Mp3s: The Magic behind them.

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Here is an article regarding MP3 file format & how it works? The authors have,in writing this article,dispelled the aura of mystery around them. 


Intro:
Since the invention of Mp3s, life has never been the same
for music lovers,artists & especially, the recording 
companies.Mp3 is the latest buzzword among It circles.
what is Mp3? What makes them so special?
This article tries to dispel the cloud of mystery 
around them.



what is MP3:
MP3 stands for MPEG-I Audio Layer 3 or Motion Pictures
Experts Group Audio Layer-3.Like .jpg,.avi,.wav, 
Mp3 is a file format(way of storing data in a file)
invented by Fraunhofer Institute in Germany.The great 
feature about Mp3 & which makes it so popular,is its
ability to compress a file to 1/8th to 1/10 th of its
original size.Other conversion algorithm may achieve 
the same but they do so with a corresponding compromise
in quality.



Magic behind MP3s:
How do Mp3s achieve this amazing capability?The answer 
lies in the fact that data reduction of Mp3 file is 
based upon hearing capacity of the human ear(still,another
technology based upon Mother Nature).The Human ear
can hear(clearly) sounds within a specified range
of frequency called audible frequency.This audible 
frequency range contains a maximum frequency & a
minimum frequency(fmax & fmin respectively).
              Any sound whose frequency is greater 
than fmax or fmin is inaudible to the human ear.
Consider the following coding process used in the industry:

    

  1. Waveform Coding:
In this type of coding,decoded signal corresponds
to the input signal.It contains both audible & inaudible
frequencies increasing the size of the file.

    2. 

  2. Perceptual Coding:
In this type of coding,sound of the decoded corresponds
to the input signal.It contains only audible frequencies.
It determines which frequencies (in the file)audible to 
the human ear & obilerates the rest of them.It evaluates
the level based upon the psycho-acoustic data,which gives
special significance to the human hearing capacity.Since
this coding is based upon the perceptual property of 
the human ear,it is called perceptual coding.Since only
sounds which are inaudible are masked out,there is no 
reduction in quality,making them very efficient & compact.


The conventional wave files (.wav) & others are based upon
waveform coding whereas Mp3 files are based upon perceptual
coding.This makes Mp3 files very efficient & more importantly,
compact.



Mp3 players:
The popularity of Mp3s has spawned the production of 
Non-Portable Mp3 players (software) & Portable Mp3 players
(Hardware).

    

  1. Non-Portable Players:
These are software programs like Winamp,Music Match
Jukebox which are available for free on the net.
They can be used only in the PC's in which they
are resident.eg:Winamp,MMjp,Jetaudio...

    2. 

  2. Portable Players:
These are devices like the Walkman which are
produced by manafactures like Sony,Diamond Multimedia
for sale.The Mp3 songs are stored in the media
& are carried along.eg: Diamond Rio,Sony memory stick
walkman...



Recording companies:
The advent of Mp3 players & its like has led to increasing
audio-piracy & loss of revenue to recording companies.
The recording companies are constantly waging legal battles
against websites & players regarding audio-piracy,winning some
& losing some.The recent legal battle against Napster.com
resulted in Napster.com being closed & its founder being
jailed.



Artists & General public:
Response from artists has been contradicting.While some
bands oppose Mp3 & affliates,others (like Madonna,Public
Enemy)are in open support of Mp3s.New & budding artists 
are jubilant because they don't even require a distributor
for distributing their songs & many have achieved stardom.
           The general public have been quick in adapting
to this new culture sweeping across the globe.Portable
Mp3 players are commonplace in most developed nations & 
Non-portable players like winamp are present in every
PC.



Mp3 resources on the Net:

    

  1. www.mp3.com.
    2. 

  2. www.mpeg.org.
    3. 

  3. www.winamp.com.
    4. 
The list goes on...


As of know,MP3s rule the music world.Lets see what the 
future brings!!
                           -Shantini.R & Sangeetha.S.
                                98csesrec.


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