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Unformatted text preview: EECS 314 Fall 2007 HW 10 Problem 1 Student's name ___________________________ Discussion section # __________ (Last name, first name, IN INK) 2007 Alexander Ganago Page 1 of 2 The big picture As you know from lecture notes, music on CD is recorded with 16 or 20bit resolution, at the sampling rate of ~ 44 kHz. As you know from reading the labels, a blank CD has the capacity of 700 MB (megabytes; 1 Byte = 8 bits; 1 MB ~ 10 6 Bytes) and is rated for 80 minutes of music recording. In this Problem, you will put 2 and 2 together in order to see whether all of the above numbers make sense. Problem Part 1 (10 points) Assume that the music is recorded in two channels (stereo = left and right) that have the same resolution of 16 bits and the same sampling rate of 44 kHz. Calculate the amount of memory in MB required to record 1 minute of music. Your answer: _______________________ MB per minute of music Assume that a blank CD has the capacity of 700 MB. Calculate how many minutes of music can be stored on the CD. Your answer: T = _______________________ minutes on CD If your answer above is less than 80 minutes, it means that a data compression algorithm is used to record the data on music CDs. The compression can be easily quantified: for example, if you estimate the needed memory as 1 MB and the actual record requires only 0.8 MB, then the compression ratio equals 1/.8 = 1.25, which is very modest compared to that used in MP3 technology. Discuss your answer: if you found T > 80 minutes, no compression is needed. If, however, you found T < 80 minutes, compression is needed, and you are asked to calculate the compression ratio. Your answer on compression: _______________________________________________ Part 2 (5 points) Repeat Part 1 for 20bit music recording. Your answer: _______________________ MB per minute of music Your answer: T = _______________________ minutes on CD Your answer on compression: _______________________________________________ EECS 314 Fall 2007 HW 10 Problem 1 Student's name ___________________________ Discussion section # __________ (Last name, first name, IN INK) 2007 Alexander Ganago Page 2 of 2 Part 3 (10 points) An important characteristics of sampling is the bit rate, usually expressed in kilobits/second, or kbit/sec, which is calculated for stereo recording as the product bits/sample number of samples/second 2 channels / 1000 bits/kilobit Calculate the bit rate for CD recording with 16bit resolution. Your answer: _______________________ kbit/sec for 16bit CD recording Compare your result with the popular MP3 standard 128 kbit/sec: calculate the ratio of bit rates in CD and MP3 recordings. Your answer: the ratio of bit rates (CD/MP3) equals _______________________ Assume a blank disk capacity of 700 MB, calculate the duration of music recordings in MP3 format that can fit on that disk. Express your result in seconds, as well as in hours and minutes (rounded to a single minute)....
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 Fall '07
 Ganago

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