Homework - Multimedia Systems Module Solutions

Due July 8

  1. Using standard sampling rates for CD quality, how many bits per second are generated. Show your work.

    Standard sampling rate is 44,100 for 16 bits

    44,100 * 16 = .705 MBit/s

  2. Most experts agree that, while creating an audio production, it's best to keep all audio in digital format rather than converting back and forth to analog. Why?

    Because each conversion loses information in the conversion process

  3. What psychoacoustic principles does MPEG use to compress audio files.

    MPEG stores only values which humans hear best - doesn't store "softer" sounds near "loud" ones and uses such anomalies that we perceive sounds at higher frequencies to be louder etc.

  4. What is the Hz range of telephone speech?

    Human speech is in the range 300 Hz - 3 KHz. I found this at http://www.entnet.org/hearing.html by doing a search enginesearch on "speech" + "Hz range"

    Telephone speech is in the range 200 Hz - 3.4 KHz but I accepted anything reasonable here. I found this at http://www.cybit.com/telephon.htm I searched on "telephone speech" + "Hz range".

  5. How much space does it take to store an RGB 640x480 pixel picture?

    At its simplest, it's 640*480**24 = 7,372,800 = 921 Kbytes, but rgb can actually be stored in less.

  6. Good quality digital video data typically requires about how much space per minute in uncompressed form? in compressed form?

    Uncompressed =~ 80 MB/minute

    Compressed = ~ 400 KB/minute

  7. How much bandwidth (MBit/s) does it take to show a 900 KB/frame video at 30 frames/second?

    900 KB * 30 frames/s = 27,000 KB = (approx) .027 MBits/sec

  8. A typical local area network (e.g., ethernet, token ring) can transport how much information per second?

    About 10 Mb/s

  9. Can I (an American) play my home videos in Japan? in Finland? Why or why not?

    Yes, for Japan because they use NTSC, no for Finland which uses PAL (without expensive convertors)

  10. Why do people in Finland see less of the Cambodian troubles than do people in the US? (This has a multimedia, not a political answer!)

    25 frames/second in Finland < 30 frames/second in US (even when multiplied by the #lines)

    Send questions and comments to: Karen Lemone

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