The mete multimedia covers a wide ...

The mete multimedia covers a wide range of applications, ranging from simple image-in-text word processors in consequence of video conferencing. The qualifier "real-time" confines the applications to those that impose timing constraints onward the underlying delivery system, so as:

* Conferencing systems using synchronized video, audio, and shared computer data

* alien training and information databases containing digital video and audio data

* unallied control or manipulation of computer-generated moulds and robotic machines.

As desktop computer make improvement in power and decrease in price, and networks expand as well-as; not only-but also; not only-but; not alone-but in area and in data transfer rates, as it was applications are likely to have a major impact forward all desktop computer systems and workgroup LANs in the mid to late 1990 The factors that indicate a takeoff in multimedia can be divided into sum of two units groups: user demand and the progression in a continuously ascending gradation of appropriate technology.

User Demand for Multimedia Applications

A major demand is for humans to interact with foreign systems. This started in the fields of education and training. Computer-based training, which used to use analog video and audio, has become a mature market, and is moving rapidly towards using digital media. In the that will be this data may need to be held centrally likewise that it can be updated easily. Training applications could be networked to this central source. This requires that reign over data be transmitted to a server with depressed delay, and that the server have the ability to transmit multimedia data back to the desktop, also with reasonable delay.

Applications are growing in the scientific, engineering, and medical domains in which, for example, humans interact in real time with foreign models and image data. These applications also place significant timing constraints upon the underlying network.

Perhaps the in the greatest degree exciting growth area is in the support of real-time human conversation. Teams separated geographically ne of that kind systems for activities traditionally performed upon a single site, such as meetings, training, marketing, and support. As an example, HP has already relased a station of collaborative workgroup tools that includes imaging, digital audio, and shared data.

System so as these are a natural increase from video conferencing systems. It is remarkable that across half of all Fortune 1000 companies use boardroom-based conferencing facilities, given that until lately they cost over $20,000 through node and were relatively undressed in operation. The possibility of low-cost desktop-based conferencing a whole s that integrate with existing computer applications has to be seen as extremely attractive to companies and teams distributed across several sites.

Multimedia Technology

Demand for desktop multimedia applications have relationed over networks can only be satisfied if the technology exists to support it. There areas are critical:

* The increase of standards for video and audio coding that allow low-cost implementation and fast transmission

* The increase of low-cost wide-area networks (WANs)

* The unravelling of consistent interfaces to multimedia technology, the two from WANs to appropriate LANs, in the same state [i]or[/i] condition as 100VG-AnyLAN, and from LANs to applications.

Video and Audio Coding Standards. The ISO and the ITU-T (formerly CCITT) have produc several standards for audio and video coding algorithms, similar as MPEG and H.261 for video conferencing and video telephony and JPEG for the compression of still images (now being widened to full-motion video). Since all these algorithms are based in succession discrete cosine transformations, low-cost chipsets that support all three are being perform the operations indicated ined by several manufacturers. Audio CD-quality arrangements are already becoming standard features of workstations and PC and many manufacturers have released plans to incorporate hardware support for full-motion video. The increasing power of workstation and PC microprocessors is also making software compression and decompression of full-motion video feasible. HP's rife workstations can already perform decompression of full-motion video. Real-time compression is likely to run after in a few years.

Wide Area Networks (WANs). The price of WAN services has fallen dramatically in the last not many years. For example, a long-distance video conferencing link that was around US$1500 by hour in 1984 now charges in the range of U $12 to $30 through hour. In addition, there is increasingly widespread availability of a variety of dial-up WAN services.(1)

There is also a significant effort going into the disclosure of wide area broadband services, perhaps leading to a Broadband Integrated Services Digital Network (B-ISDN) from the end of the decade.

Consistent Interfaces. For multimedia to work effectively throughout wide area networks and a variety of campus and local-area networks, there is a ne for consistent interfaces between networks. 100VG-AnyLAN alone covers a portion of a wide area networked system

Various bodies are looking at other areas of network schemes Fig. 1 illustrates the situation schematically.

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