The MP3 movement is one of the most amazing phenomena that
the music industry has ever seen. Unlike other movements --
for example, the introduction of the cassette
tape or the CD -- the MP3
movement started not with the industry itself but with a huge
audience of music lovers on the Internet.
The MP3 format for digital music has had, and will continue to
have, a huge impact on how people collect, listen to and
If you have ever wondered how MP3 files work, or if you
have heard about MP3 files and wondered how to use them
yourself, then this article is for you! In this edition of HowStuffWorks,
you will learn about the MP3 file format and how you can start
downloading, listening to and saving MP3 files onto CDs!
The MP3 Format
If you have read How CDs Work,
then you know something about how CDs store music. A CD stores
a song as digital information. The data on a CD uses an
uncompressed, high-resolution format. Here's what happens when
a CD is created:
- Music is sampled 44,100 times per second. The samples
are 2 bytes (16
- Separate samples are taken for the left and right speakers
in a stereo system.
So a CD stores a huge number of bits for each second of
44,100 samples/second * 16 bits/sample * 2 channels
= 1,411,200 bits per second
Let's break that down: 1.4 million bits per second equals
176,000 bytes per second. If an average song is three minutes
long, then the average song on a CD consumes about 32 million
bytes of space. That's a lot of space for one song, and it's
especially large when you consider that over a 56K modem, it
would take close to two hours to download that one song.
The MP3 format is a compression
system for music. The MP3 format helps reduce the number of
bytes in a song without hurting the quality of the song's
sound. The goal of the MP3 format is to compress a
CD-quality song by a factor of 10 to 14 without
noticably affecting the CD-quality sound. With MP3, a
32-megabyte (MB) song on a CD compresses down to about 3 MB.
This lets you download a song in minutes rather than hours,
and store hundreds of songs on your computer's hard
disk without taking up that much space.
Is it possible to compress a song without hurting its
quality? We use compression
algorithms for images all the time. For example, a GIF
file is a compressed image. So is a JPG file. We create Zip
files to compress text. So we are familiar with
compression algorithms for images and words and we know they
work. To make a good compression algorithm for sound, a
technique called perceptual noise shaping is used. It
is "perceptual" part because the MP3 format uses
characteristics of the human ear
to design the compression algorithm. For example:
facts like these, certain parts of a song can be eliminated
without significantly hurting the quality of the song for the
listener. Compressing the rest of the song with well-known
compression techniques shrinks the song considerably -- by a
factor of 10 at least. (If you would like to learn more about
the specific compression algorithms, see the links at the end
this article.) When you are done creating an MP3 file, what
you have is a "near CD quality" song. The MP3 version
of the song does not sound exactly the same as the original CD
song because some of it has been removed, but it's very close.
- There are certain sounds that the human ear cannot hear.
- There are certain sounds that the human ear hears much
better than others.
- If there are two sounds playing simultaneously, we hear
the louder one but cannot hear the softer one.
From this description, you can see that MP3 is nothing
magical. It is simply a file format that compresses a song
into a smaller size so it is easier to move around on the
Internet and store.
MPEG is the
acronym for Moving Picture Experts Group. This
group has developed compression systems used for video
data. For example, DVD
broadcasts and DSS satellite
systems use MPEG compression to fit video and movie
data into smaller spaces. The MPEG compression system
includes a subsystem to compress sound, called MPEG
audio Layer-3. We know it by its abbreviation,
Using the MP3 Format
Knowing about the MP3
format isn't half as interesting as using it. The MP3 movement
-- consisting of the MP3 format and the Web's ability to
advertise and distribute MP3 files -- has done several things
- It has made it easy for anyone to distribute music at
nearly no cost (or for
- It has made it easy for anyone to find music and access
- It has taught people a great deal about manipulating
sound on a computer.
Technology has made it easier to download and
play your favorite
That third one was accidental but important. A big part of
the MP3 movement is the fact that it has brought an incredible
array of powerful tools to desktop
computers and given people a reason to learn how they
work. Because of these tools, it is now extremely easy for you
all of these amazing things, all you need is a computer with a
card and speakers,
an Internet connection, a CD-R
drive to create CDs and an MP3
player. If you simply want to download MP3 files from the
Web and listen to them, then all you need is a computer with a
sound card and speakers and an Internet connection -- things
you probably already have!
- Download an MP3 file from a Web site and play it
- Rip a song from a music CD and play it directly or
encode it as an MP3 file
- Record a song yourself, convert it to an MP3 file and
make it available to the world
- Convert MP3 files into CD files and create your own
audio CDs from MP3 files on the Web
- Rip songs off of various music CDs and recombine them
into your own custom CDs
- Store hundreds of MP3 files on data CDs
- Load MP3 files into tiny portable
players and listen to them wherever you go
Let's look at many of the different things you can do with
MP3 files and the software that makes it possible.
