EBU Technical Review : No. 282 (March 2000)
`
`Webcasting
`
`– the broadcasters’ perspective
`
`F. Kozamernik
`EBU Technical Department
`
`This article is based on the work carried out by the former EBU Webcasting
`Group [1]. It provides an update on the extremely fast developments in the
`area of webcasting that have occurred since the publication of the Group’s
`document, “BPN 022 – Practical Webcasting”. It also outlines some of the
`opportunities and challenges provided by webcasting and gives some
`indication of the future prospects.
`
`In particular, the article explores the impact of the Internet on the
`broadcasting sector. We are witnessing the process of convergence
`between the Internet and the emerging digital terrestrial and satellite
`broadcast systems. The convergence of the PC and digital broadcast
`terminals is bringing about the delivery of new services as part of the
`multi-channel offerings from digital radio and television broadcasters.
`
`1.
`
`Introduction
`
`The World Wide Web (WWW or Web) is the multimedia dimension of the Internet and
`allows audio-visual material to be accessed using a standard web browser. In recent
`years, many radio and television broadcasters have created websites and have established
`themselves on the Internet. In parallel, as radio and television chains are being digitized,
`these new infrastructures are being used to carry web content at high speed to DAB and
`DVB receivers. For the broadcasters, web technology is becoming an interesting tool to
`produce, contribute, distribute and broadcast radio and television programmes.
`
`Since the beginning of the 90s, EBU members have been introducing new digital tech-
`nologies in their studio production facilities, and developing new digital transmission
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`1 / 28
`
`PAGE 1 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`technologies for DAB, DVB and, more recently, Digital Radio Mondiale (DRM). Con-
`ventional broadcasting – using traditional delivery mechanisms (satellite, cable and ter-
`restrial networks) – reaches hundreds of millions of people, and provides nearly
`complete country-wide coverage: furthermore, the technical quality of the audio and
`video signals, as received at home and on the move, is largely seen to be satisfactory.
`Radio and TV receivers are widely available and are relatively non-expensive.
`
`WEBCASTING
`
`Abbreviations
`
`64-QAM 64-state quadrature amplitude
`modulation
`
`ADSL
`
`Asynchronous digital subscriber line
`
`ISP
`
`Internet service provider
`
`MPEG Moving Picture Experts Group
`
`MVDS Multipoint video distribution system
`
`Application programming interface
`
`(Microsoft) Advanced Streaming
`Format
`
`PDF
`
`PNG
`
`(Adobe) portable document format
`
`Portable network graphics
`
`API
`
`ASF
`
`CSS
`
`DAB
`
`DRM
`
`DSL
`
`Cascaded style sheets
`
`Digital Audio Broadcasting
`
`Digital Radio Mondiale
`
`Digital subscriber line
`
`PSTN
`
`Public switched telephone network
`
`RRMP
`
`Restricted reliable multicast
`protocol
`
`RTCP
`
`Real-time control protocol
`
`RTP
`
`RTSP
`
`SIP
`
`Real-time protocol
`
`Real-time streaming protocol
`
`Session initiation protocol
`
`SMATV Satellite master antenna TV
`
`SVG
`
`TCP
`
`TDC
`
`UDP
`
`URL
`
`USB
`
`W3C
`
`WAP
`
`Scalable vector graphics
`
`Transmission control protocol
`
`(DAB) transparent data channel
`
`User datagram protocol
`
`Uniform resource locator
`
`Universal serial bus
`
`World Wide Web Consortium
`
`Wireless application protocol
`
`DSM-CC Digital storage media – command
`and control
`
`DVB
`
`Digital Video Broadcasting
`
`DVB-C DVB - Cable
`
`DVB-S
`
`DVB - Satellite
`
`DVB-SI DVB - Service Information
`
`DVB-T
`
`DVB - Terrestrial
`
`FTP
`
`File transfer protocol
`
`HTML
`
`Hypertext markup language
`
`HTTP
`
`Hypertext transfer protocol
`
`Institute of Electrical and Electronics
`Engineers (USA)
`
`IEEE
`
`IETF
`
`IP
`
`Internet Engineering Task Force
`
`WML Wireless markup language
`
`Internet protocol
`
`WWW World Wide Web
`
`ISDN
`
`Integrated services digital network
`
`XML
`
`Extensible markup language
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`2 / 28
`
`PAGE 2 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`The Internet, on the other hand, is a very convenient and successful means for sending e-
`mails, and for e-commerce, e-banking and other forms of electronic communication.
