ukerna mbone itu 961209 ptk

Mbone Multimedia Conferencing : 

Mbone Multimedia Conferencing Peter Kirstein University College London Comparison with ITU-T Activity

Scope of this presentation: 

Scope of this presentation My definition of multimedia conferencing Emerging trends in multimedia conferencing Current activities in ITU-T and Mbone The integration under the MERCI Project Conclusions

Essential Conference Features: 

Essential Conference Features Several real users involved together Several media - e.g. Video, Audio and Shared data - with external sources The components should be interactive even if used mainly in one-way mode We consider here only WAN application We want both desk-top and Conference rooms

Desirable Conference Features: 

Desirable Conference Features Support for Conference Rooms & Workstation Facilities for recording, adding slides, film clips etc Shared workspace support matched to applications Ability to work over several communications nets During the same conference Ability to support difference classes of user Network, workstation power, network bandwidth Ability to have confidential conferences Ability to announce, manage & control conferences

Conferencing Standards: 

Conferencing Standards Approaches are proprietary or Standard If Standard, there are still many choices Here we consider only a Standard approach Areas where standards are needed: Network, multiplexing and transport Media coding Conference control Conference invitation and announcement Security - both of contents and existence

Timeliness of the Technology: 

Timeliness of the Technology Digitisation of computers and communications Emergence of ubiquitous powerful workstations Most W/S have some facilities for MM Standard audio and video compression can be implemented in S/W or H/W - on W/S and PCs Most commercials can access LAN and WANs Processing and storage have become affordable

Typical Multimedia W/S: 

Typical Multimedia W/S SPEAKER MIKE

Multimedia Workstations: 

Multimedia Workstations Standard Workstation Audio Speaker, Microphone, possibly hardware audio Codec Camera, framestore, possibly projection device, hardware video codec Communications I/O

Schematic of Conference Room: 

Schematic of Conference Room SPEAKER MIKE CAMERAS AUDIO MIXER/ SWITCHER VIDEO MIXER/ SWITCHER M U L T I P L E X O R

Typical Conference Room: 

Typical Conference Room Workstation/ Digital Control Audio Speakers, Microphones, possibly hardware audio Codec Cameras, framestore, projection device, usually hardware video codec Communications I/O - often multi-channel Audio and Video mixers and switchers

Main CR/WS Differences: 

Main CR/WS Differences CR has more and better audio/video peripherals CR often has Hardware codecs, WS software CR has more emphasis on flexible mixing, switching and echo cancelling In CR, the mixing and switching is often done in electronics which attach directly to the comms In CR, the workstation I/O is often attached to the mixing/switching/multiplexing/coms I/O

The sets of Standards: 

The sets of Standards There are many proprietary solutions Several sets of relevant Standard prevalent ITU-T and Mbone application level Standards Most ITU stream-based, Mbone packet-based comms Internet, ATM, ISDN etc at network level Many different standards for the media Video & audio coding, shared workspace, MM server Different Conference model impacts standards

ITU-T Conference Architecture: 

ITU-T Conference Architecture ITU-T Model is Transmitter based ITU-T communications often stream based Tightly Controlled conferences normally having only a few participants - <10 Participants have largely the same level of facilities - communications and W/S Out-of-band Announcement and Invitation Multi-user achieved in central hubs

Mbone Architecture: 

Mbone Architecture Heavily dependent on IP properties Communications packet-based; relies on IP multicast, though over different network technologies Receivers decide to join - and network adjusts Receivers may have widely different capability Number of receivers potentially very large All the management activities should be in-band Media streams can follow different paths

ITU-T Topology: 

ITU-T Topology COM NET COM NET MCU

Schematic of Mbone: 

Schematic of Mbone R R

Some ITU-T Standards: 

Some ITU-T Standards Network features (e.g. pcm, ATM etc) Frame structure, frame control, transport Audio and video codecs General conference control of multiple-point control units Shared whiteboard procedures Security Encryption of streams, key management

Some Mbone Standards: 

Some Mbone Standards All network and routing aspects identical to the Internet procedures Data forwarding, control, announcement heavily dependent on IP multicast Most media compression standards from other standardisation bodies Standardisation of transport, session control, session announcement and invitation Security in media streams and announcement

