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. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any 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 August 16, 2012. Copyright Notice Copyright (c) 2012 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 (http://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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Even Expires August 16, 2012 [Page 1] Internet-Draft RTP mapping to CLUE February 2012 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 Even Expires August 16, 2012 [Page 2] Internet-Draft RTP mapping to CLUE February 2012 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 Even Expires August 16, 2012 [Page 3] Internet-Draft RTP mapping to CLUE February 2012 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 Even Expires August 16, 2012 [Page 4] Internet-Draft RTP mapping to CLUE February 2012 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 Even Expires August 16, 2012 [Page 5] Internet-Draft RTP mapping to CLUE February 2012 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. Even Expires August 16, 2012 [Page 6] Internet-Draft RTP mapping to CLUE February 2012 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 Even Expires August 16, 2012 [Page 7]