`However, at the present time, it is a very poor mechanism for carrying audio and, in par-
`ticular, video broadcast signals. It is far from being able to offer the high quality of
`reception that the new digital broadcasting systems readily provide. Compared to rela-
`tively cheap radio and television receivers, the Internet requires more expensive PCs and
`– of great significance – only several hundred (or thousand) computer receivers can be
`on-line at any given moment, depending on the capacity of the web server. And, as the
`use of the Internet for broadcasting is not very cheap either, it is not surprising that it is
`being considered by many broadcasters as purely a secondary medium.
`
`So why bother with such a “poor” delivery medium at all?
`
`Not only does the Internet have an enormous potential for quality improvement, but it
`also seems to have two important and far-reaching features that conventional broadcast
`systems seem to lack:
`
` it is inherently “global”;
`
` it is truly “interactive”.
`
`The term “global” means that any computer connected to the Internet is able to commu-
`nicate to any other computer. The Internet is a de facto worldwide network: national bor-
`ders present no obstacles when accessing it. In other words, a listener can select not just
`tens, but thousands and thousands of new radio stations from all over the world, in all
`possible languages.
`
`The term “interactive” means that any user can receive information from, and send it to,
`anybody else. This feature opens the door to a host of new broadcast applications and
`expands the very notion of broadcasting. The Internet may in principle allow any indi-
`vidual, or a group of people, to become a publisher or a “content provider”. The Internet
`may effectively blur the difference between the big and the small, the poor and the rich.
`It may even bring all broadcasters onto an equal footing. Since the geographical location
`of the Internet-user has become irrelevant, and the time of access is becoming less
`important, this may lead to a cultural and linguistic blend.
`
`It is beyond any doubt that the Internet will have a dramatic impact on all future broad-
`casting activities. Therefore, it is vital for broadcasters to become aware of, and to
`understand, all the technological, legal, social, economic, cultural and commercial con-
`sequences that the Internet brings with it.
`
`This article looks mainly at the technology-related aspects of webcasting. Other aspects –
`such as legal, regulatory, sociological and commercial – are, of course, equally important
`and even vital for the success of on-line services, but are not the subject of this article.
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`3 / 28
`
`PAGE 3 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`2. The WWW phenomenon
`
`In order to understand how important the Internet is for broadcasters, it may be useful to
`describe it in some detail. The Internet may be characterized as a physical information
`network that logically connects together millions of computers by using a globally
`unique address space, based on the TCP/IP suite of protocols. The Internet has no single
`control centre, nor a hierarchical structure. It allows the connection of any kind of com-
`puters (PC, Mac, UNIX, etc) and is a global phenomenon.
`
`The World Wide Web was first conceived in 1989 by Tim Berners-Lee as a project to
`improve collaboration at CERN (the European Laboratory for Particle Physics in
`Geneva) [2]. It was devised as a seamless model in which all the information on the
`Internet could be accessed in a simple and consistent manner – from any computer, in
`any country, by any authorized user. Anyone with a computer and the appropriate
`“extras” could connect to it, become part of the Web and use it to send and receive infor-
`mation in a variety of forms, with an easy-to-use interface.
`
`Although the Web soon spread outside the CERN labs, it did not take off until late 1992.
`Its sudden success was due to the popularity of Mosaic, a graphical browser created by
`NCSA (National Centre for Supercomputing Applications). Mosaic later evolved into
`Netscape Navigator/Communicator. Today, the Web is the most popular and fastest
`growing information system deployed on the Internet.
