Cover Image
close this book Expanding access to science and technology
close this folder Session 3: New technologies and media for information retrieval and transfer
close this folder Multimedia technology: A design challenge
View the document Abstract
View the document 1. Introduction
View the document 2. What are communication media and how do they differ?
View the document 3. Are human beings aware of the capabilities of different media?
View the document 4. What can the technology do now?
View the document 5. User centred or design centred?
View the document 6. The PROMISE multimedia interface project
View the document 7. How does one design a multimedia interface?
View the document 8. Some initial guidelines
View the document 9. Conclusions
View the document 10. Acknowledgements
View the document References

4. What can the technology do now?

The technology has moved rapidly in the past few years. The enabling technologies required to support a multimedia workstation go far beyond provision of the media themselves. A typical list [15] would include:

- Bit-mapped displays

- Audio and video support

- Device independent graphic rendering

- Control and synchronization

- Data compression

- Networking support

- High CPU/disk performance

- Authoring tools

To illustrate how far current workstations have come in being able to deliver such a collection of enabling technologies, Malleo-Roach cites the SUN SPARCstation as an example and provides the figures given in the table.

To give an idea of the costs associated with multimedia support, he suggests three possible configurations: "minimal," "enhanced," and "operational," with costs at about US$10,000 and US$35,000 for the first two (the third not yet being available). He expects an "operational" version to be available in 1995 for about US$10,000.

Bit-mapped display:

1152 x 900 bit-mapped display, most models providing 8- bit pseudo-colour

Device independent Graphics:

All SPARCstations support OpenWindows 2.0 with X11/ NeWs imaging

Audiovisual:

Every SPARCworkstation has built-in audio capabilities (8 kHz single channel. Videopix (a video frame grabber) is also available)

Data compression:

JPEG compression support for VideoPix. Uniflix-video compression/decompression tool kit for full-motion video

Control synchronization:

No complete and comprehensive solution, but a number of mechanisms are offered such as shared memory, interprocess communication, times, semaphores, and threads

Networking:

Client-server support. Multimedia as natural extension of the client-server model

Authoring:

A number of tools are available including HyperNeWS, Cats Meow, and Mediawrite.

High CPU/disk: Performance

Sufficient


Figure 2

Multimedia capabilities have also already arrived on most personal computers. There are multimedia extensions to Windows, and Apple now offers "Quick Time" on the Macintosh. Quick Time offers three new components: the Movie Toolbox, the Image Compression Manager, and the Component Manager (figure 2).

The Movie Toolbox provides facilities for creating, editing, and playing back moving images. The Component Manager enables new devices (such as VCRs, camcorders, etc.) to be attached as well as third vendor software modules. The Image Compression Manager uses one of three compression techniques for animation, video, and photos. The JPEG (Joint Photographic Experts Group) algorithm is used to compress photographs. It removes data that is redundant to the human eye. Compression ratios of between 500:1 and 5:1 can be achieved with a full screen colour image taking about 10 seconds to compress. The video compressor can achieve ratios of between 25:1 and 5:1 giving about 15 seconds of compressed video per megabyte. Boards are available for capturing video directly from cameras.

Compression techniques are essential since a standard television frame contains nearly 750,000 bytes of information. In uncompressed form, even a compact disc can only store 30-40 seconds of video. Furthermore, since a compact disc delivers data at an error free rate of 150 Kbytes per second, and 10 per cent of this needs to be reserved for audio, each picture needs to be reduced to about 5,000 bytes to maintain motion. This corresponds to a compression rate of 160. This can be done by DVI (Digital Video Interactive) algorithms.