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Sound and Compression (sound (conversions (analogue to digital (you need a…
Sound and Compression
sound
conversions
analogue to digital (you need a sound card)
sound waves converted into voltage changes (e.g into a microphone)
voltage sampled at intervals = sample rate
values converted into binary
collection of binary numbers stored as sound files
digital to analogue
stored sound recreated using digital to analogue converter (DAC)
Converts binary numbers back into a changing voltage
voltage makes speakers vibrate to reproduce sound
sampling rate
number of samples taken per second (measured in Hertz)
Higher Sample Rate
Better Quality sound recorded
Larger File size
More samples makes the recording accurate to the actual sound
Bit Rate
Bit Rate is the number of bits used to store each sound saple
Higher Bit Rate
Better Quality of Recording
Larger File Size
More Bits per Sample means higher quality sound
compression
why
to reduce file size
for sending
to reduce download times
increase storage
Best use of bandwidth
increase speed of transmission
types
lossy
Data IS removed to reduce file size
usually no noticeable lack of quality
data CAN'T be put back
Generally used for images(jpeg) audio(mp3) video(mpeg)
lossless
none of the data is removed
original file can be recreated
Increased processing overheads