP9

   If VP9, as defined in [I-D.grange-vp9-bitstream], is supported, then
   the device MUST support the payload formats defined in TODO.

   TODO: The grange-vp9-bitstream draft does not really specify VP9 at
   all, is there a better reference?

4.4.  H.265

   If [H265] is supported, then the device MUST support the payload
   formats defined in [I-D.ietf-payload-rtp-h265].

5.  Dealing with Packet Loss

   This section provides recommendations on how to encode video to be
   robust to packet loss.

   TODO: What do we want to require in terms of FEC, RTX, interleaving,
   etc?

6.  Mandatory to Implement Video Codec

   Note: This section is here purely as a placeholder and there is not
   yet WG Consensus on Mandatory to Implement video codecs.  The WG has
   agreed not to discuss this topic until September 29, 2014 so that the
   WG can focus on getting other work done.  Please, save your comments
   on this topic until that time.

   The currently recorded working group consensus is that all
   implementations MUST support a single, specified mandatory-to-
   implement codec.  The remaining decision point is a selection of this
   single codec.

6.1.  Temperature of Working Group









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   To capture the conversation so far, this section summarizes the
   result of a straw poll that the working group undertook in December
   2013 and January 2014.  Respondants were asked to answer "Yes,"
   "Acceptable," or "No" for each option.  The options were collected
   from the working group at large prior to the initiation of the straw
   poll.

                                                       Yes  Acc  No
                                                       ---  ---  ---
    1. All entities MUST support H.264                 48%  11%  41%
    2. All entities MUST support VP8                   41%  17%  42%
    3. All entities MUST support both H.264 and VP8     9%  38%  53%
    4. Browsers MUST support both H.264 and VP8, other
       entities MUST support at least one of H.264
       and VP8                                         11%  34%  55%
    5. All entities MUST support at least one of
       H.264 and VP8                                   10%  16%  74%
    6. All entities MUST support H.261                  5%  23%  72%
    7. There is no MTI video codec                     12%  30%  58%
    8. All entities MUST support H.261 and allentities
       MUST support at least one of H.264 and VP8       4%  28%  68%
    9. All entities MUST support Theora                 7%  26%  67%
   10. All entities MUST implement at least two of
       {VP8, H.264, H.261}                              5%  30%  65%
   11. All entities MUST implement at least two of
       {VP8, H.264, H.263}                              5%  25%  70%
   12. All entities MUST support decoding using both
       H.264 and VP8, and MUST support encoding using
       at least one of H.264 or VP8                     7%  20%  73%
   13. All entities MUST support H.263                  6%  19%  75%
   14. All entities MUST implement at least two of
       {VP8, H.264, Theora}                             6%  27%  67%
   15. All entities MUST support decoding using Theora  1%  15%  84%
   16. All entities MUST support Motion JPEG            1%  25%  74%


7.  Security Considerations

   This specification does not introduce any new mechanisms or security
   concerns beyond what the other documents it references.  In WebRTC,
   video is protected using DTLS/SRTP.  A complete discussion of the
   security can be found in [I-D.ietf-rtcweb-security] and
   [I-D.ietf-rtcweb-security-arch].  Implementers should consider
   whether the use of variable bit rate video codecs are appropriate for
   their application based on [RFC6562].

8.  IANA Considerations




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   This document requires no actions from IANA.

9.  Acknowledgements

   The authors would like to thank <GET YOUR NAME HERE - PLEASE SEND
   COMMENTS>.  Thanks to Cullen Jennings for providing text and review.
   This draft includes text from draft-cbran-rtcweb-codec.

10.  References

10.1.  Normative References

   [H264]     ITU-T Recommendation H.264, "Advanced video coding for
              generic audiovisual services", April 2013.

   [H265]     ITU-T Recommendation H.265, "High efficiency video
              coding", April 2013.

   [I-D.grange-vp9-bitstream]
              Grange, A. and H. Alvestrand, "A VP9 Bitstream Overview",
              draft-grange-vp9-bitstream-00 (work in progress), February
              2013.

   [I-D.ietf-payload-rtp-h265]
              Wang, Y., Sanchez, Y., Schierl, T., Wenger, S., and M.
              Hannuksela, "RTP Payload Format for High Efficiency Video
              Coding", draft-ietf-payload-rtp-h265-04 (work in
              progress), May 2014.

   [I-D.ietf-payload-vp8]
              Westin, P., Lundin, H., Glover, M., Uberti, J., and F.
              Galligan, "RTP Payload Format for VP8 Video", draft-ietf-
              payload-vp8-11 (work in progress), February 2014.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4175]  Gharai, L. and C. Perkins, "RTP Payload Format for
              Uncompressed Video", RFC 4175, September 2005.

   [RFC4421]  Perkins, C., "RTP Payload Format for Uncompressed Video:
              Additional Colour Sampling Modes", RFC 4421, February
              2006.

   [RFC6184]  Wang, Y.-K., Even, R., Kristensen, T., and R. Jesup, "RTP
              Payload Format for H.264 Video", RFC 6184, May 2011.





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   [RFC6386]  Bankoski, J., Koleszar, J., Quillio, L., Salonen, J.,
              Wilkins, P., and Y. Xu, "VP8 Data Format and Decoding
              Guide", RFC 6386, November 2011.

   [RFC6562]  Perkins, C. and JM. Valin, "Guidelines for the Use of
              Variable Bit Rate Audio with Secure RTP", RFC 6562, March
              2012.

10.2.  Informative References

   [I-D.ietf-rtcweb-security-arch]
              Rescorla, E., "WebRTC Security Architecture", draft-ietf-
              rtcweb-security-arch-09 (work in progress), February 2014.

   [I-D.ietf-rtcweb-security]
              Rescorla, E., "Security Considerations for WebRTC", draft-
              ietf-rtcweb-security-06 (work in progress), January 2014.

Author's Address

   Adam Roach
   Mozilla
   \
   Dallas
   US

   Phone: +1 650 903 0800 x863
   Email: adam@nostrum.com






















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