MMUSIC O. Levin Internet-Draft Microsoft Corporation Intended status: Informational R. Even Expires: July 18, 2007 Polycom P. Hagendorf RADVISION January 14, 2007 XML Schema for Media Control draft-levin-mmusic-xml-media-control-08 Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on July 18, 2007. Copyright Notice Copyright (C) The Internet Society (2007). Abstract This document defines an XML Schema for video fast update in a tightly controlled environment, developed by Microsoft, Polycom, Radvision and used by multiple vendors. This document describes a method that has been deployed in SIP based systems for over the last three years and being used across real-time interactive applications Levin, et al. Expires July 18, 2007 [Page 1] Internet-Draft Media Control January 2007 from different vendors in interoperable manner. New implementations are discouraged from using the described method described except for backward compatibility purposes. New Implementations are required to use the new full intra request command in the RTCP channel. Table of Contents 1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Background . . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. The Video Control Commands . . . . . . . . . . . . . . . . . . 4 5. The Schema Definition . . . . . . . . . . . . . . . . . . . . 4 6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . . 6 7. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 7.1. The Fast Update command for the full picture . . . . . . . 6 7.2. Reporting an error . . . . . . . . . . . . . . . . . . . . 6 8. Transport . . . . . . . . . . . . . . . . . . . . . . . . . . 7 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 10. URN for XML schema . . . . . . . . . . . . . . . . . . . . . . 8 11. Security Considerations . . . . . . . . . . . . . . . . . . . 9 12. Changes History . . . . . . . . . . . . . . . . . . . . . . . 9 12.1. Changes since -04 . . . . . . . . . . . . . . . . . . . . 9 12.2. Changes since -03 . . . . . . . . . . . . . . . . . . . . 9 12.3. Changes since -02 . . . . . . . . . . . . . . . . . . . . 9 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 10 13.1. Normative References . . . . . . . . . . . . . . . . . . . 10 13.2. Informative References . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Intellectual Property and Copyright Statements . . . . . . . . . . 12 Levin, et al. Expires July 18, 2007 [Page 2] Internet-Draft Media Control January 2007 1. Conventions 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 [3]. 2. Introduction This document defines an XML Schema for video fast update request in a tightly controlled environment, developed by Microsoft, Polycom, Radvision and used by multiple vendors. Implementation of this schema for interactive video applications in SIP [6] environments was designed in order to improve user experience. This mechanism is being used by both end user video conferencing terminals and conferencing servers in shipping products. This document describes the current method, but new implementations are discouraged from using this method, except for backward compatibility with legacy systems. Shipping products and new products SHALL use the full intra request described in [9]. Sending video fast update using the SIP signaling path, as described in this document, is inferior to using the RTCP feedback method[9], since the command flows through all the proxies in the signaling path adding delay to the messages and causing unnecessary overload to the proxies. RTCP messages flow end to end and not through the signaling proxies. The RTCP feedback draft[9] also adds other required control functions, such as flow control command which is missing from this document. 3. Background SIP typically uses RTP [7] for transferring of real time media. RTP is augmented by a control protocol (RTCP) to allow monitoring of the data delivery in a manner scalable to large multicast networks. The RTCP feedback mechanism [10] has been introduced in order to improve basic RTCP feedback time in case of loss conditions across different coding schemes. (Previously, a subset of this functionality was defined for H.261 [2] only). Theses techniques address signaling of loss conditions and the recommended recovery steps. Just recently an extension to the feedback mechanism has been proposed [9] to express control operations on media streams as a result of application logic rather than a result of loss conditions. Note that in the decomposed systems the implementation of the new Levin, et al. Expires July 18, 2007 [Page 3] Internet-Draft Media Control January 2007 mechanism will require proprietary communications between the applications/call control components and the media components. This document describes a technology that has been deployed in SIP based systems for over the last three years and being used across real-time interactive applications from different vendors in interoperable manner. This memo documents this technology for the purpose of describing current practice and new implementation MUST use the RTCP full intra request command specified in the RTCP based codec control messages document[9]. 4. The Video Control Commands Output of a video CODEC is a frame. The frame can carry complete (in time) information about a picture or about a picture segment. These frames are known as "Intra" frames. In order to save bandwidth, other frames can carry only changes relative to previously sent frames. Frames carrying relative information are known as "Inter" frames. Based on application logic (such as need to present a new video source), the application needs to have an ability to explicitly request from a remote encoder the complete (in-time) information about a "full" picture. The fast update command, defined in this document, MUST be validated by the remote entity against current media capacity and network conditions before being executed. In order to meet the presented requirements, a video primitive is defined by this document. The following command is sent to the remote encoder: o Video Picture Fast Update 5. The Schema Definition Levin, et al. Expires July 18, 2007 [Page 4] Internet-Draft Media Control January 2007 Levin, et al. Expires July 18, 2007 [Page 5] Internet-Draft Media Control January 2007 6. Error Handling Currently, only a single general error primitive is defined. It MAY be used for indicating errors in free text format. The general error primitive MAY report problems regarding XML document parsing, inadequate level of media control support, inability to perform the requested action, etc. The general error primitive MUST NOT be used for indication of errors other than related to media control parsing or to resultant execution. The general error primitive MUST NOT be sent back as a result of getting an error primitive. 7. Examples 7.1. The Fast Update command for the full picture In the following example the full picture "Fast Update" command is issued towards the remote video decoder(s). Note that this primitive is supported by all known implementations. 7.2. Reporting an error If an error occurs during the parsing of the XML document, the following XML document would be sent back to the originator of the original Media Control document. Parsing error: The original XML segment is:... Levin, et al. Expires July 18, 2007 [Page 6] Internet-Draft Media Control January 2007 8. Transport The defined XML document is conveyed using SIP INFO method [4] with the "Content-Type" set to "application/media_control+xml". This approach benefits from the SIP built-in reliability. This document registers the defined schema with IANA according to the guidelines specified in [8] . 9. IANA Considerations Application/media_control+xml MIME type MIME Media Type Name: application MIME subtype name: media_control+xml Required parameters: None Optional parameters: charset See RFC 3023 [5] for a discussion of the charset parameter on XML- derived MIME types. Since this MIME type is used exclusively in SIP, the use of UTF-8 encoding is strongly encouraged. Encoding considerations: 8-bit text Security considerations: Security considerations specific to uses of this MIME type are discussed in RFC xxxx [[Note to RFC editor: replace xxxx with the RFC number of this document when published]]. RFC 1874 [1] and RFC 3023 [5] discuss security issues common to all uses of XML. Interoperability considerations: The use of this MIME body is intended to be generally interoperable. No unique considerations have been identified. Published specification: RFC xxxx [[Note to RFC editor: replace xxxx with the RFC number of this document when published]] Applications which use this media type: This media type is used to convey information regarding media control commands and responses between SIP endpoints particularly for allowing a Video Fast Update intra-frame request. Additional information: Magic Number(s): None. Levin, et al. Expires July 18, 2007 [Page 7] Internet-Draft Media Control January 2007 File Extension(s): None. Macintosh File Type Code(s): None. Object Identifier(s) or OID(s): None. Intended usage: Limited Use Other Information/General Comment: None. Person to contact for further information: Name: Orit Levin E-Mail: oritl@microsoft.com Author/Change Controller: IETF MMUSIC working group, delegated from the IESG. The specification of this MIME type is an individual submission to the MMUSIC working group of the IETF. Change control of this specification is under control of the IETF WG. 10. URN for XML schema URI: urn:ietf:params:xml:ns:media_control Description: This is the XML namespace URI for XML elements defined by [RFCXXXX] to describe information exchanged between SIP endpoints for media control. It is used in the application/media_control+xml body type. Registrant Contact: Name: Orit Levin E-Mail: oritl@microsoft.com Author/Change Controller: IETF MMUSIC working group, delegated from the IESG. The specification of this MIME type is an individual submission to the MMUSIC working group of the IETF. Change control of this specification is under control of the IETF WG. XML: Levin, et al. Expires July 18, 2007 [Page 8] Internet-Draft Media Control January 2007 BEGIN Namespace for Tight Media Control

