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Chapter 3 Data Storage (3-4 Storing Audio (3.4.3 Encoding (Some systems…

- - - - Range: 0 ... (2^N – 1)
      - Process
        
        The number is changed to binary.
        
        If the number of bits is less than N, 0s are add to the left of the binary number so that there is a total of N bits.
      - Application of unsigned integers
        
        Counting
        
        Count from 1 or 0
        
        Addressing
        
        Store the address of a memory location inside another memory
        
        Storing other data types
        
        Stored as bit-patterns
    - - Range: –(2^N–1 – 1) ... + (2^N–1 – 1)
      - Process
        
        The number is changed to binary; the sign is ignored.
        
        If the number of bits is less than N–1, 0s are add to the left of the binary number so that there is a total of N–1 bits.
        
        If the number is positive, 0 is added to the left (to make it N bits). If the number is negative, 1 is added to the left.
    - - Range: –(2^N–1 – 1) ... +(2^N–1 – 1)
      - Process
        
        The number is changed to binary; the sign is ignored.
        
        0s are added to the left of the number to make a total of N bits.
        
        If the sign is positive, no more action is needed. If the sign is negative, every bit is complemented.
    - - Almost all computers use two’s complement representation to store a signed integer in an n-bit memory location.
      - Range: –(2^N–1) ... +(2^N–1 – 1)
      - Process
        
        The number is changed to binary; the sign is ignored.
        
        If the number of bits is less than N, 0s are added to the left of the number so that there is a total of N bits.
        
        If the sign is positive, no further action is needed. If the sign is negative, leave all the rightmost 0s and the first 1 unchanged. Complement the rest of the bits.
  - - - (Sign)(Fixed-point part)×Base^(shifter)
      - Although a fixed-point representation can be used to represent a real number, the result may not be accurate or it may not have the required precision.
    - - Truncation Error
      - Rounding floating-point numbers
        
        Round to Nearest
        
        Rounds to the nearest value; if the number falls midway it is rounded to the nearest value with an even (zero) least significant bit, which occurs 50% of the time (in IEEE 754-2008 this mode is called roundTiesToEven to distinguish it from another round-to-nearest mode)
        
        Round toward 0
        
        Round toward +∞
        
        Round toward −∞
- - - - It uses 7-bits to represent:
        
        94 Graphic printing characters
        
        34 Non-printing characters
      - Some non-printing characters are used for text format
        (e.g. BS = Backspace, CR = carriage return).
      - Other non-printing characters are used for record marking and flow control (e.g. STX and ETX start and end text areas).
      - The upper and lowercase characters are distinguished by
        only 1 bit. (A →1000001; a →1100001)
      - 0000000 → null character; 1111111 → delete character
    - - Available in many modern applications
      - For encoding characters in world languages
- - - - Several bit rates are specified in the MPEG-1 Layer 3 standard: 32, 40, 48, 56, 64, 80, 96, 112, 128,
        144, 160, 192, 224, 256 and 320 kbit/s,
        and the available sampling frequencies are 32, 44.1 and 48 kHz.
        
        44.1 kHz is almost always used,
        because this is also used for CD audio
        
        Uncompressed audio as stored on
        a compact disc has a bit rate of 1,411.2 kbit/s
        (16 bits/sample×44100 samples/second
        ×2 channels÷1000 bits/kilobit).
- - - - True Color
        
        Uses 24 bits to encode a pixel.
        
        JPEG (Joint Photographic Experts Group)
      - Indexed Color or Palette Color
        
        GIF (Graphic Interchange Format)
        
        Uses only 256 colors of True Color.