1. Multimedia Internet Broadcasting and Distributed Conferencing Lecture 2

2. Internet broadcasting and TV u Terrestrial and satellite TV –broadcasts to large audiences –has “economy of scale” –provides popular programmes and events u Internet broadcasting (IB) –allows small events to be broadcast –can reach small but global audience –provides low-cost, user-level broadcasting

3. What is out there? u Internet broadcasts (Audio and Audio/Video) are now common practice u Some are –well-designed –easily accessible –widely available u Others are difficult to access and view/hear

4. Access to IB u In general all users can access IB u shared links cause capacity shortfall u variable capacity broadcast u lowest quality at 28.8 kbps –small picture –low frame rate –low bandwidth audio u Home-based users need special attention

5. The home-based user u low bandwidth connection u shared links between Internet service providers (ISPs) limit bandwidth u IB allows home user to be active in “production” - not solely consume! u Quality of Service (QoS) is dependent on the provider - there are few user options

6. Software u Many now available –CuSeeMe/WhitePine Video conferencing –Real Networks – RealPlayer G2 –Microsoft Media Player –Quicktime u Either –two way communication (conferencing) –one-way communication (broadcasting)

7. Real Systems u rtsp or http –rtsp - real time streaming protocol (RFC 2326) –works over TCP or UDP (and could use RTP) –uses URL rtsp://host.domain/dir/file as in http –rtsp and request channel separate –(out-of band control) –port 554 is standard –Uses Real’s Surestream encoding

8. Surestream (RealPlayer G2) u Embeds a number of bit-rate versions in an encoding u Rates from 28.8 kbps up to corporate LAN capacities u Switches rate based on network congestion/capability –i.e. Adaptive/dynamic streaming of data

9. Servers u Broadcasting is generally done with servers u Servers (Reflectors in CUSeeMe) allow –a number of users to connect to a single source –links to other servers to reach v larger audience v geographically-dispersed audience

10. Infrastructure issues u Configuration of servers and inter- server links determines network QoS for individuals u Home-based users can choose server but a (network) local server usually performs best u For broadcasting to be an important tool the delivery infrastructure needs careful design.

11. Example events u Concert broadcast –Wolverhampton and Aberystwyth Universities joint venture (concert in Machynlleth, Wales) –used CUSeeMe with reflectors in –UK (3), France, US(2), and Australia u OECD Seminar - Turku, Finland –broadcast by EUNet –linked servers in various EU countries

12. Infrastructure models u Various models u Each has its own application area u Choice depends upon –QoS required –Audience –Network operator participation –other factors

13. Single server

14. ISP netcasting

15. Linked individual sites

16. Co-operation agreements

17. Working practices u Event-dependent –Video/Audio need to be useable –and should account for v small picture size v limited bandwidth v typical user terminal u New technical solutions may be needed u Higher bandwidth networks will help

18. Protocols u Current protocols are mainly not optimised for use in broadcast environments u Use of multicasting can help u Reservation protocols will improve QoS u Home-based users (in particular) are reliant on many outside factors to provide good QoS.

19. Multicasting u Depends on multicast routers (see RFC 1112) u Routers maintain multicast groups and deliver messages to individual hosts u Cuts down on duplication of messages except for low-use wide-spread connections u Multicasting is useful if audience is grouped

20. Reservation protocol - RSVP u RSVP (RFC 2205) u Uses control messages to reserve capacity along a TCP connection u Works with TCP/IP - IPv4 and v6 u RSVP provides transparent operation through routers that do not support it. u RSVP makes resource reservations for both unicast and many- to-many multicast applications, –adapting dynamically to changing group membership as well as to changing routes u RSVP is receiver-oriented, –i.e., the receiver of a data flow initiates and maintains the resource reservation used for that flow.

21. RSVP characteristics summary u RSVP is simplex, i.e., it makes reservations for unidirectional data flows. u RSVP maintains "soft" state in routers and hosts, providing graceful support for dynamic membership changes and automatic adaptation to routing changes. u RSVP is not a routing protocol but depends upon present and future routing protocols. u RSVP transports and maintains traffic control and policy control parameters that are opaque to RSVP. u RSVP provides several reservation models or "styles" to fit a variety of applications.

22. Future use u Higher bandwidth will help but –it will be more expensive –not available to all –inter-ISP links are also factors in QoS –infrastructure and configuration is still relevant u Wider use will use available bandwidth – so broadcasts need planning

23. Other areas u Computer supported co-operative work (CSCW) u Teleteaching u Video conferencing

24. Conferencing u Conferencing or two-way video/audio introduces new problems. u Many possible solutions u ISABEL architecture allows –Distributed conferences –Multi-point access for send and receive

25. ISABEL u A management platform –Scalable architecture covering large geographical areas and many sites –global event management from a single point –services can be defined and tuned –heterogeneous networks

26. Isabel service model Type of service, site, role etc Network configuration etc

27. ISABEL sites u 1. Interactive site –send and receive, audio, video and data u 2. Main Interactive site –An IS but with special privilege e.g bigger screen. (It may have a local audience) u 3. Control site –the most important site which controls the event u 4. Watch point –receive-only site

28. ISABEL layered architecture

29. Typical configuration

30. Summary u Different models of broadcast infrastructure have been proposed with different application areas u Home-based users rely on ISPs to provide QoS u New developments may not be the solution u Providers should develop infrastructures to support broadcasts to (and from) homes u Conferencing is a much more complex activity

31. References u Broadcasting –RSVP - RFC2205 (ietf web site) –Multicasting - RFC 1112 (ietf web site) –Sloane A (2000), “ Infrastructure issues for Internet broadcasting to home-based users”, in Beardon, Munari and Rasmussen (Eds.), “Computers and Networks in the Age of Globalisation”, Kluwer, Boston, ISBN0-7923-7253-0, pp187-196 u Conferencing –Robles et al “Distributed Global Conferences over heterogeneous networks” in Sloane A and Lawrence D (2001), Multimedia Internet Broadcasting, Springer, London Chapter 4