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Versions: 00 01 02 03 04 05                                             
CLUE WG                                                          R. Even
Internet-Draft                                              Gesher Erove
Intended status: Standards Track                       February 13, 2012
Expires: August 16, 2012


               Mapping RTP streams to CLUE media captures
                   draft-even-clue-rtp-mapping-00.txt

Abstract

   This document describes mechanisms and recommended practice for
   mapping RTP media streams defined in SDP to CLUE media captures.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 16, 2012.

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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Mapping CLUE Media Captures to RTP streams  . . . . . . . . . . 3
   4.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 7







































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1.  Introduction

   Telepresence systems can send and receive multiple media streams.
   The CLUE framework [I-D.ietf-clue-framework] defines media captures
   as a source of Media, such as from one or more Capture Devices.  A
   Media Capture (MC) may be the source of one or more Media streams.  A
   Media Capture may also be constructed from other Media streams.  A
   middle box can express Media Captures that it constructs from Media
   streams it receives.

   SIP offer answer [RFC3264] uses SDP [RFC4566] to describe the
   RTP[RFC3550] media streams.  Each RTP stream has a payload type
   number and SSRC.  The content of the RTP stream is created by the
   encoder in the endpoint.  This may be an original content from a
   camera or a content created by an intermediary device like an MCU.

   The relation between the two descriptions is that the CLUE media
   capture defines some semantics describing the content of an RTP
   stream.

   This document discusses the relation between the CLUE media captures
   and the RTP streams and makes recommendations on how to co-relate
   between the two.


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[RFC2119] and
   indicate requirement levels for compliant RTP implementations.


3.  Mapping CLUE Media Captures to RTP streams

   The SDP description of the RTP streams provides among others the
   inforamtion about the encoding and decdoing capbilities of the media
   as well as tranpsort addresses for receiving the RTP streams and some
   channels capbilities like the maximum bandwidth available for the
   data.

   The CLUE MCs provide semantic information of the stream which may be
   spatial inforamtion like left camera or on its content like loudest
   speaker

   An RTP stream can have different content based on the MC desription.
   For example one video capture from a camera may capture a third of
   the room while another from the same camera may provide a zoom



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   version of the whole room.  These two media captures can be mapped to
   the same RTP stream.

   Using the video capture example from the framework document:

   o  VC0- (the camera-left camera stream, purpose=main, auto-
      switched:no

   o  VC1- (the center camera stream, purpose=main, auto-switched:no

   o  VC2- (the camera-right camera stream), purpose=main, auto-
      switched:no

   o  VC3- (the loudest panel stream), purpose=main, auto-switched:yes

   o  VC4- (the loudest panel stream with PiPs), purpose=main,
      composed=true; auto-switched:yes

   o  VC5- (the zoomed out view of all people in the room),
      purpose=main, composed=no; auto-switched:no

   o  VC6- (presentation stream), purpose=presentation, auto-switched:no

   Where the physical simultaneity information is:

      {VC0, VC1, VC2, VC3, VC4, VC6}

      {VC0, VC2, VC5, VC6}

   To describe the MCs need 6 RTP streams since the first simultenous
   entry defines 6 streams.  The RTP stream used for VC1 is also the RTP
   stream for VC5 coming from the same camera.  This mapping from a
   Media capture to an RTP stream is fixed.  The number of RTP streams
   depends on the maximum number of captures in one capture set entry
   from the capture set.

   This mapping can be done by defining a new [RFC5888] grouping
   attribute CaptureId and a new CLUE MC attribute RTP-id.

   The above exmaple will have the following SDP

         a=group:captureId 1 2 3 4 5 6

         m=video 49170 RTP/AVP 96

         a=rtpmap:96 H264/90000





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         mid=1

         m=video 49172 RTP/AVP 96

         a=rtpmap:96 H264/90000

         mid=2

         m=video 49174 RTP/AVP 96

         a=rtpmap:96 H264/90000

         mid=3

         m=video 49176 RTP/AVP 96

         a=rtpmap:96 H264/90000

         mid=4

         m=video 49178 RTP/AVP 96

         a=rtpmap:96 H264/90000

         mid=5

         m=video 49180 RTP/AVP 96

         a=rtpmap:96 H264/90000

         mid=6

   There is a need for a new MC attribute RTPid which will have the mid
   of the related RTP stream

   o  VC0- (the camera-left camera stream, purpose=main, auto-
      switched:no, RTPid=1

   o  VC1- (the center camera stream, purpose=main, auto-switched:no,
      RTPid=2

   o  VC2- (the camera-right camera stream), purpose=main, auto-
      switched:no, RTPid=3

   o  VC3- (the loudest panel stream), purpose=main, auto-switched:yes,
      RTPid=4





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   o  VC4- (the loudest panel stream with PiPs), purpose=main,
      composed=true; auto-switched:yes, RTPid=5

   o  VC5- (the zoomed out view of all people in the room),
      purpose=main, composed=no; auto-switched:no, RTPid=2

   o  VC6- (presentation stream), purpose=presentation, auto-
      switched:no, RTPid=6

   This will allow to provide different encdoing parameters to each MC
   and leverage other grouping defined like bundle.


4.  Acknowledgements

   place holder


5.  IANA Considerations

   TBD


6.  Security Considerations

   TBD.


7.  References

7.1.  Normative References

   [I-D.ietf-clue-framework]
              Romanow, A., Duckworth, M., Pepperell, A., and B. Baldino,
              "Framework for Telepresence Multi-Streams",
              draft-ietf-clue-framework-03 (work in progress),
              February 2012.

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

7.2.  Informative References

   [RFC3264]  Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
              with Session Description Protocol (SDP)", RFC 3264,
              June 2002.

   [RFC3550]  Schulzrinne, H., Casner, S., Frederick, R., and V.



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              Jacobson, "RTP: A Transport Protocol for Real-Time
              Applications", STD 64, RFC 3550, July 2003.

   [RFC4566]  Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
              Description Protocol", RFC 4566, July 2006.

   [RFC5888]  Camarillo, G. and H. Schulzrinne, "The Session Description
              Protocol (SDP) Grouping Framework", RFC 5888, June 2010.


Author's Address

   Roni Even
   Gesher Erove
   Tel Aviv,
   Israel

   Email: ron.even.tlv@gmail.com

































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