`
`The Internet offers many diverse resources, such as:
` e-mail, including the sending and receiving of attached files;
` Usenet (a vast system of discussion groups);
` Gopher (menu-based information) with the Veronica search engine;
` FTP (file transfer protocol) with the Archie search engine;
` Telnet (for connecting to and using a remote host);
` “Newsgroups” (where people can communicate on any subject);
` “Chat” programmes (which let people communicate with others in real-time –
`much like a written phonecall);
` E-commerce (which enables people to purchase books, software, CDs, travel tick-
`ets, etc.);
` On-line newspapers;
` Music downloads;
` Interactive games;
` Real-time radio (and even television) stations;
` Video teleconferencing;
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`4 / 28
`
`PAGE 4 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
` Long-distance telephony.
`
`Over 80% of all Internet traffic now comprises applications based on HTTP, which
`allows navigators (browsers) to move easily from one document to another, via hyper-
`links. Web pages – containing text, graphics, sounds, animations, audio, video and links
`to other web pages – can be created using HTML and these pages are referred to as HTM
`files.
`
`HTML is a set of tags – i.e. text enclosed by the “lesser-than” (<) and “greater-than” (>)
`symbols – which identify the structure of the document. The essential characteristic of
`the Web is its hyperlinks. To the user, a hyperlink is either text (usually signified by
`being underlined and in a colour different from other text) or a graphic image that you
`can click on with your mouse to access the target resource (usually another document).
`The target resource can either be on your hard-drive or anywhere else in the world that is
`connected to the Internet. The address of a resource on the Internet (i.e. an Internet site)
`is given by its URL.
`
`The Internet is spreading like wildfire. One striking illustration of how quickly the Inter-
`net is evolving, is the time it has taken for various communication technologies to reach
`a threshold level of 50 million users. While it took around 75 years for the telephone, 38
`years for radio, 16 years for the PC and 13 years for TV to reach 50 million people, it is
`estimated that the WWW reached the 50 million mark in less than four years. In Sep-
`tember 1999, the Web achieved more than 50% penetration in five major American cities
`[3].
`
`Another development that reflects the booming growth of the Internet market is the
`number of ISPs. In the world of telephony, where monopolies have dominated the sector
`for several decades, the opening of the market has lead to a rapid growth in the number
`of service providers. The number of international telephony carriers worldwide has
`grown from less than five hundred in 1996 to more than a thousand in 1998. However,
`these figures are dwarfed by the growth in ISPs; some estimates suggest that more than
`twenty thousand ISPs are operating presently around the globe.
`
`3. Webcasting
`
`The Internet provides for some radically new models for delivering broadcast content,
`including audio and video programmes, to the end users. Webcasting is the term used to
`indicate the production, transmission and delivery of hyperlinked documents consisting
`of text, audio and visuals (i.e. video and graphics) – for presentation via a browser-like
`interface. Contrary to conventional broadcasting which is one-way only, webcasting
`allows the audience to interact with the originator, and to shape what is delivered. The
`simplest form of webcasting involves streaming media (audio, video and text) where the
`production centre determines the context. A more complex webcasting form is audio-
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`5 / 28
`
`PAGE 5 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`on-demand or video-on-demand whereby the consumer determines the context and depth
`of what is delivered.
`
`Technically, streaming is a relatively new technology. In the early phases of the Internet,
`the entire audio and video files had to be downloaded to a customer’s hard-drive before
`they could be played out by the client’s player. Therefore, the user had to wait until the
`whole file had been downloaded successfully to his/her computer. The downloading
`method is still used extensively for music delivery, if quality is an important require-
`ment. For instance, the downloading of a compressed audio bitstream at 128 kbit/s (e.g.
`in the MP3 format) would require a hard-disk space of slightly less than 1 Mbyte per
`minute of audio duration. The downloading time will depend on the “bandwidth” of the
`Internet channel and on the actual modem connection speed. Assuming a 28.8 kbit/s
`modem, the net bit-rate will be about 20 kbit/s. Thus a musical clip of three minutes
`duration would be downloaded in about 20 minutes.
