XCON BOF R. Even Internet-Draft Polycom Expires: December 21, 2003 O. Levin RADVISION N. Ismail Cisco Systems, Inc. June 22, 2003 Conferencing media policy requirements draft-even-xcon-media-policy-requirements- 00.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 December 21, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This document defines the requirements for Media Policy, i.e. a set of rules associated with the media distribution of the conference. This document presents the requirements for the media manipulations that can be done using these rules by conference participants or third parties using any kind of media/conference policy control protocol. This document does not address the interface between the focus and the media policy. Even, et al. Expires December 21, 2003 [Page 1] Internet-Draft media policy June 2003 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Rational . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 4. High Level Architecture . . . . . . . . . . . . . . . . . . . 3 5. Media Policy Data Model . . . . . . . . . . . . . . . . . . . 5 5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 6. Media Policy Requirements . . . . . . . . . . . . . . . . . . 6 6.1 Genera Media Policy Requirements . . . . . . . . . . . . . . . 6 6.2 Video specific requirements . . . . . . . . . . . . . . . . . 7 7. Security Considerations . . . . . . . . . . . . . . . . . . . 7 References . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . 9 Even, et al. Expires December 21, 2003 [Page 2] Internet-Draft media policy June 2003 1. Introduction The Conferencing Framework [2] presents an overall framework and defines the terminology for SIP [1] tightly coupled conferencing. The conferencing framework architecture includes the media policy. This is a set of rules that describes the media distribution of a conference. This document presents the requirements for the media policy data model and for the manipulations on these rules by conference participants or third parties using any kind of media/ conference policy control protocol. This document does not address the interface between the focus and the media policy and between the focus and the media mixer. 2. Rational The media policy enables a conference participant or an application server to define and manipulate the content of the media streams going to the conference participants. This will enable applications like sidebars, announcement to specific participants, call centers and panel conferences. 3. Terminology The draft relies on the terminology defined in the conferencing framework document[2]. 4. High Level Architecture The basic conferencing architecture used in this document is defined in the Conferencing architecture framework [2]. This document focuses on the media policy component and the requirements to manipulate the media policy by authorized entities. An authorized entity can manipulate the media policy using a supplied application. Examples for such applications include a web application, an interactive voice response application, an interactive Instant Messaging (IM) base application, or an application that uses the media policy control protocol. The Conference policy control protocol (CPCP) provides a standard way for an automated authorized entity to manipulate the media policy. The requirements and definition of the CPCP protocol are out of scope of this document. The media policy is a set of rules that describes the media mixing or switching required for each participant in the conference. This includes the set of sources to be mixed or switched and the rules for their mixing or switching. The focus uses the media policy to Even, et al. Expires December 21, 2003 [Page 3] Internet-Draft media policy June 2003 determine the proper configuration of the mixers. Authorized entities will be notified of changes to the media policy by subscribing to the conference event package. The information about the current contributing sources to the mixed streams can be learned by the information in the RTP header or by the conference event package [4]. The data structures that include the contributing sources of the current streams is in the focus or the mixer and is not in the scope of the work. The initial state of the media policy data structure is defined at the conference creation time. It can be either provisioned or created by using a conference policy control protocol or/and other protocols being used to create the conference. Typically, a focus has access to the media policy and is responsible for translating the media policy data into the actions towards the physical entities ("mixers"). Figure 1 describes an instance of media policy of a conference. The figure shows a single mixer and a single type of stream for ease of drawing but the model does not have such a restriction. Even, et al. Expires December 21, 2003 [Page 4] Internet-Draft media policy June 2003 Conference . Policy . +-----------+ //-----\\ . Control . | | || || . Protocol . | Conference| \\-----// . +------------->| Policy | | | . | . | Server |----> |Conference . | . | | | | . | . +-----------+ | & | . | . | | . | . | Media | . +------------+ . +-----------+ | Policy| . | +----------++ . | | \ // . | | || . | | \-----/ . |Participants||<-------->| Focus | | . | | || SIP . | | | . | | || Dialog . | |<-----------+ . +-+----------++ . +-----------+ . +-----------+ . | . ^ | . | . | | Contributing . | . | | Streams . +-----------+ . | +------------->. | | . | Distributed . | Mixer | . | Streams . | | . +-------------------. +-----------+ . ..................................... Conference Functions Figure 1: Media Policy in a Conference 5. Media Policy Data Model 5.1 General The fundamental conferencing functionality is being able to combine (i.e. "to mix") in a media specific manner participants' streams that belong to a logical sub-function within a conference (such as participant's video, left audio stream, right audio stream, video streaming presentation, slide presentation) and are of the same media type (such as video, audio, etc.). In the case of using centralized-mixing the resultant stream(s) will be sent back to the participants. In the case of end-point mixing, the original streams, needed to produce the mixed media, will be distributed to the participants that will perform the actual mixing. Even, et al. Expires December 21, 2003 [Page 5] Internet-Draft media policy June 2003 Typically, the maximum number of different mixers in a conference is preconfigured as part of the media conference policy. Mixers MAY be dynamically created and destroyed during the conference lifetime. This document will not describe the data model itself. 