What Exactly is an MP3?

Written by Mark Sanborn: Aug 30, 2007

An MP3 is a file format. It stands for MPEG-1 Audio Layer 3. The name is not as really important as what exactly is digital audio. Audio is nothing more than a sound wave. It has certain attributes, usually these waves go up and down, have a height and a length.

As you may know computers only communicate using 1s and 0s; therefore, in order to represent these waves on a computer we need to translate and record the attributes of these waves with 1s and 0s. Below is a picture showing how we break down the attributes of the wave into numbers on a grid.

Digital Audio Signal

The numbers are then put in a sequence and stored digitally on a computer usually as a .wav file. This file is an exact (close enough) copy or replication of the analog sound waves, hence the name .wav. Since these files have to contain every attribute of the wave they can become very large and take up a lot of drive space. This is where MP3 comes to the aid.

MP3 takes the attributes of the wav file that the human ear cannot distinguish and removes them from the .wav file. It also has a way of compressing the data using what is called lossy compression. For example you could abbreviate the word Montana with MT. As long as the person receiving the file understands that MT is an abbreviation for Montana. This is called encoding and decoding. Encoding in terms of compression is to represent data using the least amount of bits. Decoding is interpreting the bits and displaying the actual data to the end user.

To clarify Montana is encoded to MT. As you can see MT is much smaller than Montana and takes up less space but means nothing to the end user until its decoded. The decoder or codec then converts MT to Montana and you have the final result.

MP3’s specific compression methods are too complicated to go into detail but hopefully you get the idea of what encoding and decoding is along with how analog sound waves are converted to digital 1s and 0s.

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