`
`It can be deduced that the “download-first-and-then-play” technology can be suitable for
`short programme clips, but not for on-line radio listening or even for watching video
`clips. The streaming technology, on the other hand, allows for immediate playback.
`Modern players, such as for example RealPlayer ™, are able to read the file stream as it
`is coming in, and can begin playing it before the rest of the file has arrived. In order to
`make the playback smooth, the player uses a process of buffering. During buffering, a
`number of the streaming packets are collected before playing them out. As the player
`begins to play out the file, it continues to collect packets in reserve. If there are minor
`delays in receiving the packets, playback will still be continuous.
`
`4. Some statistics
`
`Around 220 million people worldwide now have access to the Internet and the number of
`on-line connections is growing steadily by about 100 000 a day. The question to be
`asked is how this growth is affecting the broadcasters and whether or not television may
`be loosing its eyeballs!
`
`A recent study by Arbitron NewMedia [4] – about consumer media behaviour and new
`media preferences in the USA – showed that the Web is often used in conjunction with
`radio and television, and that the Web does not significantly lower the levels of TV view-
`ing. The heaviest web users are also avid consumers of traditional media. The study
`found that, during the peak hour for web use at work (9 – 10 a.m.), 26% of heavy web
`users reported that they listened to Internet radio. During the peak hour for both web and
`TV use at home (8 – 9 p.m.), 52% of heavy web users reported that they also watch tele-
`vision during this period, only slightly lower than that of all web users (55%). This
`points to the possibility of some innovative cross-media promotion and synergy, and the
`complementarity of programming. Thus, the traditional media should continue to extend
`their brands and franchises into cyberspace.
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`6 / 28
`
`PAGE 6 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`The Internet radio audience in the USA has doubled in the last half year. The above-
`mentioned study (made in January 1999) found that about 31 million people, or 13% of
`the US population, have listened to Internet radio, compared with only 6% in an earlier
`study. Increases in modem speeds at home, and Internet connections at work, have
`meant that Internet radio now sounds better. Also, there are more sound cards installed
`in PCs at the workplace.
`
`A study conducted by NPD in conjunction with the on-line newsletter, Iconocast, found
`that 57% of US users have the ability to use their TV and their PCs at the same time. Of
`those who “multitask”, 86% actually watch TV and surf the Internet simultaneously.
`According to the authors of the report, these results suggest that the TV and the PC will
`not converge. Among those who multitask, 91% said that they had visited a site on-line
`after being exposed to television advertising. The study also found that 75% of multi-
`taskers go on-line during TV commercial breaks. 20% of users said that they visited the
`site of a TV programme while watching the programme. Users were far more likely to
`respond to URLs advertised in commercials.
`
`As the Internet has become the all-purpose medium to deliver both business and pleas-
`ure, it is already possible to tune to very many radio stations. However, it should be
`stressed that, since the Internet is a huge and complex entity with many random varia-
`bles, it is not easy for its performance to be guaranteed. It is generally beyond the con-
`trol and the responsibility of the broadcaster to ensure a certain minimum quality of the
`signal received. In its report of March 99, Edison Research [5] stated that user-aware-
`ness of Internet radio in the USA was growing rapidly: at the beginning of 1998, only
`8% of users were aware of it, by the end of 1998 this figure had grown to 18% and, by
`March 1999, it had reached 27%. As the awareness of Internet radio grows, the number
`of people listening to it is growing as well. In parallel to this, the number of audio web-
`casters is also growing.
`
`The following statistics about audio webcasting are quite impressive (status: September
`1999 – source: BRSMedia.com):
` 6800 radio stations on the Web;
` 2616 radio stations worldwide with continuous audio streaming (in 1998: 1652 );
` 1296 radio stations in the USA and Canada;
` 1071 international radio stations;
` 196 internet-only radio stations;
` 52 radio networks.
