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Speaker 1: Welcome to brain Stuff from how stuff works dot com

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Speaker 1: where smart Happens. Hi. I'm Marshall Brain with today's question,

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Speaker 1: what are MP three files and how do they work?

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Speaker 1: A CD stores music using forty four thousand, one hundred

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Speaker 1: digital samples per second, sixteen bits per sample, and two

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Speaker 1: channels for stereo sound. This means that a CD stores

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Speaker 1: about ten million bytes or ten megabytes of data per

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Speaker 1: minute of music on a CD. A three minute song

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Speaker 1: therefore requires thirty megabytes of data on a CD. If

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Speaker 1: you've ever tried to download files on the Internet, you

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Speaker 1: know that thirty megabytes is a big file. If you're

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Speaker 1: using a slow connection to connect to the Internet, thirty

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Speaker 1: megabytes of data would take several hours to download. MPEG

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Speaker 1: stands for the Moving Picture Experts Group, and they've developed

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Speaker 1: compression systems used for video data. For example, DVD movies,

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Speaker 1: h d TV broadcasts, and ds A satellite systems all

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Speaker 1: use MPEG compression to fit video and movie data into

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Speaker 1: smaller spaces. The MPEG compression system includes a subsystem for

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Speaker 1: compressing sound. It's called MPEG Audio Layer three, and we

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Speaker 1: know it by its abbreviation MP three. MP three can

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Speaker 1: compress a song by a factor of ten or twelve

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Speaker 1: and still retain something close to CD quality. So a

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Speaker 1: thirty megabytes sound file from a CD reduces to three

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Speaker 1: megabytes or so an MP three. When you download the

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Speaker 1: MP three file and play it, it sounds almost as

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Speaker 1: good as the original file. If you wanted to, you

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Speaker 1: could download an MP three file, expand it back to

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Speaker 1: its original size, and then record it on a writable

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Speaker 1: c D so you can play it in a CD player.

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Speaker 1: All that you're doing is converting back and forth between

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Speaker 1: different formats to make downloading easier. Do you have any

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Speaker 1: ideas or suggestions for this podcast? If so, please send

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Speaker 1: me an email at podcast at how stuff works dot com.

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Speaker 1: For more on this and thousands of other topics, go

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Speaker 1: to houstaff works dot com