Friday, July 26, 2013
INTRODUCTION
Web enabled digital music entertainment system
have sent ripples across music lovers and have become very popular. To listen
to a traditional maestro, one needs not attend a concert or go to a music store
to buy cassettes or CDs. Music artisans and production companies can now host
their programs on the web. Music in the form of compressed digital files can be
distributed and delivered across the internet down to the PCs and MP3 players.
MP3 has become synonymous with the internet and is
threatening to wholly redefine the way in which people have so far been getting
and enjoying music. Its popularity is soaring, but not too many people still
know what it stands for and what it is capable of. MP3 is more about producing
high quality audio by compressing the data. MP3 has made it much easier and
faster to deliver music through the internet. Only a few years ago, downloading
a song from the net might have taken 20 minutes, but with MP3 , it takes much
less time.
WHAT
IS MP3:
MP3 stands for Motion Picture Expert Group1 Layer3
(MPEG-1 Layer 3). MPEG is a
audio-video standards setting body under the International Standards
Organization (ISO) and the International Electromechanical Commission (IEC).
MPEG layer 3 is a type of where processed by
significant compression from the original audio source with very little loss in
sound quality. The compression up to 12:1 produces very little degradation.
Tighter compression can be achieved but it results in sound degradation . to
obtain certain compression , we must adjust the bit rates. The stand art bit
rates (near CD quality) is 128 or 112 Kbps. The advantage if MP3 is that it can
be broken up to pieces and each piece is still playable. The feature that makes
this possible means that MP3 files can
be made to stream across the net real-time. The disadvantage of MP3 compression
is that lots of processor power is required to encode and play files , also a
sound card is required. The hardware player/encoder/decoder is still in
development and have very expensive price.
ORIGIN:
Invented in 1991, at the Fraunhofer Institute, a
German audio research labs, MP3 is a compression that makes files of CD-quality
sound. Enterprising college students were among MP3s earliest pioneers,
attracted by the flexibility of the format, and the great sound. With time on
their hands and fast moving T1 lines at their disposal, they turned their
computers in to virtual juke boxes makes making MP3s of live performances,
swapping music and establishing boot leg web sites.
As these early adapters have graduated in to the
real world MP3 technology has moved beyond the college-dorm circuit. At first
the record industry paid no mind to this subculture growing under its nose. But
now it became main source of music downloading by violating the copyright law
resulting in a prediction that Mp3 will spell out the end of the music
industry.
MPEG Layer3 is a specification for storing audio
information in a compressed format. Just as we use the popular PKZIP for
compressing application and data files, we have programs that compress
multimedia information. A negligible amount of compression is achieved if we
use PKZIP to compress multimedia data. This is because programs like PKZIP look
for repeating patterns of bits and bytes, and replace them with tokens to
reduce the file size. Although multimedia files, particularly music contain
repeating patterns, they are not apparent after digitization. The bits and
bytes that correspond to two different sections of music will not be identical
even if they sound the same to the human ear.
This means that to compress an audio file
effectively one needs to exploit the way humans perceive sound. Such encoding
schemes are called perpetual encoding schemes. Such encoders contain what is
called psycho acoustic model- a virtual representation of the human auditory
system. The psycho acoustic model is used to find parts of the audio, which are
not audible to the human ear owning to the auditory system’s limitations. The
encoder throws away this imperceptible audio data in such a manner as to meet
the targeted bit rate. The bit rate is the amount of compression required,
usually expressed in kilobits per second (kbps). Low bit rate means high
compression and viceversa.
There is however one major point of distinction
between a zip file and an MP3 file. When you expand a zip file you get back an
exact copy of the original with no loss of information. This is called lossless
compression. Its altogether a different story with MP3. Decompressing an MP3
file will not give you an exact copy of the original source file . Information
is irretrievably lost during the MP3 encoding process.
WHY
COMPRESSION:
A digital audio signal typically
consists of samples with a size of 16 bits. According to the sampling theorem,
at a given band width, a sample has to be taken at a rate that equals twice the
frequency of the program material. If CD quality is required in respect of
bandwidth (44.1 kHz) , then a data rate of about 1.35 Mbits/s is needed to
convey an audio signal. In other words, one minutes of music requires about
10Mbytes of data to be conveyed or stored on a data carrier. Unfortunately ,
that is not predictable even with the huge capacity of today’s hard disks.
