MM_BSC_SOLNS_2003

MM_BSC_SOLNS_2003 - CM0340 CARDIFF UNIVERSITY EXAMINATION...

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CM0340 1 CARDIFF UNIVERSITY EXAMINATION PAPER SOLUTIONS Academic Year: 2002-2003 Examination Period: Autumn 2002 Examination Paper Number: CM0340 Examination Paper Title: Multimedia Duration: 2 hours Do not turn this page over until instructed to do so by the Senior Invigilator. Structure of Examination Paper: There are four pages. There are four questions in total. There are no appendices. The maximum mark for the examination paper is 100% 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 THREE questions. The use of translation dictionaries between English or Welsh and a foreign language bearing an appropriate departmental stamp is permitted in this examination.
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CM0340 2 1. (a ) What is MIDI? Definition of MIDI: a protocol that enables computer, synthesizers, keyboards, and other musical device to communicate with each other. 2 Marks – Basic Bookwork (b) How is a basic MIDI message structured? Structure of MIDI messages: MIDI message includes a status byte and up to two data bytes. Status byte The most significant bit of status byte is set to 1. The 4 low-order bits identify which channel it belongs to (four bits produce 16 possible channels). The 3 remaining bits identify the message. The most significant bit of data byte is set to 0. 4 Marks – Basic Bookwork
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3 (c) A piece of music that lasts 3 minutes is to be transmitted over a network. The piece of music has 4 constituent instruments: Drums, Bass, Piano and Trumpet. The music has been recorded at CD quality (44.1 Khz, 16 bit, Stereo) and also as MIDI information, where on average the drums play 180 notes per minute, the Bass 140 notes per minute, the Piano 600 notes per minute and the trumpet 80 notes per minute. (i) Estimate the number of bytes required for the storage of a full performance at CD quality audio and the number of bytes for the Midi performance. You should assume that the general midi set of instruments is available for any performance of the recorded MIDI data . CD AUDIO SIZE: 2 channels * 44,100 samples/sec * 2 bytes (16bits) * 3*60 (3 Mins) = 31,752,000 bytes = 30.3 Mb Midi: 3 bytes per midi message KEY THINGS TO NOTE Need to send 4 program change (messages to set up General MIDI instruments) = 12 bytes (2 marks) Need to send Note ON and Note OFF messages to play each note properly. (4 marks) Then send 3 mins * 3 (midi bytes) * 2 (Note ON and OFF) * (180 + 140 + 600 + 80) = 18,000 bytes = 17.58 Kb. 8 Marks – Unseen 2 for CD AUDIO 6 for MIDI (ii) Estimate the time it would take to transmit each performance over a network with 64 kbps.
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MM_BSC_SOLNS_2003 - CM0340 CARDIFF UNIVERSITY EXAMINATION...

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