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Old 03-28-2007, 10:45 PM   #32
Longbongcilvaringz
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Originally Posted by Infinity tha God View Post
COPY AND PASTE _


something i learned in school that i thought was interesting.

mp3 audio
mpeg layer 3
motion picture experts group

cd quality- 44.1kHz, 16 bit resolution

a 2 track, stereo interleaved file
x
44.1kHz (or 44100 samples per second)
x
16 bits
___________
1411200 (samples per bit)

itunes offers their mp3's at a rate of 128kbps.

divide the number above by 128kbps ( 128000 bits per second) and you get 11.025. so the mp3 is compressed at a ratio of about 11:1.
for every 11 bits of dynamic range, you are getting 1 bit back.

now do the opposite and divide 128000 by 1411200.
0.0907029.......
converting that into a percentage, we get about 9%. this is how much is left of the original audio at 128kbps.
so 91% of the audio signal has been removed from the original waveform.
the data is removed permanently, based on priority.
low priority to keep masked frequencies, and frequencies outside of 20Hz-20kHz (the range of human hearing).
highest priority to keep are frequencies from 1kHz- 4kHz (mid range).


this is common knowledge, not the specifics, but the whole point of mp3's was to get rid of all the information that wasnt "essential".

part of why i actually buy music, an mp3 never sounds the same through decent equipment.
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