Obviously , the resultant transmission (=
download) times using media like the Internet , Internet-Radio or Music On
Demand Systems would be very long and
hence prohibitive. In this case , the only solution is to find a way to reduce
the immense size of the relevant data, the ‘real world’ aim being to convey a
stereo music signal across an ISDN (Integrated Services Digital Network) link
with a capacity of 64Kbps per channel. In view of required compression rate of 1:12, that would
seem to be possible only if losses are accepted. Over a relatively short
period, a system called MPEG-1 layer 3
has established itself as the defacto standard for audio transmission
via the internet. MP3 employs compression algorithms that take the real life
response of human ear into account. The resultant quality of reproduced sound
is so good that even trained experts are unable to hear the difference between
a copy and its original. MP3 is also clearly superior as compared to other MPEG
layers such as the Digital Compact Cassette (MP1), Digital Audio broadcasting,
the Video-CD (MP2) and simpler systems like CELP, micro-law or ADPCM.
PSYCHO-ACOUSTICS:
The science of Psycho-Acoustics studies the
behavior of the human hearing system in relation to processing of acoustic
information in the brain. Psycho acoustic principles have been extensively used
in the development of MP3 and indeed many other compression techniques.
The audible spectrum may be thought of as
consisting of 26 frequency bands.
The frequency range below 500 Hz is subdivided
into five bands of 100Hz each. Above this range, the bandwidth is about 1/5th
of the center frequency. In the human hearing system, soft sounds become less
distinct and even inaudible when loud, discrete sound levels occur within these
‘critical’ bands. As an aside, you should note that the frequency resolving
capacity of the human hearing system is much more accurate than the critical
bands. The above phenomenon is a condition to allow masking of a soft sound by
a loud sound which occurs at a near by frequency and/or instant.
A psycho acoustic model analyses the audio signal
and employs complex algorithms ot compute the usability of masking sound in the releavant frequency rage. The closer
the model gets to reality, the higher the compression rate that can be achieved
at a given quality level of the output
signal.
HARDWARE
AND SOFTWARE:
To play back MP3 files, the recommended minimum
specification is a 486DX4, 100MHzs machine. To create your own files you need
to powerful PC- pentium 200 or above. Of course you need a sound card. A 64MB
RAM, CD/DVD drive and the internet connection to download.
Try to power the audio from batteries rather than the electricity coming from the mains.
This greatly reduces the amount of noise in the wave files as the electricity
from the mains is very noisy, electromagnetically speaking. Walkmans and other
portable audio systems make an ideal source for this reason.
To create MP3 files from music CDs one should
preferably have a sound card that
accepts digital inputs and a CD-ROM drive
that allows for DAE(Digital Audio Extraction).
HOW
TO CREATE MP3 FILES:
Audiograbber is a software that creates wave file
form audio CDs. This process of creating wave file from audio CDs is called
‘ripping’, ’white tiger’ is also software which can rip a CD and create a wave
file.
The captured wave file ideally needs to be cleaned
up quite a bit before it can be compressed to MP3. The wave format includes a
header and optionally a footer with he music contained with in. Many
applications dealing with sound do not recognize these data and instead
interpret them as audio. Thus during play back one of ears clicking or ticking
or even a popping sound. This has to be manually removed using software like
‘Cool Edit’. Cool Edit will graphically display to waveform. If you play the
wave file from cool edit a cursor will traverse across the waveform which will
enable you to locate sources of noise.
You can zoom in on selected portions of the waveform. To remove clicks and
ticks at the beginning where there is no music simply zoom into those areas,
selected the portions that contain the clicks and ticks etc and simply delete them. Alternately they can be replaced
with silence (transform -> silence).
Tape hiss and other humming sounds may exist
through out the wave file if you had powered your audio system from the
electrical mains. This is one area where cool edit really excels. To remove
these type of noises first select an area of the wave, which contains only this
type of noise.
