A little introduction to MP3s
Hello there readers. Today I present to you yet another guest post by NathanKP from Inkweaver Review – please take some time to check out his website.
What is an MP3 and how does it work?
An MP3 is a file specifically designed for storing music. The term MP3 stands for MPEG layer 3 audio, the compression algorithm that is the basis of MP3. This algorithm is what encodes music and makes it possible to put it in a file such as the MP3 format. Real music is smooth analog wave forms that come directly from an instrument. When music is stored on a CD, however, it must be in a digital format or ones and zeros. Digital formats do not tend toward the accurate presentation of wave forms, so they must be approximated by using a sample rate. A CD samples the pure analog music about 44100 times a second and uses that to create a wave that is not purely smooth, but rather like stair steps. However, the human ear can’t really hear the difference without listening very carefully and training your ear. This sample rate is a type of compression, because analog music, on an LP for example, holds an infinite amount of data in each finite time period. CD sampling reduces this “infinite” file size to a mere 10mb a minute. However, that is still much too large for ordinary purposes.
MP3 is the next level of compression, able to store music data at approximately 1mb per minute. The way it does this is by simplifying the music by purposely losing some of the sounds. For one thing most humans can only hear a specific range of frequencies, in the 20 Hz to 20 kHz range. Some animals can hear sounds higher or lower than this but humans in general can’t. By cutting out sounds outside of this narrow range MP3 can greatly reduce file size.
Secondly MP3 reduces the sampling rate so that the wave approximations in the music have even more sharp “steps.” This, however, simplifies the wave forms by removing small variations. Then the music is encoded by using mathematical formulas to pull out data about the basic shape of the wave forms that make up the music.
Every kind of wave form can be approximated by a mathematical formula. Calculus and other math techniques can be used to fit math formulas to wave shapes. The math formulas have specific formulas that require much less storage space than a complex sample of music. The MP3 software algorithm uses code called a CODEC to handle this part of the MP3 compression. The CODEC uses statistical information about the shape of the wave forms to recreate them. It is sort of like graphing a complex calculus math problem. The problem might have only a few factors in it but the shape it creates can be quite complex. In this way MP3 is able to store the complex wave forms of music very efficiently.
Of course this is a very lossy technique. Not only is the frequency limited, and the sample rate reduced, but the music sounds itself are merely a mathematical approximation. However, most people can’t really hear the difference between MP3 music and CD music, or even pure analog music of an LP.
MP3 Software
There are a plethora of different MP3 players on the market. As far as free software for computers goes the very best are VLC player, a very light player that is easy on computer resources, and WinAMP, another free MP3 player that has been around for a long time.
Note from Dion Moult: I would also like to recommend “mplayer”.
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