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Digital Multimedia Elements - Coggle Diagram
Digital Multimedia Elements
Audio
Digitized data of audio signals
Quality
Sampling Rate
measured in Hz
samples taken each second
Bit Resolution
Amplitude of an audio signal
The higher, the more precise
Sound Tracks
Mono Audio
Only one sound track
Stereo Audio
Left and Right sound track
Compression
Compressed
Uncompressed
Conversion
Done by two chips
DAC(Digital Analogue Converter)
ADC(Analogue Digital Converter)
Audio playback cannot be the same as original
Graphics
Bitmaps
Pixels
A pixel is the smallest picture element
A collection of pixels arranged in rows and columns forms Bitmap Image
Properties
Number of bits of Colour used to represent is Colour Depth
Number of pixels is measured by ppi (Pixel per Inch)
Compression decreases the quality and size
Vector Graphics
Objects
Can be a line, a shape or a string of text
Defined by mathematical formulae
Object Properties include Fill Colour, Outline Thickness....
Can be rescale and modify easily
Properties
Not suitable for representing complicated pictures
suitable for representing simple charts, line arts...
File size does not grow rapidly and is much smaller
Conversion
Analogue to Digital
scanned image cannot be same as original
Stored as bitmap graphics
Digital to Analogue
E.g. Projecting image on screen
Output image not same as digital one
Video
Factors affecting the size
Duration
play time
Compression
Reduction of quality
Frame Rate
Number of frame displayed each second
Frame Size
Number of pixels on each frame
Colour Depth
Number of bits used to represent a pixel
Conversion
Video Capturing Devices
TV tuner card
Cameras
Contain CCD(Charge-Coupled Devices)
Digital Video can be transferred through USB or FireWire
A sequence of full-motion images with sound tracks
Analogue and Digital
Analogue
High rate of transmission error
Accuracy depends on sampling
Low efficiency on storage
Data is lost, impossible absolute replication
Continuous signals of amplitude and frequency
Low efficiency on data analysis
Mostly sequential access
Conversion
as Digitization
Sampling
Obtaining sample data every fixed time interval
Quantization
Converting attribute into a digital code
usually in binary number
Digital
High Efficiency on storage
Low rate of transmission error
Represented in Discrete form(0 or 1)
Lower Accuracy
Absolute replication and error-free transmission
High data analysis efficiency
Direct access is possible
Applications
Handle datas in binary forms
Digital datas can be represented in sequence of binary numbers
highly precise and efficient
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