Advantages of ITU-T Systems: 

Advantages of ITU-T Systems Large take-up by industry Many specialised chips Complete packaged systems Good support for ISDN and other normal systems, some support for other networks Quality depends mainly on bandwidth and compression - independent of network load- provided that there is dedicated B/w

Problems with ITU-T Systems: 

Problems with ITU-T Systems Do not work between different powers of workstations and network Due to nature of multiplexing and network support Do not scale well to large numbers of participants Because of MCU philosophy, and tight control Cannot easily modify specific media streams to traverse network poor regions - again multiplexing Multi-point operation normally centralised Systems normally closed and not extensible - They work poorly with VBR traffic

Advantages of Mbone Systems: 

Advantages of Mbone Systems Can use whatever Internet access or backbone system is available Multicast scales to very large numbers of participants Multi-point operation is distributed Copes well with using different network parameters for different media types Works well between users with different levels of workstation, network and media

Disadvantages of Mbone Systems: 

Disadvantages of Mbone Systems Difficult to get guaranteed Quality of Service though RSVP is changing this Requires careful Mbone traffic engineering Newer facilities not yet fully proven: hierarchichal coding, key distribution, transcoding gateways Still needs better applications management facilities

Requirements of both systems: 

Requirements of both systems Devices to connect C/R , W/S to WAN Facilities for stream management, multiplexing, and code translation - if heterogeneous systems Conference management and control - including set-up and booking - is standardised for Mbone Mechanisms for securing applications - not yet standardised for ITU-T Suitable A/V peripherals and communications

Quality Differences ITU-Mbone: 

Quality Differences ITU-Mbone It is difficult to draw too many conclusions just from the Standards; implementations matter ITU-T has muxed streams; thus a single A/V stream takes a little less B/W than Mbone Because ITU-T has muxed streams, it is not normal to have differential QoS in conferences ITU-T systems support a smaller range of audio and video codings than Mbone - none hierarchic

Comparison of Current Systems: 

Comparison of Current Systems ITU-T ones could have flexible computer control like Mbone ones - most have not Current ITU-T systems are much more inflexible in support of shared workspace than Mbone Current ITU-T systems do not support transcoding relays, MMservers, or varieties of network Current ITU-T have a better integrated and well-designed man-machine interface

Other comparisons: 

Other comparisons With audio mixing and video packet filtering, relays, Mbone conferences can support participants with widely varying facilities Using separate VPs on ATM portions, and RSVP on other IP portions, Mbone can multiplex communications much more efficiently than ITU-T

New Network Developments: 

New Network Developments Internet with multi-cast available - in US and Internationally - to T1 or T3 Early Generation of Multicast Routers limited to 500 Kbps - to protect network Current M/c routers can go much faster - and can incorporate RSVP routing Mbone is operational currently at speeds from 64 Kbps to about 20 Mbps - the quality depends on bandwidth used

Server Requirements: 

Server Requirements Record multipoint conferences Source should be any conferee Single Point of Contact for Record/Play Playback recorded material Directly to user or into Multicast conference Synchronise between streams Allow user creation of segments of recorded material, indexes, annotation

Server Developments: 

Server Developments Video on Demand provides many of the required facilities Indexing and retrieval usually inadequate Standard Transport protocols usually different There is often problem in remote control There may be problems in recording multiple streams

Specific Example - MERCI: 

Specific Example - MERCI Uses existing tools & networks available Use any available networks: Internet n x 64 Kbps ISDN, SMDS and ATM Emphasis though on Mbone multicast Use International Standards for key components - they must interwork Must have collaboration both with European and US user sites Prefer to adapt tools than to develop

MERCI Objectives: 

MERCI Objectives to provide improved tools which run on Workstations & PCs interwork Internet & ITU-T standards with Security and Server storage facilities ensure operations on a variety of networks provide both high and medium quality on workstations and conference rooms for applications in conferencing, teaching surgery, industry

Basic Outside Tools Adopted: 

