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Ch.4 Multimedia Elements and Digitization (4.2 Analogue Data and Digital…
Ch.4 Multimedia Elements and Digitization
4.1 Digital Multimedia Elements
Audio
BIt resolution:bit resolution increases,audio quality increase
sampling rate:sampling rate increases,audio quality increase
common formats:
MP3:small file size,supports streaming
M4A:high quality,quite large file size,suports streaming
WAV:large file size
AAC:high quality,supports streaming
WMA:windows ato format,supports streaming
Video
Graphics
Bitmaps
Pixels:Smallest picture element
Resolution:Number of pixels per inch(screen)
Resolution:Dimension od image(e.g.800x600)
Colour depth:number of bits used to
Common file formats:
JPG:
PNG:
GIF:
TIF:Used in fax and medical field
BMP:Large file size
Vector graphics:Vecctor objects are defined by mathematical formula
4.2 Analogue Data and Digital Data
A lot of information is transmitted in analogue form such as sound
all electronic devices handle data in binary forms
digital data can be represented in sequences of binary numbers
makes operations of electronic device on digital data highly precise and efficient
4.23 sampling and quantization
it is the process of converting the attribute of each sample data into a digital code (which is usually represented by binary number) using a predefined scale
it is the process of obtaining discete sample data from the continuous analogue signal for every fixed time interval
quality of digital audio is determined by sampling rate the bit resolution the num of channels
quality of digital video:the frame size frame rate video compression alogorithm
image quality :resolution color depth compression ratio
4.22 Applications of Digital Data in IT
Sampling
Quantization
4.24 Converson of Analogue Multimedia Elements
Audio
Image
Video
