Multimedia Systems (contd..)

Networking standards (Contd..) • ATM – originally designed for broadband applications in public networks. • Switch-based, cell-relay technologies that connects individual nodes over a dedicated bandwidth. • Inherently applicable to high-speed (>100 Mbits/sec) real-time multimedia communications in LANs. • It is a method of multiplexing and relaying 53-byte cells containing either text data packets or compressed images,

• FDDI – Fiber Distributed Data Interface n/w • An excellent candidate for use as highperformance backbone networks to complement and extend current LANs. • ATM vs FDDI II – viewed as technologies that can reduce congestion in multimedia n/ws. Evolving technologies for Multimedia systems • Hypermedia Documents – by the definition contain, in addition to text, embedded or linked multimedia objects such as image audio, hologram, or full-motion video. • The network speed and computing efficiency with which these hypermedia documents can

- Hypertext, implements the organization of non-sequential data by natural associations of information rather than hierarchical filing structures as in paper-based text documents. - Hypertext systems allow authors to link information together, create information paths through a large volume of related text in documents, annotate existing text, and append connections, or links, allow readers to move from one location to another in a document or to other documents. - fast and easy searching and reading of selected excerpts through text spanning up to

• Issues (due to multiple users start sharing the same documents) - maintaining version control, - managing organized access to documents, & - locating documents with the required information become critical in a networked environment where multiple users are concurrently accessing the same knowledge base. - storage, needs to store only references to the documents. • Hypermedia document – a set of pointers to help locate the various elements of the document on the network, an approach that fits

• Hyperspeech – speech synthesis and indexing of speech is an important component of multimedia systems. • For eg., a mail message can be used to generate a hyperspeech file that a user can begin to navigate on a selective basis. Instead of having to listen to a synthesized recording of the entire message, a user can jump from concept to concept, following a variety of threads of thought. • Requires substantial processing power. Highperformance microprocessors and DSPs and

• HDTV and UDTV (High Definition Television & Ultra Definition Television) • Parallel development in the electronics industry is to raise the resolution levels of commercial television broadcasting. • Better known TV broadcasting standards are, NTSC (National Television Standard Committee) PAL ( Phase Alternate Line) SECAM (System Couleur avec Memoire) NHK (Nippon Hoso Kyokai)

• Developments for HDTV & UDTV benefit the computer industry as the basic technologies for display & communications merge. • Development in progress for digital codecs, modulators, and demodulators for terrestrial NTSC, & wide-band satellite broadcasting. • CAD/CAM & imaging technology use resolutions of 150 dpi/approximately 3000 pixels on a 20inch-wide-display – equals digital UDTV quality. • A typical display image with a 2550x3300 pixel resolution - 7.5 Mbits for uncompressed storage. • Gray-scale /color image of the same size –

• 3D technologies and Holography – concerned with 2 areas: pointing devices and displays.