Basic Outside Tools Adopted Packet Voice - with redundant coding Packet Video - supporting H.261, MPEG and hierarchical coding Several Shared Workspace tools Shared whiteboard, editor or visualisation Conference announcement and invitation Video Server to allow recording and introduction of material Ability to encrypt streams and announcements

Application Workpackages: 

Application Workpackages Seminars Surgical Workshop Industrial trials Usability and Evaluation

Current State of System: 

Current State of System All tools work on many Unix Machines, PCs under Windows’95 - and many under NT Few ITU tools work under Unix, and on systems other than PCs Interworking gateways between ITU-T and Mbone will be delivered early in 1997 Secure conferencing tools and announcement OK Early versions of MM Server operational Systems work over ATM, Internet and ISDN Audio mixing and video filtering nearly ready

Interworking Approach: 

Interworking Approach Provide gateway between Mbone / ITU terminals Main problem: different conferencing paradigms (loosely-coupled, tightly coupled) First approach: provide Mbone terminals with additional tool (Session Controller) which allows them to enter ITU-conferences based on IETF protocols: SIP, SCCP SC distributed in same fashion as Mbone tools Two GWs: Mbone/H.323 GW, H.323/H.320 GW

Network Activity: 

Network Activity Set up Mbone Infrastructure via JAMES & National Networks - though little SuperJANET yet Linking in ordinary Mbone feeds - avoiding flooding of slower portions Setting up national ISDN gateways - with audio mixing and video switching Investigating use of Resource Reservation Could not use UK CRs - not properly equiped

MERCI Mbone Topology: 

KTH SE OSLO NO ICM US UCL UK STOK EBON DARM DE RUS DE US CAIRN US JAMES 2 Mbps INRIA FR MERCI Mbone Topology CRC CA ISDN ISDN ISDN UKERNA UK ULB BE UNI-C DEN INFN IT LINZ U AT DELFT NE 34/155 MBPS James National Currently working

Multimedia Record/Playback: 

Archive VCR Server M/C for data M/C for Ses Mes Multimedia Record/Playback VCR Client

Conference control: 

Conference control Booking & set up - SDR (SDP, SAP, SIP) Used also for MM Server, Mixer, Key distrib Active Conference Control - SCCP Conference relays - ITU - Interworking Probably needs extra module in WS Conference relays - ISDN Needs audio mixing, and video switching Transcoding Relays Needed between tools, ITU-Mbone, use by wavelet relays etc

Security Support: 

Security Support Most tools secured - export problem Use DES for media, RSA for key distribution Interested only in end-to-end security Authentication of participants - for use of SIP Encryption gateways - between ITU and Mbone Using ICE-TEL infrastructure and tools where a security infrastrucure is required

Conclusions: 

Conclusions Several complete systems for conferencing exist The Mbone and ITU-T have different strengths Commercial pressures provide improvements in the different systems separately To capitalise on individual improvements, and to reuse investments integration of Mbone and ITU tools vital Integration of media tools with announcement and security management is vital for simple usage most tools are so designed, not all yet so integrated Network, WS & performance heterogeneity vital

The Immediate Future: 

The Immediate Future Hardware and software are still improving rapidly; tying into H/w solutions is dangerous Flexibility and Usability are now vital targets in MERCI - they should also be in UKERNA plans To capitalise on past investments in peripherals, all MM studios should be equiped with M/c routers and reasonably powerful W/Ss That Mbone tools are only for WSs is a myth they can easily out perform ITU ones on quality

Medium Term Activity: 

Medium Term Activity In the medium term, one should support layered encoding to allow heterogenous activity ISDN gateways, audio mixing, packet filtering, audio and video transcoding remain important to accommodate disadvantaged participants More ambitious linkages - like to Cable TV and DBS sites - is not far away ITU - Mbone gateways remain a requirement

Conclusions: 

Conclusions The past activity of UKERNA should have considered Mbone technology also for CRs With the future emphasis on both CRs and WSs, it is essential that the newer technologies be evaluated also, and used where appropriate The main investment is in rooms and peripherals, it is vital that their productity be maximised The immediate future is exciting, but systems thinking, and input from users, remain essential