`
`There are over two hundred live streaming television stations. Last July (1999), the
`broadcast.com website transmitted 410 live continuous radio, and 49 TV channels, as
`well as on-demand music from its CD Jukebox with 3000 titles. The number of new
`web-streamed channels and networks entering the arena is huge and it is now almost
`impossible to provide up-to-the-minute figures.
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`7 / 28
`
`PAGE 7 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`5. Opportunities for broadcasters
`
`It is evident that more and more broadcasters around the world are re-routing some por-
`tion of their programming output to the Internet. As the medium becomes more widely
`accepted and as new sources of advertising revenue are sought, an increasing number of
`broadcasters are drawing up plans to extend the reach of their signals to embrace the
`Internet.
`
`By using their websites, broadcasters could possibly attract more listeners/viewers than
`they can do through their conventional over-air radio and television services. They could
`possibly extend their audience base and thus generate more income streams from sub-
`scriptions. The Web could be used to achieve the following:
`
`Improved marketing communication: Provide the web viewers and listeners (some-
`times called viewsers) with some additional information about the broadcasting com-
`pany, its people, its strategies, its successes and its challenges.
`
`Greater information on programmes: Such information could include details about
`the past, current and future programmes, it could offer supplementary information about
`the actors, producers, etc. and could publish interviews with them. Conventional pro-
`grammes could be augmented with a package of text-based statistics, pictures and video
`clips of sports stars, etc.
`
`Improved customer contact: Communication through the Web could enable the contact
`with each customer to be more personal. Broadcasters could gather information about
`their customers and build up a long-term fidelity relationship with them. They could
`learn how large their market is and the size of their audience at any given time, by meas-
`uring the number of hits. In the case of commercial broadcasters, such information
`would help to attract additional targeted advertising.
`
`Increased merchandising of content: Broadcasters could make their extensive libraries
`and archives of content available for people to visit, consult, pre-view and pre-listen, and
`eventually to buy (download) the chosen content. However, watermarking and digital
`signature technologies must be developed and implemented first.
`
`All this aside, public service broadcasters might see the Web as (i) a natural extension of
`their current public service activities and (ii) an excellent mechanism for promoting their
`well-established brand.
`
`Many broadcasters are using the Web as an additional broadcasting outlet. Some stations
`have initially opted for a 90/10 approach, whereby 90% of their programming is broad-
`cast by conventional means and 10% is webcast on the Internet. This approach has
`recently been changed by some broadcasters more towards the 50/50 approach. These
`broadcasters have already realized the Internet’s potential for a wider audience and new
`revenue sources. Many broadcasters have now realized that major changes in station
`workflow are required; for example, creating separate Internet departments with stand-
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`8 / 28
`
`PAGE 8 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`alone hardware and specialized technical support. Others have realized that both con-
`ventional and Internet activities can exist side by side, using a common integrated pro-
`duction base.
`
`A new company, Omneon Video Networks [6] has recently introduced its Video Area
`Network (VAN), based on an IEEE 1394 architecture. It consists of five building blocks:
` a high-capacity storage disk array;
` a “Director” to control disks and manage files;
` multi-format codecs;
` an intelligent packet-switch for routing IEEE 1394 streams and for transmitting
`low bit-rate streams;
` a network Manager.
`
`The VAN is an integrated system, which provides a full range of conventional and Inter-
`net capabilities. High bit-rate streams are routed to conventional transmission pathways
`and the low bit-rate streams are routed to the Internet (via the packet-switch). Using the
`gigabit Ethernet port, the Internet stream is pushed to an ISP or web-hosting facility for
`splitting and distribution. Two independent commercial play-lists may be configured,
`one for conventional and one for Internet audiences. Using this integrated approach, a
`station’s news and production departments benefit from shared storage, production and
`archiving facilities, and shared management control. The overall workflow is stream-
`lined because the physical movement of media from department to department is elimi-
`nated.
