Transcript How Do MP3’s Work? - 6th Grade Science :: Home

How Do MP3’s Work?
By Virginia Ellis
2004
History Of MP3
1985
2004
1989
1990
1997
1999
•Started in the mid 1980’s at Fraunhofer
Institute in Germany where they began
developing a high quality, low bit-rate audio
format
•1989 they were granted a permit for the
MP3 compression format
•Fraunhofer developed the first MP3 player
in the early 1990’s
History
• 1997 a developer at
Advanced Multimedia
Products created the
AMP mp3 playback engine,
which was regarded as the
first mainstream machine
• MP3 craze started with many types of
software available:MP3 encoders, CD rippers,
Mp3 players
History
• 1999 the first P2P (peer-to-peer) file sharing
software application released, Napster by a
university student has greatly effected the
music industry
Napster
relaunched!
Legal and easy
to use!
One of the
most
famous P2P
sharing sites
What is MP3?
•MP3 is a form of compression, stores
sound in microchips instead of a disk
or tape
•Stands for MPEG Audio Layer Moving
Picture Experts’ Group developed by
the Fraunhofer Institute
What is MP3?
•MP3 files can be compressed at
different rates, higher ratio of 10:1 is
equal to about 1 MB for each minute of
an MP3 song
•Fraunhofer has a license on MP3 that if
anyone else wants to develop further
technology they have to ask them first
before making it
A Dummies guide to MP3 Words
•Bit rate-name given to the
amount of data an application
handles per second, Mp3 with
high bit rate has excellent
sound reproduction
•Burn-given to the process of
recording a CD
•byte-eight bit string of
information
Glossary Continued
•Decoder-a software or device that can
change one file format back to another, MP3
to AIFF
•Gigabyte-(GB)equal to 1,024 MB
•MIDI-known as Musical Instrument Digital
Interface which is the format by which music
is generated by the interface of synthesizers
and computers together
How Do MP3’s Work?
•Variety of compression levels, the higher
the k-bit the better quality of sound
•Legal to rip MP3 tracks from CD for only
personal use
•Ripper copies the song’s file from hard disk
•Encoder gets the music into the MP3
format (compression) so you can listen to it
on your player
The 2 Main Tools
The ripper gets music
from somewhere else
(ex. CD to MP3)and
downloads it into your
data.
The encoder,the
key tool used with
MP3s. This gets it
into the right format
The Process of Compression
The encoding tools-rippers and encoders!
1. Encoder analyzes incoming signal
determining the “spectral energy”, and breaks it
down into a mathematical patterns, and
compares it with psychoacoustic models stored
in the encoder itself
2.Encoder can then discard most of the data.
The person encoding can specify how many bits
can be alloted to storing each second of music.
More discarded the worse the music!
Process of Compression
3.Goes through a second stage of
compression, the “Huffman Coding” which
shrinks the remaining data in the traditional zip
way! MP3 files have frames like a film strip.
They have headers and labels in them
sometimes telling what they are.
4. The frames are assembled into a serial
bitstream
MP3 uses 2 compression techniques to
achieve the best audio and throws away
inaudible sound by humans
How is compression possible?
•The size is reduced so the higher
frequency is taken out
•Irrelevant data is removed from the audio
bit stream
•Increase the bit rate for better quality
Psychoacoustics
A lot is known about it, described
accurately in tables, charts, and in
mathematical models representing
human hearing patterns. This is the range
of possible human hearing Hz.
What is Psychoacoustics?
•Uncompressed audio (found on CDs), stores
more data than your brain can actually
process
•For example if 2 notes are similar and very
close together, brain might perceive only
one
•If 2 sounds are very different but one is
much louder than the other brain might
perceive the quieter one
The Algorithm
The algorithm
helps divide the
MP3 file into sub
bands for the most
optimal result
Fi-lossy is one form
of compression
where some of the
data is lost.
How Transferring Works
•Download songs off a
legal site to avoid piracy
•Make a playlist or mix of
your music
•Plug the player into computer’s parallel or
USB Port (shown above) with a link
•Transfer files
Advantages of MP3 players
to CD players
ƘTakes up less file space than the CD
format WAV/AIFF
ƘYou can access legal downloads and get
them onto your mp3 player faster, and
more music!
ƘHas no moving parts, so it won’t wear out
like a CD player will
The iPod
iPod memory/price.
Also available in
mini for much less $!
iPods are a big part
of music culture
these days. You can
go anywhere with
them!
Cutting Edge Technology
The iPOD
•Lighter than 2 CDs, can hold 10,000 songs!
•iTunes music store and purchase songs for
about 99 cents each
•Offers high speed of transfer from an album
to your computer
•Supports popular audio formats with smaller
size so you can fit more songs!
Next Generation of the
Music Business?
•Millions of songs are shared
everyday by millions of
users
Dell MP3 player •MP3 technology is
constantly advancing
•With shareware people can
trade music with others and
Less CD buying people will not buy as
many CDs from the store
Common Misconceptions
•False:That MP3s are the
players, not true. They are file
formats!
•False:All MP3 file sharing is
illegal. In fact there is software
that is legal and even faster
than other file formats.
•True:Its the best way to carry
your music with you!
Bibliography
•Brain, Marshall; Tyson, Jeff; Freudenrich,
Craig C. “How MP3 Players Work.” How
Stuff Works. 6 May 2004. <http://www.
electronics.howstuffworks. com/mp3player3.htm
•Hacker, Scot. “MP3:The Definitive Guide.” 18
May 2004. <http://www.oreilly.com/
catalog/mp3/chapter/ch02.html>.
•Nijmeh, Gabriel. “Behind the Files:History
of MP3.” 26 April 2004.<http:// kosmoi.
com/computer/software/mp3/>.
About the Author
Hi, my name is
Virginia Ellis. I enjoy
swimming, soccer,
field hockey,sailing,
crafty junk, and
hanging out w/ my
homies and chicas.
maybe I’ll get an MP3
player next Christmas!
A golden mini iPod.
Hot stuff!
Bibliography
•Unknown Author. “What is MP3, how
does it work, what is MPEG.” MP3 For
Mac. 26 April 2004. <http://www.mp3
-mac.com/Pages/ what_is_MP3.html>.
•Unknown Author. “Apple iPod.” Gizmo
Highway. 26 April 2004. <http://www.
gizmohighway.com/personal tech/
ipod.htm>.
THE END