MM_BSC_SOLNS_2007

MM_BSC_SOLNS_2007 - CM0340 SOLUTIONS CARDIFF UNIVERSITY...

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Unformatted text preview: CM0340 SOLUTIONS CARDIFF UNIVERSITY EXAMINATION PAPER Academic Year: 2006/2007 Examination Period: Autumn Examination Paper Number: CM0340 SOLUTIONS Examination Paper Title: Multimedia SOLUTIONS Duration: 2 hours Do not turn this page over until instructed to do so by the Senior Invigilator. Structure of Examination Paper: There are ?? pages. There are ?? questions in total. There are no appendices. The maximum mark for the examination paper is 80 and the mark obtainable for a question or part of a question is shown in brackets alongside the question. Students to be provided with: The following items of stationery are to be provided: ONE answer book. Instructions to Students: Answer 3 questions. The use of translation dictionaries between English or Welsh and a foreign language bearing an appropriate departmental stamp is permitted in this examination. 1 PLEASE TURN OVER CM0340 SOLUTIONS Q1. (a) Why is data compression desirable for multimedia activities? Data is high resolution in both temporal and/or spatial domains. [1] Storgage, bandwidth and processing limitations need compressed data. [1] 2 MARKS BOOKWORK (b) Briefly outline the four broad classes of approach that one may exploit to compress multimedia data. Do not detail any specific compression algorithms . Compression basically employs redundancy in the data: Temporal in 1D data, 1D signals, Audio etc. correlation between sequential data points. [2] Spatial correlation between neighbouring pixels or data items in 2D. [2] Spectral This uses the frequency domain to exploit relationships between frequency of change in data. E.g. in video/imagery, correlation between colour or luminescence components. [2] Psycho-visual exploit perceptual properties of the human auditory/visual sys- tem. [2] 8 MARKS BOOKWORK Give one example of a compression algorithm for each class. EXAMPLES: Temporal Any Audio/Video compression method, Zero length suppression, pattern substitution, Pulse Code Modulation (a few variants), MPEG Audio, MPEG Video, H.264 [1] Spatial Any Image/Video compression algorithm, GIF, JPEG, MPEG, H.264. [1] Spectral JPEG, MPEG, H.264. [1] Psycho-visual MPEG audio, MPEG Video, JPEG (colour conversion). [1] 4 MARKS BOOKWORK 2 CM0340 SOLUTIONS (c) Consider the following sequence of 8-bit integers: 4 6 9 11 13 12 13 14 12 11 Show how you would code this sequence using: i. Differential Pulse Code Modulation (DPCM) Sequence: +4 +2 +3 +2 +2 -1 +1 +1 -2 -1 [3] ii. Differential Pulse Code Modulation with delta modulation Sequence: 1 1 1 1 1 0 1 1 0 0 [3] 1 = increase/equality in data, 0 = decrease in data iii. Adaptive Differential Pulse Code Modulation (ADPCM) with window size of 3 Averaged Sequence: 4 5 6 9 11 12 13 13 13 13 12 11 ADPCM Sequence: 4 +1 +1 +3 +2 +1 +1 0 0 0 -1 -1 [4] 10 Marks UNSEEN application of knowledge/bookwork Comment on the relative efficiency of these methods on the above sequence....
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MM_BSC_SOLNS_2007 - CM0340 SOLUTIONS CARDIFF UNIVERSITY...

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