This section should be at
least 0.5sec long. Play this section at a loud enough volume to make sure that
it contains only the noise that you wish to remove. The space between songs is
ideal for this. After selecting the area with noise use command
TANSFORM->NOISE REDUCTION you should get a dialogue box containing a button
filled get noise profile from selection. Upon clicking this button, cool edit
will generate a noise profile based on the selection. Save this noise profile.
A noise profile enables cool edit to distinguish between noise and signal
(music). Now zoom out and select the entire wavefile. With the whole wave file
selected use TANSFORM->NOISE REDUCTION and after making sure that the noise
profile saved earlier is loaded, click OK. The operation may take a long time
nearly one and half an hours for a 45-minute wave file on 450MHzs Pentium III.
Cool edit achieves noise reduction by analyzing frequencies and not amplitude.
To prevent your MP3 files from playing back at
different levels, you need to ensure that they are all recorded at the same
level. This is called ‘normalization’. Cool edits menu command is
TANSFORM->AMPLITUDE->NORMALIZE.
The final step is to encode the wave to MP3. There
are quite a few encoders available, which vary in price and quality. The
variation arises because while the MPEG standard specifies the decoding
process, the encoding process is left to the market forces to decide. The MP3
standard does include an algorithm written in pseudocode for demonstration
purposes, but the actual implementation of the encoding process is left to the
developers. Thus there are several different encoders that vary inprice and
quality. The best and the most expensive is the one developed by Fraunhofer
Institute called L3ENC. Another popular encoder is the one offered by Xing technologies . it costs much less
compared to the Fraunhofer encoder.
Generally, an encoder requires three parameters –
the simple rate , the number of channels , and the bit rate. The sample rate,
the number of samples per second in the audio file , usually 22050, 44100 or
48000. The number of channels is usually one(mono) or two(stereo). The rate
most often used for CD audio quality is 128 kbps ; however even 112 kbps will
provide the acceptable quality.
To compress a 45-minute wave file L3ENC will take more than two hours on a pentium
III 450 Mhz machine. However most other encoders like Xing and White tiger are
considerably faster , but the quality is usually inferior to that of L3ENC.
Thus , to create MP3s, start with a clean wave file remove as much noise is
possible , and then compress.
MP3
PLAYERS:
Either one can download MP3 files to the computer or play them
directly from the web sites. MP3 has made it much easier and faster to deliver
music through the Internet . Only a few years
ago, downloading a song from the net might have taken 20 minutes but with MP3 ,
it takes much less times.
There are two ways of playing back the MP3 music
files down loaded from the Internet . one can install a software decoder in the
computer and use it to play the files , or get hold of one of those cool and
trendy portable MP3 players to download and store music files from the
computer. The first option forces the user to sit near the computer in order to
listen to the downloaded music.
An MP3 player is designed to store and play music
encrypted in the MP3 format. Like a walkman it is portable. Storage capacity is
an essential feature of an MP3 player.
The player should have an at least 64Mb of memory capacity for an hour of music
play back. Portable MP3 players are available with 32/64Mb of memory on-board
,with provision to add another 16 or 32 Mb on an expansion card via a flash
card. When buying a MP3 device one should try to obtain as much on-board memory
as possible. most of the MP3 players developed have been incorporated with
software for windows-95 or windows-98. These devices are connected to the PCs
via serial/parallel ports by using universal serial bus ports , depending on
the facility provided in the brand.
·
Samsung Electronics unveiled the world’s smallest
MP3 player ‘Yepp’, on April 27,1999, at a trade exhibition held in Las Vegas.
Yepp with a basic memory of 40 Mb can store up to ten songs.
·
LG electronics has unveiled the world’s first
portable MP3 cassette player ‘Combo’.
·
‘Diamond Rio 500’, USA has a massive 64Mb of
internal memory. Apart from offering quality music for one hour , it has an
option of adding 32Mb , which gives you up to 90 minutes of uninterrupted
entertainment.
·
‘Pine DMusic’ , UK, has internal memory of 32Mb ,
and can hold about half an hour of music. A slot at the top can add another
32Mb of standard smart media, boosting the capacity to an hour.
·
Palm-sized ‘Jaz Piper’ has a 32Mb memory, boostable
up to 64Mb.It has built-in microphone , and is capable of storing over 30
minutes of CD quality MP3 encoded music . It can also store up to 250 telephone
numbers in the address book of memory.