6. Media Policy Requirements All the requirements are based on having a privilege mechanism that authorizes users to access and manipulate the media policy data. The requirements are for the manipulations that can be done on the media distrbution by the mixer using the CPCP protocol. The protocol itself is not in the scope of this document. Authorization is also part of CPCP. The requirements are not for the mixer itself. 6.1 Genera Media Policy Requirements REQ-GP1: An authorized participant MUST be able to specify its own unique topology. REQ-GP2: It MUST be possible for a group of users to receive the same mix. This mix may be a conference common mix. REQ-GP3:It MUST be possible, using the protocol, to dynamically modify the number of contributing streams associated with a mixer. REQ-GP4: It MUST be possible, using the protocol, to define the mixing function for each participant in the conference. REQ-GP6: It SHOULD be possible to send a participant multiple streams from one mixer. This requirement is to enable support for end- point mixing. REQ-GP7: It SHOULD be possible to define relationships between different mixers. The relationships can be time synchronized such as specifying that the audio mixer and video mixer is a pair to establish lip-synchs. REQ-GP8: It SHOULD be possible to define the number of different topologies and the number of streams in each of them that will be mixed in a mixer. For example the conference will support only one video topology that will go to all the participants, the video topology will support 2x2 display, or each participant will be able to receive his own audio topology that will include up to 4 contributing sources. REQ-GP9: It SHOULD be possible to have more then one stream from the same type (video or audio) coming from the same user and to mix them separatly. For example one video stream will be the video camera Even, et al. Expires December 21, 2003 [Page 6] Internet-Draft media policy June 2003 showing the speakerwhile the other may be a presntation or a second camera showing the whole room. 6.2 Video specific requirements Video is a bit different than audio when mixing is concerned. In multipoint video the common mixing modes are: Video switching where one of the contributing sources is sent to all participants, the video source may be forced by the media policy control protocol or may be dynamic by using for example a voice activated video switching mode where the participants will see the loudest speaker. "Continuous presence" or tiled windows display where the topology is composing one video stream that has a layout defining the shape and position of viewing windows that will be displayed to the participants. The layout includes N viewing windows so that in each of the windows there is one contributing stream. Even though the viewing windows can be of any shape we will address in this work only rectangular windows of any size. The windows may overlap. The section defines the specific requirements for media policy and media policy control to enable "Continuous presence" REQ-V1: It should be possible to define rectangular overlapping windows in a video mix. REQ-V2: It should be possible to map a stream to a window based on some mode like having one window display the loudest speaker or the floor holder while for the remaining windows fixed input streams are used. REQ-V3: It should be possible for authorized participants to change the layout of the video topology. REQ-V4: It should be possible for authorized participants to define the mapping of a stream to a window. 7. Security Considerations The media policy control protocol may enables unauthorized users to manipulate the media mixing of conferences, this may enable them to listen to conference or eject unsolicited media streams. The protocol should provide authentication of the users. The media policy data may include information about the sources and targets of mixer, if this information will be transferred in the protocol in the clear that may cause a security risk. The protocol should allow for Even, et al. Expires December 21, 2003 [Page 7] Internet-Draft media policy June 2003 encryption of the media policy transferred in the media policy control protocol. References [1] 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. [2] Rosenberg, J., "A Framework for Conferencing with the Session Initiation Protocol", draft- rosenberg-sipping-conferencing-framework-01 (work in progress), February 2003. [3] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model with Session Description Protocol (SDP)", RFC 3264, June 2002. [4] Rosenberg, J. and H. Schulzrinne, "A session initiation protocol (SIP) event package for conference state", , June 2002. Authors' Addresses Roni Even Polycom 94 Derech Em Hamoshavot Petach Tikva 49130 Israel EMail: roni.even@polycom.co.il Orit Levin RADVISION 266 Harristown Road Glen Rock NJ USA EMail: orit@radvision.com Nermeen Ismail Cisco Systems, Inc. 170 West Tasman Drive San Jose 95134 CA USA EMail: nismail@cisco.com Even, et al. 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Expires December 21, 2003 [Page 9] Internet-Draft media policy June 2003 HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Acknowledgement Funding for the RFC Editor function is currently provided by the Internet Society. Even, et al. Expires December 21, 2003 [Page 10]