`
`Traditionally, to a great extent, international radio broadcasting has been the role of gov-
`ernment-sponsored international broadcasters, using short-wave transmissions. But,
`gradually, more and more people are now tuning to Internet radio for listening to the
`services in their mother tongue, or a local radio station located perhaps on another conti-
`nent. In the case of some radio stations – such as RTE Ireland, Swiss Radio Internation-
`ale or Radio France Internationale – there is a limited (or no) short-wave alternative.
`
`The Internet also represents an opportunity for integrating the Web with television. Web
`content may be used to augment the existing analogue and digital television broadcasts;
`for example, programme-associated special offers, programme guides and reviews,
`background information on sports teams etc. Television displays could also be used to
`present web-type pages on such topics as news, weather, stock exchange and other infor-
`mation – not specifically linked to a particular programme. People expect television to
`work reliably, leading to a great emphasis on a universal approach and a correct imple-
`mentation of web standards in this area.
`
`It should be pointed out that, although the traditional broadcasters have been relatively
`quick to adapt to the Internet environment, they have not yet been able to gain the lion’s
`share of traffic and advertising revenue on-line. Instead, new Internet media companies
`– such as AOL, Yahoo, Excite, Lycos and Infoseek – have created so-called “portal sites”
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`9 / 28
`
`PAGE 9 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`and have gained the lead in stimulating traffic and advertising revenues. The power of
`portals, however, has not gone unnoticed by the big media players who have been active
`in acquiring stakes in major portal companies. For example, Disney took a 43% stake in
`Infoseek, and Bertelsmann has put some 10 million US$ into a partnership with Lycos to
`create portals in all the main European markets.
`
`A portal commonly refers to the starting point, or the gateway, through which users nav-
`igate the Web. However, the term “portal” is an evolving concept, as new functionalities
`are constantly added. Portals are projected to take an important market share in the
`future; they may acquire 20% of on-line traffic and 30% of on-line advertising revenue
`by 2003. There are two main types of portals: horizontal and vertical. A horizontal por-
`tal is a website that provides a wide range of services, such as e-mail, forums, search
`engines and shopping malls, and is geared to the mass audience (examples: Yahoo and
`AOL). A vertical portal (sometimes referred to as a “vortal”) focuses on a specific con-
`tent area and targets a particular niche audience.
`
`6. Basic webcasting technologies
`
`In order to perform webcasting, original broadcast programmes should be transformed
`into an Internet-ready audio-visual stream. This is not a simple process and involves
`several important programming and technology-related steps, as shown in Panel 1.
`
`The “push” method of delivery is real-time broadcasting, whereby the video/audio pro-
`gramme feeds are simultaneously pushed out to the Internet users, in much the same way
`that we broadcast our conventional terrestrial, cable or satellite feeds. This method is
`used successfully by several web broadcasters, such as CNN, the BBC and MTV.
`
`Panel 1
`Basic webcasting technologies
`
`Capturing: This process involves selecting the programme to be webcast. The programme
`could be an original Internet production or an adaptation of existing radio and television pro-
`grammes for the Web, or a combination of the two.
`
`Editing: This step involves editing the captured programme so that the presentation which
`the consumer receives is what the content provider intended. This step uses web-publishing
`and authoring tools.
`
`Encoding: This step implies the use of an appropriate compression scheme and a streaming
`technology to covert the programme into a file that can be streamed over the Internet.
`
`Delivery: The encoded file must then be placed on a special streaming server, and can be
`pushed to, or pulled by, the user.
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`10 / 28
`
`PAGE 10 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`The “pull” method is the transmission of hosted audio/video clips. Pre-produced clips
`are pulled on demand by a customer from special streaming servers. These programmes
`are usually encoded off-line and stored on the server for this purpose. There are cur-
`rently several hundred websites which provide the capability for customers to click and
`view an entire news story.