·
Empeg, Somerset,UK, has developed the world’s first
MP3 player for a car, operating on Linux. The device fits neatly in to the dash
beard like any car stereo. It is no wider than a CD and uses a strong 220MHz
ARM processor which provides ample power for MP3 decoding, with spare capacity
to deal with future specifications.
·
Recently Shehan Information Systems, released MPMan
players .In addition to two currently available –MPMan F10 and F30 – the
company plans to release three new models next year. MPMan
from Shehan sells for around $220
per unit, AMAC plans to release a product
with the same storage capacity for around $150 soon. A 32Mb Rio is
selling for $199 in the US.
·
Digital way is also set to join the fray. It has
developed a model equipped with a digital camera module, which means that the
product can store digital pictures as well as music. It is schedule to be
released next, spring.
·
Using its caption technology, Korea media is
developing an MP3 that can also be used as a singing machine and language tutor.
INDUSTRY
OPINIONS:
With MP3, any body can make
high-fidelity music files from their CDs and post them on the net for every
body to access. As a result a large number of sites were set up on the Internet
to offer music in the MP3 format , with many of them distributing music for
free in violation of copy right laws.
To protect the interests of
record labels, the Recording Industry Association of America (RIAA) staged a
crusade against web sites that illegally distribute pirated music, shutting
down many of them. Against this back drop came the portable MP3 player. To the
association it was seen as a device which will make it even easier to exchange
illegal MP3 music. So it tried to block the introduction of the MP3 player, to
the US market. But its attempts to obtain a court injunction banning the device
backfired and instead gave it a much needed initial public relations boost.
REALITIES ABOUT MP3:
1.
MP3 is not illegal, it is simply an audio
compression format.
MP3
is an audio compression file format and by itself is not illegal or legal, but
like many technologies it can be implement for both legal and illegal uses. It
is similar to zip compression common to
most PC users. Zip files can be used to distribute copyrighted materials
illegally or for legitimate purposes. Some persons use MP3 to distribute
unlicensed music, but many use the technology for completely legal
applications.
2. MP3 is the standard for high quality music
and will soon be
every
PC
MP3 is an
open standard, meaning no one
organization controls it. On the Internet, open standards win and this
is why even without any significant corporate backing, MP3 is already the de
facto standard. There are more MP3 listeners, software programs, and hardware
devices than any other CD quality audio format in the world.
3.
MP3 gives artists and labels
freedom to market and sell their music anyway they wish.
Artists and labels can employ MP3
technology in the best way to suit their individual needs. Give away one song
to sell a CD, distribute low quality versions of songs, sell individual songs
for digital delivery, prepend an audio commercial to songs, there are limitless
possibilities for artists to explore.
4. Hundreds of companies are building businesses
around MP3
A large number of software, hardware and
content companies are building thriving
businesses around MP3.
5.
Thousands of artists are distributing
content in MP3 today.
There are
man thousands of artists already distributing their content in Mp3 format
today. Thousands sell individual songs and thousands are using MP3 to market
their work as on the Mp3 .com song selection.
6. MP3
is the most cost effective and easy way for artists to explore online music.
It costs
nothing to begin playing MP3s (simply download a free player from MP3.com).
with $20 in software ((such as Music
Match) and a modern PC, anyone can construct MP3 files from audio CDs with
a few clicks of a mouse.
7. Mp3
can be as secure as any current audio format
MP3 is simply a file compression method
which can also include any advanced technology to regulate the use of MP3
files. Technologies such as digital watermarking, preventing digital broadcasts
form being saved, restricting the playback of an audio file to one computer are
all possible and in use in MP3 applications today.
8.
Music industry is not losing billions to MP3
Press releases have
quoted losses in the billions to MP3 piracy. If CD sales are lost due to
piracy, many are sure to be made up by exposing people to more music who then
buy CDs from bands they would no t have ever heard otherwise. In reality, it’s
an impossible number to measure. The true impct of MP3 has yet to be felt on
any grand scale.
9.
Artists and labels can make money employing MP3 technology on the net.
Given the world
audience the internet provides, smaller music niches cam be successfully
identified and courted. Bands can touch a multi-million person audience at
little to no cost using areas like the MP3 artist program, mailing lists and
other online tools.