Namespace for Tight Media Control

application/media_control+xml

See RFCXXXX.

END 11. Security Considerations This document does not introduce new security considerations beyond covered in [4]. 12. Changes History 12.1. Changes since -04 This version defines only the picture fast update command since the rest of the commands are not use by shipping products. The document now states that RTCP feedback is to be used in new implementations. 12.2. Changes since -03 This version reflects the deployment experience since the defined mechanism has been implemented and tested among the vendors represented by the authors of this document. The XML schema is identical to version -03. 12.3. Changes since -02 This version contains editorial changes only. The XML schema is identical to version -02. Levin, et al. Expires July 18, 2007 [Page 9] Internet-Draft Media Control January 2007 13. References 13.1. Normative References [1] Levinson, E., "SGML Media Types", RFC 1874, December 1995. [2] Turletti, T., "RTP Payload Format for H.261 Video Streams", RFC 2032, October 1996. [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [4] Donovan, S., "The SIP INFO Method", RFC 2976, October 2000. [5] Murata, M., St. Laurent, S., and D. Kohn, "XML Media Types", RFC 3023, January 2001. [6] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A., Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP: Session Initiation Protocol", RFC 3261, June 2002. [7] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003. [8] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. [9] Wenger, S., "Codec Control Messages in the RTP Audio-Visual Profile with Feedback (AVPF)", draft-ietf-avt-avpf-ccm-03 (work in progress), December 2006. 13.2. Informative References [10] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, "Extended RTP Profile for Real-time Transport Control Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, July 2006. Levin, et al. Expires July 18, 2007 [Page 10] Internet-Draft Media Control January 2007 Authors' Addresses Orit Levin Microsoft Corporation One Microsoft Way Redmond, WA 98052 USA Email: oritl@microsoft.com Roni Even Polycom 94 Derech Em Hamoshavot Petach Tikva, 49130 Israel Email: roni.even@polycom.co.il Pierre Hagendorf RADVISION 24, Raul Wallenberg St. Tel-Aviv, 69719 Israel Email: pierre@radvision.com Levin, et al. Expires July 18, 2007 [Page 11] Internet-Draft Media Control January 2007 Full Copyright Statement Copyright (C) The Internet Society (2007). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Intellectual Property The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be found in BCP 78 and BCP 79. Copies of IPR disclosures made to the IETF Secretariat and any assurances of licenses to be made available, or the result of an attempt made to obtain a general license or permission for the use of such proprietary rights by implementers or users of this specification can be obtained from the IETF on-line IPR repository at http://www.ietf.org/ipr. The IETF invites any interested party to bring to its attention any copyrights, patents or patent applications, or other proprietary rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf-ipr@ietf.org. Acknowledgment Funding for the RFC Editor function is provided by the IETF Administrative Support Activity (IASA). Levin, et al. Expires July 18, 2007 [Page 12]