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Versions: 00 01 02 draft-ietf-rtcweb-video

Network Working Group                                            C. Bran
Internet-Draft                                               C. Jennings
Intended status: Standards Track                                   Cisco
Expires: December 30, 2011                                 June 28, 2011


            RTC-Web Codec and Media Processing Requirements
                      draft-cbran-rtcweb-codec-00

Abstract

   This document outlines the codec and media processing requirements
   for RTC-Web client application and endpoint devices.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.  This document may not be modified,
   and derivative works of it may not be created, and it may not be
   published except as an Internet-Draft.

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   This Internet-Draft will expire on December 30, 2011.

Copyright Notice

   Copyright (c) 2011 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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   described in the Simplified BSD License.




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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Codec Requirements  . . . . . . . . . . . . . . . . . . . . . . 3
     3.1.  Audio Codec Requirements  . . . . . . . . . . . . . . . . . 3
     3.2.  Video Codec Requirements  . . . . . . . . . . . . . . . . . 4
   4.  RTC-Web Endpoint Device Requirements  . . . . . . . . . . . . . 5
   5.  Legacy VoIP Interoperability  . . . . . . . . . . . . . . . . . 5
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   7.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   9.  Normative References  . . . . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 6





































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1.  Introduction

   An integral part of the success and adoption of the Real-Time
   Communications Web (RTC-WEB) will be the interoperability between
   RTC-Web applications.  This specification will focus on the media
   processing and codec requirements for RTC-Web client applications.

   Media processing and codec requirements fit into a series of
   specifications have been created to address RTC-Web communications
   protocols, security requirements, data transmission and use cases.
   More information on the RTC-Web can be found here:

   [TODO put links to supporting drafts here]


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 RFC 2119 [RFC2119].


3.  Codec Requirements

   This section covers the audio and video codec requirements for RTC-
   WEB client applications.  To ensure a baseline level of
   interoperability between RTC-Web applications, a minimum set of
   required codes is specified below.  While this section specifies the
   codecs that will be supported by all RTC-Web application
   implementations, it leaves the question of supporting additional
   codecs to the will of the implementer.

3.1.  Audio Codec Requirements

   RTC-WEB applications are REQUIRED to implement the following audio
   codecs.

   o  PCMA/PCMU - see section 4.5.14 of [RFC3551]

   o  Telephone-event - [RFC4734]

   o  Opus [draft-ietf-codec-opus]

   Implementations of the PCMU and PMCA codecs are REQUIRED to support 1
   channel with a rate of 8000 and a ptime of 20.

   The following codecs are OPTIONAL for RTC-WEB application
   implementations.



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   o  G729

   o  G722

   o  G722.1

   o  G723

   o  AMR

   o  AMR-WB

   o  iLBC

   o  L16

   [Open Issue: minimum profile and identifying any additional mandatory
   to implement audio codecs.]

3.2.  Video Codec Requirements

   RTC-WEB applications are REQUIRED to implement the following video
   codecs.

   o  VP8 [I-D.webm]

   The following feature list applies to all required video codecs.

   Required video codecs:

   o  MUST support at least 10 frames per second (fps) and SHOULD
      support 30 fps

   o  MUST support a the bilinear and none reconstruction filters

   o  OPTIONALLY offer support for additional color spaces

   o  MUST support a minimum resolution of 320X240

   o  SHOULD support resolutions of 1280x720, 720x480, 1024x768,
      800x600, 640x480, 640 x 360 , 320x240

   The following video codecs are OPTIONAL for RTC-WEB application
   implementations.

   o  H.263





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   o  H.264-AVC

   o  H.264-SVC


4.  RTC-Web Endpoint Device Requirements

   It is plausible that the dominant near-to-mid term RTC-Web usage
   model will be people using the RTC-Web functionality to communicate
   with each other via web browsers typically running within a notebook
   computer that has built-in microphone and speakers.  The notebook-as-
   communication-device paradigm presents challenging echo cancellation
   and audio gain problems, the specific remedy of which will not be
   mandated here.  However, while no specific algorithm or standard will
   be required by RTC-Web compatible endpoints, it has been found that
   functionality such as automatic gain control, echo cancellation, and
   headset detection will improve the user experience and should be
   implemented by the endpoint device.

   To address the problems outlined above, suitable implementations of
   the functionality listed below SHOULD be available within an RTC-Web
   endpoint device.

   o  Automatic gain control

   o  Echo cancellation, including acoustic echo cancelation

   o  Headset detection

   o  Auto-adjustments to gain control and echo cancelation algorithms
      based on if headset or internal speakers/microphone is being used


5.  Legacy VoIP Interoperability

   The codec requirements above will ensure, at a minimum, voice
   interoperability capabilities between RTC-Web client applications and
   legacy phone systems.

   Video interoperability will be dependent upon the support, natively
   or through transcoding, of VP8 by the phone system vendors or the
   availability of an interoperable codec, such as H.264-AVC, from
   within the RTC-Web client application implementation.


6.  IANA Considerations

   This document makes no request of IANA.



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   Note to RFC Editor: this section may be removed on publication as an
   RFC.


7.  Security Considerations

   The codec requirements have no additional security considerations
   other than those captured in
   [I-D.ekr-security-considerations-for-rtc-web].


8.  Acknowledgements

   This draft incorporates ideas and text from various other drafts.  In
   particularly we would like to acknowledge, and say thanks for, work
   we incorporated from Harald Alvestrand.


9.  Normative References

   [I-D.ekr-security-considerations-for-rtc-web]
              Rescorla, E., "Security Considerations for RTC-Web",
              May 2011.

   [I-D.webm]
              Google, Inc., "VP8 Data Format and Decoding Guide",
              July 2010.

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

   [RFC3551]  Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
              Video Conferences with Minimal Control", STD 65, RFC 3551,
              July 2003.

   [RFC4734]  Schulzrinne, H. and T. Taylor, "Definition of Events for
              Modem, Fax, and Text Telephony Signals", RFC 4734,
              December 2006.













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Authors' Addresses

   Cary Bran
   Cisco
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   Phone: +1 206 256-3502
   Email: cbran@cisco.com


   Cullen Jennings
   Cisco
   170 West Tasman Drive
   San Jose, CA  95134
   USA

   Phone: +1 408 421-9990
   Email: fluffy@cisco.com































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