Overview of Video On Demand Systems 13778 Essay Example

organizations to make informed decisions and to take the appropriate action to current events. Multipoint multimedia teleconferencing and video servers offer the required solution. As defined here, it involves a user-specified mix of traditional voice, motion video, and still-image information in the same session.

The images can be documents, spreadsheets, simple hand-written drawings, highly-detailed color schematics, photographs or video clips. Participants can access the same image at the same time, including any changes or comments on that image that are entered by other participants. Video servers allow users to view stored video files of specific events, conferences, news clips and important information in near realtime. The benefits are obvious. Instead of text interpretation of a video clip, all interested parties can access the information. Little is left to verbal interpretation since all users have access to the original video. In the case of video clips, a persons actions, verbal tones, mannerisms and reactions to events around them can be viewed and interpreted. Increased productivity, reduced cost, and reduced travel time are the primary benefits while proprietary technology and solutions are specified as the primary inhibitors of using video on demand products and services. Starting with Standards While multimedia teleconferencing and video servers promise to revolutionize vital everyday corporate tasks such as project management, training, and communication between geographically-dispersed teams, it is clear that standards-based solutions are a prerequisite for volume deployment. Standards ensure that end-users are not tied to any one supplier's proprietary technology.

They also optimize capital investment in new technologies and prevent the creation of de facto communication islands, where products manufactured by different suppliers do not interoperate with each other or do not communicate

over the same type of networks. When adopted and adhered to by equipment suppliers and service providers alike, standards represent the most effective and rational market-making mechanism available. ISDN, fax, X.25, and GSM are a few obvious examples of standards- based technologies. Without internationally-accepted standards and the corresponding ability to interoperate, the services based on these technologies would almost certainly languish as simple curiosities. Interoperability is particularly important in multipoint operation, where more than two sites communicate. A proprietary solution might suffice if two end users want to communicate only with each other; however, this limited type of communication is rare in today's business world. In typical business communications, multiple sites, multiple networks, and multiple users have communications equipment from multiple manufacturers, requiring the support of industry standards to be able to work together.

This interoperability is also critically important when a video server may be transmitting data across a WAN to multiple users, in multiple sites. Perhaps the most important effect of standards is that they protect the end users' investments. A customer purchasing a standards-based system can rely on not only the current interoperability of his equipment but also the prospect of future upgrades. In the end, standards foster the growth of the market by encouraging consumer purchases. They also encourage multiple manufacturers and service providers to develop competing and complementary solutions and services.

Two Standards, One Goal Fortunately, standards for multimedia teleconferencing are at hand. Working within the United Nations-sanctioned ITU's Telecommunications Standardization Sector, two goals have been achieved: the T.120 audiographics standards and the H.320 videotelephony standards. T.120, H.320 and H.261 are "umbrella" standards that encompass the major aspects of the multimedia communications

standards set. The T.120 series governs the audiographic portion of the H.320 series and operates either within H.320 or by itself. Ratification of the core T.120 series of standards is complete. These recommendations specify how to use a set of infrastructure protocols to efficiently and reliably distribute files and graphical information in a multipoint multimedia meeting. The T.120 series consists of two major components. The first addresses interoperability at the application level, and includes T.126 and T.127. The second component includes three infrastructure components: T.122/T.125, T.124, and T.123. The H.320 standards were ratified in 1990, but work continues to encompass connectivity across LAN-WAN gateways.

The existing H.320 umbrella covers several general types of standards that govern video, audio, control, and system components. With many businesses using LANs to connect their PCs, the pressure is on to add videoconferencing to those networks. Since the H.320 standards currently address interoperability of video conferencing equipment across digital WANs, it is a logical and necessary step to expand the standards to address LAN connectivity issues. As the work to expand H.320 continues, it remains the accepted standard. Both the T.120 and the H.320 series of standards will be improved upon and extended to cover networks and provide new functionality. This work will maintain interoperability with the existing standards. Standards First Standards as complex and universal as the H.320 and T.120 series need a coordination point for the interim steps a proposal takes on its way to becoming a standard.

The IMTC is an international group of more than 60 industry-leading companies working to complement the efforts of the ITU-T with an emphasis on assisting the industry to bring standards-based products successfully

to the market. Its goals include promoting open standards, educating the end user and the industry on the value of standards compliance and applications of new technologies, and providing a forum for the discussion and development of new standards. The IMTC is approved as an ITU-T liaison, and interfaces with the ITU-T by participating in standards discussion and development, feeding information and findings into the appropriate ITU-T Study Groups. The Standards First initiative encourages multimedia equipment manufacturers to start with compliance to at least the H.320 T.120 and H.261 standards described above.

Further standards compliance is recommended but optional, and manufacturers will still have the ability to differentiate their products with proprietary features, creating Standards Plus products. Compliance to the minimum H.320/T.120 standards will ensure a basic level of connectivity across equipment from all participating manufacturers. Summary Standards have played an important part in the establishment and growth of several consumer and telecommunications markets. By creating a basic commonality, they insure compatibility among products from different manufacturers, thereby encouraging companies to produce varying solutions and end users to purchase products without fear of obsolescence or incompatibility. The work of both the IMTC and the ITU-T represents an orchestrated effort to promote a basic connectivity protocol that will encourage the growth of the multimedia telecommunications market. The Standards First initiative, which has been accepted by several industry leading companies, requires a minimum of H.320, H.261 and T.120 compliance to establish that basic connectivity.

Manufacturers are then able to build on the basic compliance by adding features to their products, creating Standards Plus equipment. By insuring interoperability among equipment from competing manufacturers, developers, and service providers, Standards First ensures

that a customer's initial investment is protected and future system upgrades are possible. Content Preparation: The first step in a VOD system is the entry of Video information. The possible sources of video information in a large scale (Government) VOD system include: Recorded and Live video, Scanned Images, EO, IR, SAR collected Images. Recorded video is the primary concern of this paper. Since latency and jitter do not effect Imagery data types they will be noted but not expanded upon. Live video is the primary concern of video conferencing, but the requirements do overlap with recorded (VOD) video.