What is MP3

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M P 3
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What is MP3?

• A means of compressing digital sound files which,
  at CD quality, require some nine megabytes per
  minute.
• MP3 applies existing knowledge, about how the
  human ear and brain process auditory information,
  to achieve huge reductions in file size (factors
  of 10 to 14) with only small reductions in
  discernible sound quality.

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Digital Sound on CD

• Audio CDs are made by sampling the wave of an
  analog sound signal some 16 times a second.
• Using right angled steps between the sampling
  points, the wave is represented in saw-tooth
  form. Sine/cosine readings from the resulting
  triangles are expressed in binary code to give
  high fidelity digital representation of the wave.
  At play back, the wave is rebuilt from these
  digital blueprints.

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Digital Sound and MP3

• The process just described gives top quality
  sound, but uses around 1.4 million bits per
  second. This is taxing on secondary storage, and
  even more so on bandwidth, the major obstacle to
  a truly multi-media internet.
• Moving Pictures Experts Group (MPEG) has devised
  a set of compression formats for sound and video.
  MP3 is the most powerful format for audio, using
  algorithms that eliminate data about sound we
  dont usually perceive anyway.

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Using MP3 Files

• Play them on any PC with speakers, and a sound
  card plugged into an expansion slot on the
  motherboard.
• Decompress them and record to CD.
• For playback away from the computer, buy a
  portable MP3 player smaller, lighter, less prone
  to shock than walkmans and fewer moving parts to
  go wrong.
• Use the internet to share them with others. (Yes,
  there are legal implications more on this
  later.)

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MP3 Players

• Unfortunately the term, MP3 Player, is used to
  denote two very different things
• Software that enables MP3 files to be played on
  the computer.
• Portable hardware devices, like walkmans, that
  enable MP3 files to be played away from the
  computer

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MP3 Players (Software)

• Most of the programs currently available can be
  downloaded for free from the web, though theres
  often a charge for enhanced versions. Check these
  out
• Winamp from Nullsoft
• RealJukebox Basic from FileWorld. This also
  includes ripper software. More on this later.

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MP3 Players (Hardware)

• By downloading MP3 files from PC to player
  hardware you can listen to them in remote
  locations. Theres a lot of choice now, and you
  can spend less than 100 or well over 300.
• The market is changing constantly but limits on
  bandwidth and storage mean MP3 is likely to be
  around for quite a while yet. Before buying,
  check out thoroughly. Some of the most important
  factors are .

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Buying an MP3 Portable

• Memory - most come with 32 or 64 MB as standard.
  This will allow an hour or two of listening.
  Check out upgradability, and its cost. (Some
  players have hard disks from 300MB to 2 GB at
  time of writing - allowing days of play back
  time.)
• Connection Port - if your PC has USB (Universal
  Serial Bus) go for a USB player. Transferring
  from PC to player via the parallel port is much
  slower.
• Software is ripper software (see later)
  included? Can the player handle other compression
  formats, such as WMA?
• Other Factors much the same as for portable CD
  or cassette players eg size, weight, battery
  type, style.

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From CD to MP3

• Its simple to download software like RealJukebox
  from the web to play MP3 files on your PC (though
  how you come by them may raise big legal
  questions). And its easy to transfer them from
  PC to an MP3 player.
• But what if you want to create your own MP3
  files? This is a two step process that involves
  ripping and encoding.

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Ripping and Encoding

• Ripping is the process of extracting audio tracks
  from CDs and saving them as wave (.wav) files to
  your hard drive.
• Encoding compresses them to MP3 format. You have
  some choice over how tight the squeeze. The
  standard is 128 kbps (few can distinguish the
  results from CD quality), with 96 kbps acceptable
  to most. At 64 kbps the quality drops markedly,
  so use only when disk space is at a premium
• The freebie, RealJukebox, rips and encodes.

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Websites

• Howstuffworks for a fair overview of the
  technology
• http//www.howstuffworks.com/
• For practical help try these
• http//search.pcworld.com/query.html?qtMP3colpc
  winthe63072000rp0dtinws0qm0st1nh10o
  qrq0dtinsi0
• http//help.mp3.com/help/
• This is the most comprehensive site I have seen,
  covering legal, ethical, commercial issues as
  well as the practicalities of getting into MP3
• http//hotwired.lycos.com/webmonkey/00/31/index3a.
  html?twfrontdoor