What are MP3 files and how do they work

CDs store music using 44,100 16-bit digital samples per second, adding up to about 10 megabytes per minute -- and that's too large to move easily move across the internet. Check out this HowStuffWorks podcast to learn how MP3 files solve this problem.

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Episode Transcript

Speaker 1 (00:00):
Welcome to brain Stuff from how stuff works dot com
where smart Happens. Hi. I'm Marshall Brain with today's question,
what are MP three files and how do they work?
A CD stores music using forty four thousand, one hundred
digital samples per second, sixteen bits per sample, and two

(00:20):
channels for stereo sound. This means that a CD stores
about ten million bytes or ten megabytes of data per
minute of music on a CD. A three minute song
therefore requires thirty megabytes of data on a CD. If
you've ever tried to download files on the Internet, you
know that thirty megabytes is a big file. If you're

(00:40):
using a slow connection to connect to the Internet, thirty
megabytes of data would take several hours to download. MPEG
stands for the Moving Picture Experts Group, and they've developed
compression systems used for video data. For example, DVD movies,
h d TV broadcasts, and ds A satellite systems all

(01:01):
use MPEG compression to fit video and movie data into
smaller spaces. The MPEG compression system includes a subsystem for
compressing sound. It's called MPEG Audio Layer three, and we
know it by its abbreviation MP three. MP three can
compress a song by a factor of ten or twelve

(01:21):
and still retain something close to CD quality. So a
thirty megabytes sound file from a CD reduces to three
megabytes or so an MP three. When you download the
MP three file and play it, it sounds almost as
good as the original file. If you wanted to, you
could download an MP three file, expand it back to
its original size, and then record it on a writable

(01:43):
c D so you can play it in a CD player.
All that you're doing is converting back and forth between
different formats to make downloading easier. Do you have any
ideas or suggestions for this podcast? If so, please send
me an email at podcast at how stuff works dot com.
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