`
`In the push mode, both unicast and multicast streams can be generated. With unicast, the
`server generates a unique video stream and routes it to a single web viewer, after he/she
`has clicked on the chosen video clip. This method is largely prevalent today but is not
`the most efficient. In the case of multicast, a broadcaster’s web stream is first routed to
`local switching points and from there it is distributed to the users. In either method, mul-
`tiple web viewers can watch the same stream but, with multicast, the traffic on the Inter-
`net backbone is eased because the majority of the splitting occurs on a regional basis. In
`order to generate multiple streams, the stream is routed from the server to multiple com-
`puters known as splitters. By cascading multiple layers of splitters, thousands of simul-
`taneous streams can be generated. In order to broadcast sufficient streams over the
`Internet, large server “farms” are required. Examples of such farms are in use by Real
`Networks and Broadcast.com. CNN Interactive (CNNin) is supported by as many as 150
`servers, about 50 of which are front-end computers available for the users to type in a
`CNNin URL address. Twelve machines serve the advertisements and another six are
`used to stream the video.
`
`It should be pointed out that, especially with the more popular clips, thousands of clips
`may be requested at the same time. In order to cope with such a huge demand, large
`server farms must be utilized. Many ISPs offer this service, but the network traffic asso-
`ciated with these clip “players” requires much higher bandwidths than the access traffic
`to normal web pages. It is due to the extensive webcasting traffic that the Internet is
`often congested at peak times, thus turning the Web into a temporary “World Wait Web”
`network.
`
`7.
`
`Is the Internet suitable for real-time services?
`
`Whereas conventional television and radio transmission channels (both analogue and
`digital) usually provide very good quality, the Internet at present offers only barely-intel-
`ligible speech and low-definition pictures. This is because the Internet was not designed
`and built for real-time streaming transmissions. Rather, it was designed for the down-
`loading of files, for example from an FTP server: a connection between the server and
`the client is established and the data is transferred to a local storage device. After the file
`has been transferred in its entirety, the data can be processed locally using an application
`that can interpret the format of the data received. In a streaming configuration, on the
`other hand, the browser starts to reconstruct some parts of the incoming file while the
`loading of other parts is still in progress. As soon as the file has been received com-
`pletely, the connection between the server and the client is closed.
`
`EBU TECHNICAL REVIEW No. 282 – March 2000
`F. Kozamernik
`
`11 / 28
`
`PAGE 11 of 28
`
`WEBPOWER, INC.'S EXHIBIT 1006
`
`

`
`WEBCASTING
`
`The Internet is basically an asynchronous environment: the time taken between sending
`and receiving (and presenting) the information can vary in a non-predictable manner. In
`addition, there is no synchronization between the different kinds of data carried over the
`Internet.
`
`Some of the basic problems with the Internet, particularly from a webcasting viewpoint,
`are identified in Panel 2.
`
`8. Real-time protocols
`
`The most common Internet protocol is HTTP 1. This protocol is used for communica-
`tions between the server and the host, and enables the host to gain access to the files and
`drives on another host. However, this protocol is not designed to carry multimedia and it
`
`Panel 2
`Basic problems with webcasting
`
`Packet loss: The digital bitstream is split in packets called datagrams. If the Internet is con-
`gested or overloaded with traffic, or if a node or link has failed, packets may be lost or cor-
`rupted. The corrupted packets are discarded by the client. In real-time traffic, the missing
`packets cannot be retransmitted or reconstructed. While audio is very sensitive to packet
`continuity, the loss of video packets can be tolerated more easily.
`
`End-to-end packet delay: This consists of the processing delays at the sending and receiv-
`ing ends, plus the transmission time. In the case of traffic congestion, packets may have to
`queue in routing buffers during transmission. For full-duplex applications such as IP teleph-
`ony or videoconferencing, this delay should be limited to a few hundred milliseconds. For
`simplex applications, such as audio/video-on-demand or webcasting, it can be higher but
`should not exceed a few seconds. The time delay may affect the synchronization between
`different components of a multimedia presentation. This may be critical but the degree of
`criticality will vary from application to application.
`
`Delay jitter: Delay jitter is the variance in delay of consecutive packets. The time taken
`between sending and receiving (and presenting) the information can vary in a non-predicta-
`ble manner. In addition, there is no synchro