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4.1 Digital Multimedia Elements, Ch.4 Multimedia Elements and Digitization…
4.1 Digital Multimedia Elements
Audio
are the digitised data of
speech
any kind of audio signals
music
key elements that affect the quality
bit resolution
sampling rate
stereo audio contains
left sound track
right sound track
mono audio contains
only one sound track
Examples of uncompressed audio and compressed audio file formats
uncompressed
WAV
compressed
WMA
MP3
Video
a sequence of full-motion images together with sound tracks
file size of it can be very large
factors affecting the size of a video file
Frame rate
Duration
Frame size
Compression
Colour depth
the higher the frame size and frame rate
the better the video quality
the larger the file size
a particular compression method has its own specification of
compression ratios
frame sizes
frame rates
Examples of uncompressed video and compressed video file formats
uncompressed
AVI
compressed
MPEG-1
MPEG-2
WMV
Graphics
Ch.4 Multimedia Elements and Digitization
4.2 Analogue Data and Digital Data
Characteristics
Accuracy of information
A:Accuracy depends on the sampling technique used
D:Lower accuracy
Efficiency on transmission
A:High
D:Low
Mode of data access
A:Mostly sequential access
D:Direct access is possible
Efficiency on data storage
A:Low
D:High
Efficiency on data analysis
A:Low
D:High
Way of measurement
A:Continuous signals of amplitude and frequency of the source are measured
D:Information is represented in discrete form
Replication
A:Absolute replication is nearly impossible
D:Absolute replication and error-free transmission of data are possible and easy
Applications of digital data in IT
All electronic devices including computers and modern data transmission channels handle data in binary forms
This makes operations of electronic devices on digital data such as these examples precise and efficient.
storage
transmission
manipulation
duplication
Conversion between analogue data and digital data
Digitalization
is the process of converting analogue data into digital data
Digitization involves two procedures
Sampling
The process of obtaining discrete sample data from the continuous analogue signal for every fixed time interval
Quantization
The process of converting the attribute of each
sample data into a digital code using a predefined scale
Conversion of analogue multimedia elements
Image
Video
Audio
A: Analogue data D: Digital data