Internet DRAFT - draft-deng-rtcweb-codecapi

draft-deng-rtcweb-codecapi







Network Working Group                                            L. Deng
Internet-Draft                                                     L. Ni
Intended status: Informational                                     Q. Yu
Expires: January 09, 2014                                   China Mobile
                                                           July 08, 2013


        Proposal for reusing local codec APIs on mobile devices
                   draft-deng-rtcweb-codecapi-00.txt

Abstract

   This document proposes the browser to make use of local codec APIs,
   if available on a mobile device, and notifies RTCWEB applications to
   allow for better tuning between device capability and media quality.

Status of This Memo

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   This Internet-Draft will expire on January 09, 2014.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .   2
     2.1.  Built-in media capabilities in mobile devices . . . . . .   2
     2.2.  MTI codecs for mobile devices?  . . . . . . . . . . . . .   3
   3.  Proposal  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Function Requirement for Browser  . . . . . . . . . . . .   4
     3.2.  API Requirements for Browser  . . . . . . . . . . . . . .   4
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .   4
     6.2.  Informative References  . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   It is expected that by including the built-in real-time communication
   capabilities into a general purpose browser, the development and
   integration of person-to-person communication experience into a web
   page, without pre-installation of any additional software.

   There has been extensive discussion on the MTI video codec for RTCWEB
   browsers for quite a period of time.  Whereas so far the discussion
   has mainly focused on evaluating one against another based on merits
   as well as IPR issues.

2.  Discussion

2.1.  Built-in media capabilities in mobile devices

   Unlike general purpose personal computers, smart phones have built-in
   support for audio/video encoding/decoding functionalities, as their
   traditional role is to serve as a phone.

   Considering other types of mobile devices, like Wifi-only tablets,
   users are increasingly expect that they also provide real-time media
   channels in one way or another.  For instance, watching streaming
   clips from a web page, or chatting with family members and friends
   through VoIP applications.

   In all, it is expected that a mobile device provides some sort of
   built-in media processing capabilities in the first place.  For
   instance, Android system provides various media encoding/decoding
   support [android-codec-support].  IOS platforms also supply hardware-
   accelerated codec APIs for built-in codecs [apple-codec-support].




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2.2.  MTI codecs for mobile devices?

   We made the following observations on this point for mobile devices:

   o  A couple of MTI codecs may not be sufficient for a general purpose
      browser targeting the mobile users.

   On the one hand, a user's expected/perceived media quality of a real-
   time communication applications, which is largely dependent on the
   device in hand and the type of service they are using, is hardly
   possible to be covered by a handful of MTI codecs.

   To begin with, as different devices vary in size of screen, hence a
   HD video stream, which would be appreciated for a tablet user, could
   turn out to be a waste of resources for a smaller-screened smart
   phone.

   Furthermore, considering the case of interworking, it is almost
   always better to use the same choice of codec as the other end than
   to choose another one and to do trans-coding in between.

   o  A universal package of codecs is not cost-effective for mobile
      browsers.

   Despite the rapid increase in processing power and wireless
   bandwidth, portal mobile devices are bonded by short-lived battery
   power and physical size, it would not be wise for a mobile browser to
   include the bunch of all the potentially needed codecs.  Since this
   would consume much more resources and expand the installing package
   as well.  What's worse, it could mean extra expense for the browser
   vender to include each patented codec algorithm.

3.  Proposal

   In summary, we believe it could be desirable for the browser to make
   use of local media support provided by the end device system into the
   candidate pool for various web applications to choose for their
   specific RTCWEB usage cases and differential quality expectations
   accordingly.  Because reusing the local codec support has the
   following advantages:

   o  It reduces the implementation complexity and potential patent cost
      for general purpose browsers.
   o  It would eliminate the risk of degrading user experience when
      compared with other real-time communication applications using the
      same local facility.

   Specifically, the indicated requirements are two-folded:



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3.1.  Function Requirement for Browser

   Firstly, a RTCWEB-compatible browser MAY make use of codec APIs
   supported by a mobile device locally be default and include them into
   SDP offer/answer exchange with the other end.

3.2.  API Requirements for Browser

   Moreover, it SHOULD be possible for the JS to be able to distinguish
   the locally supported codecs from the other browser-bounded ones, and
   be allowed to make proper choices based on the specific communicating
   scenario in question.

4.  Security Considerations

   TBA

5.  IANA Considerations

   None.

6.  References

6.1.  Normative References

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

   [RFC2234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", RFC 2234, November 1997.

6.2.  Informative References

   [android-codec-support]
              , "http://developer.android.com/guide/appendix/media-
              formats.html#core", .

   [apple-codec-support]
              , "https://developer.apple.com/library/ios/#documentation/
              AudioVideo/Conceptual/AVFoundationPG/Articles/
              00_Introduction.html#//apple_ref/doc/uid/TP40010188", .

Authors' Addresses

   Lingli Deng
   China Mobile

   Email: denglingli@chinamobile.com



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   Lingfei Ni
   China Mobile

   Email: nilingfei@chinamobile.com


   Qing Yu
   China Mobile

   Email: yuqing@chinamobile.com









































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