10. MP3
users should respect copyrights.
MP3 makes it a breeze
to create digital reproductions of audio works, but that does not nullify the
copyrights of the author. Audio lovers should always get author or copyright
holder’s permission before distributing content in MP3 format.
NEW TRENDS:
As if the MP3
revolution was not enough of a night ware, Napster-a music sharing software-
has created an earth quake for the $40 billion global recording industry.
California based napster on its part maintains that its software takes the
hassle out of searching for MP3s. with no more broken links, no more slow
downloading and no more busy,
disorganized FTP sites, locating and downloading music in MP3 format has become
a child’s play. Besides, it allows users to chat with each other in forums
based on music genre, lets the user keep track of this favorite MP3 libraries
for later browsing and plays MP3 files from right inside Napster server.
The concept of
napster is one step ahead of MP3. Founded by 19 year old shawn fanning and 20
year old Sean Parker, it essentially allows the users to declare a directory on
the hard disk as “public”. This is used to download MP3 files, while the client
software makes these files and other files there accessible to anyone else in
the napster site and the user’s files are available for them to download. And
this is one of the main reasons why file swapping platform as earned the wrath
of the recording industry. RIAA aha filed a law suit against Napster Inc. on
behalf of 18 powerful record firms, accusing Napster of “contributory and
Vicarious” copyright infringement.
The napster
phenomenon was possible because of t technology called ‘peer-to-peer file
sharing’, a computer jargon for people trading files with each other.
To site an
example ABC wants a copy of latest song. He logs on to napster and keys in his
request.
§ Napster connects ABC’s hard drive to the server of the central user
directory.
§ The directory displays a list of active PC users who have the
required track of the song n their computer ABC
chooses a user.
§ Link is established between ABC and the hard drive of the chosen user.
§ Files are traded without being stored on the web.
Gnutella,
touted as napster’s big brother, accomplished this file sharing task with out
the use of a central directory. Instead
of using central server to match up users. Gnutellas software connects your
hard drive to as many other gnutela users as it can find in a leb of
peer-to-peer connections, allowing each to down load information from the hard
drive of any other.
This is how
gnutella works. The first time that you wants to work on the gnutella network,
you download a special software form the gnutella website (www.gnutella.wego.com) you next type
in the net address of an established gnutella user( the directory offers a list
of addresses incase you don’t know one). Your software then transits an e-mail
like signature that announces your presence and location. Once the link with
the other PC is established, your new friend announces your presence to all the
other PCs that it encountered in previous sessions. Your information is then
stored and the next time you log on to gnutella, you automatically are a member
each time you load your (gnutella softwre, it remember your cronies and
reconnects you with all the hard drives online. These connections introduce
your hard drive to even more new users. The linkages are endless and so form a
web.
As napster
is far easier to use its popularity has been growing by leaps and bounds. It
has been the fastest growing Internet service, expanding at between five and 25
percent a day since its release last august, with down loads of client software
amounting to some 2,00,000 every day.
CONCLUSION:
Software
companies and recording industry are pushing several competing compression
formats as alternatives to MP3s. currently gaining momentum is a security
solution proposed by inter trust. The US based firms take any kind of file,
including MP3s, and locks them inside a ‘digi box’, a kind of protective
digital shell in which the ‘encrypted’ song can be posted safety on the net.
When a consumer purchases the song, he also gets a digital ‘key’ that allows
him to listen to the tune. The publisher of the song can set conditions which
the consumer must abide, thus ensuring greater control.
With the tools of MP3 piracy with in
the grasp of the average teenager the industry is also battling to stop the
music it releases on CDs form being easily converted in to MP3s. the secure
digital music initiative(SDMI) , a consortium of major music and computer
industry companies are working on ‘digital watermarking’, a strip of code
painted on every CD. Rip a CD to create an MP3 file and the water mark remains.
Make a copy of MP3 copy and file breaks. That renders the tune unplayable on
MP3 hard ware devices made by SDMI members.
BIBLIOGRAPHY
Magazines:
Information
Technology, Feb. 2000
Information
Technology, May. 2000
Electronics
for You, April. 1999
Electronics
for You, July 2000
Elecktor India, June-July 2000
