Instructions to candidates:

Please pay close attention to the following instructions. There are two ways in which you may attempt this paper. You may:

EITHER

Answer 3 (three) questions from Part 1 and 1 question (one) from Part 2

OR

Answer 2 (two) questions from Part 1 and 6 (six) questions from Part 2

In either case, the questions you attempt should be worth a total of 80 marks.

Questions in Part 1 are worth a total of 25 marks each.

Questions in Part 2 are worth a total of 5 marks each.

_____________________________________________________________________

Part 1. (each question is worth a total of 25 marks)

1. The last decade has seen incredible advances in computer hardware technology. In 1989, the top-of-the-range Apple Macintosh cost some £Stg. 2500. That would have bought a Mac SE/30 - a 30MHz computer, with a 9" integral (built-in) monochrome monitor, 1Mb of RAM, and a 40Mb hard disk. Today, the same amount of money would purchase a PowerMac G3, running at 400 MHz, 128Mb RAM, a 9Gb hard disk, and a separate 24-bit colour, 17" monitor, and leave change in your pocket. User Interfaces, on the other hand, have changed comparatively little. If we assume that over the next decade, user interfaces will change with the magnitude that hardware has over the last decade, what might the user interface of the year 2009 look like?

[25 marks]

2. Explain the main deficiencies of TCP/IP when used to simultaneously deliver the same live continuous data to a number of clients on different remote networks. Which of these deficiencies does the Multicast Backbone overcome, and how?

[25 marks]

3a. Describe the differences between a lossless and a lossy compression algorithm.

[7 marks]

3b. Briefly explain the terms asynchronous, synchronous, and isochronous transmission modes.

[5 marks]

3c. What are the main characteristics of a multimedia operating system? Describe a scheduler for processes which manipulate continuous data with periodic intervals.

[ 13 marks]

4a. Explain the quantization step in general compression and decompression techniques. How does quantization reduce storage space/bandwidth requirements? Explain how the quantization tables for a JPEG image are further compressed.

[15 marks]

4b. What is the purpose of MPEG B-frames? Which type of compressed MPEG video frame supports rapid scanning of the video stream (e.g., to provide fast forward/rewind in a video window), and why are the other frame types not suitable?

[10 marks]

5. Describe in detail the H.261 compression standard for video-conferencing.

[25 marks]

Part 2 (each question is worth 5 marks)

6. Briefly discuss general synchronization issues in distributed multimedia systems.

7. Can the MBONE's Real-time Transfer Protocol (RTP) ensure the synchronous transmission of data? Justify your answer.

8. If a MIDI file is used to drive the synthesizer that created it, will the sound played back be identical to the original sound? Explain your answer.

9. MPEG-1 uses two sources of synchronization information. What are they, and in what circumstances are they used?

10. Briefly describe the Boolean Retrieval Model for Information Retrieval.

11. What are the advantages and disadvantages of the stereotype approach to user modeling?

12. What are the advantages of adaptive hypermedia when compared to traditional (or non-adaptive) hypermedia?

13. Briefly describe the Adaptive Differential Pulse Code Modulation (ADPCM) coder for audio coding.

14. Describe some of the problems normally enountered with typical Head-Mounted Displays used to interface with virtual environments.