4.2 Analogue Data ad Digital Data Sara Tang S.4D
The Definition of Digital Data • Digital data is discrete, compared to continuous • It is the data stored in the form of binary numbers,usually “0” and “1” • E.g. a DVD player
The Definition of Analogue Data • As humans, we perceive information in analogue form. • Everything we see and hear is a continuous transmission of information to our senses. • This continuous stream is what defines analogue • E.g. a video cassette recorder.(VCR)
Analogue vs Digital Film photos Sound Record Digital photos MP3
Analogue vs Digital Watch or Clock with hands Pointer-reading instrument Watch or clock displaying figures Instrument with digital output display
Sampling • The process of obtaining discrete sample data from the analogue data for every fixed time interval • Quality is determined by sampling rate • E.g. video sampling
Quantization • Quantization is the process of convertiing a continuous signal into digital codes by a set of discrete symbols or integer values.
Conversion of Analogue Multimedia Elements. • Audio -Sound is analogue. -it is converted by a sound card to a digital format and vice versa. -by Analogue Digital Converter(ADC) and Digital Analogue Converter(DAC)
Analogue Images -can be converted into digital images by a scanner -Its quality is determined by its resolution, colour depth and compression ratio.
Video - can be converted into a sequence of digital images by a video capture card. -Charge-coupled devices(CCD) are responsible of convertion in digital video cameras and webcams.
Conversion Betweem Analogue Data and Digital Data Analogue data has to be converted into digital form before it can be used in the computer. Digitization -sampling -quantization