Image/Sound Representation

• Metadata is data about the data, such as the file size, type, and location of the file
• Image file size = colour depth * image width * image height
• How do you find the colour depth?

  $\log_2$ (colours) and round up
• What is the difference between digital and analogue data?

  Analogue data is continuous, digital is discrete
• How does an ADC work?

  1. Analogue sounds are sampled
  2. Each sample is quantised
  3. Value is stored as binary
• How does an DAC work?

  
  

  Binary value converted to analogue (AC) current
• What is the sample resolution?

  The number of bits used to record each amplitude
• Sound file size = sample rate * resolution * length
• What is Nyquist Theorum?

  Sample rate > 2 x frequency
• What is a MIDI?


  Used with electronic musical instruments to store music
• Advantages of MIDI over sampling?

  Easy manipulation without quality loss and are often smaller file size.
• Disadvantages of MIDI


  Cannot store speech and less realistic sound than sampled