Back in 1995, when hard disk capacity and internet bandwidth were at a very great premium (modems rarely went beyond 28 kbps, and a CD could hold two medium hard drives), an audio format that could turn a massive file into a very small file was obviously the best choice to save your songs. As a result, a medium-quality song encoded into MP3 takes up very little space - usually 4 MB note A 4-minute song on 128 kbps MP3, very close to CD-quality audio, weighs in at 3.75 MB 192 kbps, which takes a trained ear to distinguish from CD audio, is only half again as large, much less than the 30-60 MB they usually take on a CD. Thanks to its psychoacoustic model, MP3-encoding can strip a lot of this information from the audio, and yet it still sounds pretty much the same as the original source to most people. You know all the pianos and clarinets and timpanis and stuff that aren't being used by this song? MP3 leaves 'em behind. So, to continue the analogy started on their pages: if a MIDI file is just sheet music, a WAV file is an entire orchestra, an MP3 is half an orchestra. This is why you can't seem to hear anything when you record a video in a classroom: your mind filters out the classroom's chatter and lets you focus on your friend's voice, but the microphone can't do this, and just picks up all the environmental sound, allowing more precise representation of the frequencies that are not dropped. Basically, this means we don't hear a soundwave exactly as it comes out of an audio source: our ear is much more sensitive to medium-frequency sounds than it is to bass and treble sounds, and our mind subconsciously filters out the background noise and amplifies the ones we want to hear. This is due to something known as psychoacoustics. However, there's one difference between MP3 and the other formats of the day: The part that removes information from the sound sequence was specially designed to remove only the sounds the human ear and brain can't hear. So far, nothing unusual: There's many other lossy audio compression techniques out there, and many of them already existed in 1994, when the MP3 format was released. In English: MP3 is a list of step by step instructions that can be followed by a computer program (algorithm) that takes an uncompressed audio file, typically of the same format used in an audio CD, cuts the waveform into about 40 split-second snippets for each second, calculates the frequency components of each snippet (the frequency domain), uses these components to remove parts of the information contained in the sequence (some information is lost in the process - hence lossy), rounds up the frequency components to some pre-defined values (quantizes them), and encodes the resulting information in a way that takes up less space than the original audio file (compresses it). The name is short for MPEG-1 Audio Layer 3, where MPEG note Motion Pictures Expert Group is a group of companies developing these sorts of audio and video compression methods. MP3, more than a simple audio format, is a lossy, frequency-domain, quantized audio compression algorithm.
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We see it everywhere on the Internet, our portable music players use MP3 audio instead of those good ol' cassettes, all phones can play audio encoded in the MP3 format, the street dealers from around the block probably sell DVDs packed with songs in MP3, and your car's sound system can probably play MP3s from your iPod, CD, or a USB drive. Unless you've been living away from civilization (or unless you're an old man who steadfastly believes Computers Are Bad, in which case, what are you doing here of all places?), chances are you've at least heard about MP3. But before you do that, please fix the link you came from. For the video games, see Mario Party 3, Metroid Prime 3: Corruption, or Max Payne 3.
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