Downloading and Listening
If you would like
to download and then listen to MP3 files on your computer,
then you need:
If you have
recently purchased a new computer, chances are it already has
software that can play MP3 files installed on its hard disk.
The easiest way to find out if you already have an MP3 player
installed is to download an MP3 file and try to double-click
on it. If it plays, you are set. If not, you need to download
a player, which is very easy to do.
- A computer
- A sound
card and speakers
for the computer (If your computer has speakers, it has a
- An Internet connection (If you are browsing the
Web to read this article, then you have an Internet
connection and it is working fine.)
- An MP3 player (a software application you can
download from the Web in 10 minutes)
There are literally thousands of sites on the Web where you
can download MP3 files. Here are three of the biggest:
one of these sites, find a song and download it to your hard
disk (most MP3 sites let you either listen to the song as a
streaming file or download it -- you want to download). Most
songs range between 2 and 4 MB, so it will take 10 to 15
minutes unless you have a high-speed Internet connection. Once
the song has finished downloading, try to double-click on the
file and see what happens. If your computer plays it, then you
If you find that you cannot play it, then you need to
download an MP3 player. There are dozens of players
available, and most of them are free or shareware (shareware
is extremely inexpensive). One of the most popular is WinAmp,
which you can download from http://www.howstuffworks.com/framed.htm?parent=mp3.htm&url=http://www.winamp.com.
For a complete list of all of the available players, check out
page from MP3.com. Once you download and install a player,
double-click on the MP3 file that you downloaded and it will
You are now ready to begin collecting MP3 files and saving
them on your computer. Many people have hundreds of songs they
have collected, and they create jukebox-like playlists so that
their computer can play them all day long!
Taking the Files With
Many people who start collecting MP3 files find
that they want to listen to them in all kinds of places.
MP3 players answer this need. These players are like
portable cassette players except that they are smaller.
These players plug into your computer's parallel
or USB port
to transfer the data, and a software application lets you
transfer your MP3s into the player by simply dragging the
files. See How MP3
Players Work for details.
Creating Your Own
If you have a CD
collection and would like to convert songs from your CDs into
MP3 files, you can use ripper and encoder
software to do just that. A ripper copies the song's
file from the CD onto your hard disk. The encoder
compresses the song into the MP3 format. By encoding
songs, you can play them on your computer or take them with
you on your MP3 player.
is a popular ripper/encoder that you can use to do the job. This
page from MP3.com contains an extensive list of other
rippers and encoders.
Writing MP3s to CDs
you have a writable CD
drive in your computer, there are two ways to save your
MP3 files on a CD:
WinAmp has a plug-in that creates full-size WAV
files from MP3 files, and some of the encoders will also
decode. Once you have the full-size CD tracks, then the
software that comes with your CD-R
drive will let you create an audio CD easily.
- You can write the MP3 files themselves onto a data
CD in order to save them and clear some space on your
hard disk. You can then listen to the files on any computer.
- You can convert (decode) your MP3 files into full-size
CD tracks and then save them to an audio CD. This
allows you to listen to your MP3 files on any CD player.
FAQ is an excellent source of information on getting data
and music onto a CD.
Distributing Original Music
If you are an
artist who is recording music at home or in a small studio,
you can use MP3 files and the Web to distribute your music to
an extremely large audience. The first step is to create a
song, either on a cassette
or CD. If it
is on a CD, you can use the ripper and encoder tools described
in the previous section to create an MP3 file. If it is on a
cassette (or minidisc), you can connect the output of your
cassette (or minidisc) deck to the line-in or microphone
jack of your sound card and record the music digitally on your
computer. Then you can encode that file to create the MP3.
Once you have an MP3 file in hand, you have two
One good option is to make your MP3 files
available on MP3.com and then link to the MP3.com download
area from your band's Web site. This lets you get the best of
both worlds, and you can take advantage of MP3.com's servers
for the large MP3 files.
- You can go to a site like MP3.com
and let them distribute your music. The advantage of this
approach is that MP3.com gets millions of visitors every
month, so the potential audience you can reach is very
large. To sign up with MP3.com, go to the New
Artists area. You will need at least one MP3 file, a
photograph of your band and/or album cover and some
information about the band in order to sign up. The process
is simple. MP3.com has other programs for artists as well.
- You can create your own Web site for your music or band
and promote the site yourself. This gives you more control
and individuality, but requires you to get the word out on
your own. See How Web
Pages Work for details on creating and hosting your own
For more information on the MP3 format, MP3 sites and
related topics, check out the links on the next page.
Lots More Information!
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