The mp3 music file format revolutionized digital music distribution in the late 1990s, allowing people to trade music files over the Internet and onto portable MP3 players. Before that, music was stored on analog formats like CDs and tapes. Analog formats store sound as an electrical signal that corresponds to a mechanical displacement of a speaker diaphragm. The MP3 file format stores sounds as a sequence of numbers, but when it’s played back, an electronic circuit converts those numbers back into an analog electrical signal that’s then fed into a speaker and heard as a sound wave.
A computer analyzes the volume and frequency of each sound as it’s recorded on a CD or in an MP3 file. It records the sounds as binary data, which are 0s and 1s, essentially a series of on and off values. Then, a process called “perceptual encoding” looks at the recorded data and drops those bits representing sounds that are outside the range of human hearing. So, an MP3 file with 100kb of data might have a five-minute song, but it would only be able to reproduce the sounds from the first three seconds because the rest of the information is inaudible.
MP3 Music: Everything You Need to Know About Digital Downloads
Some sound quality experts say that this compression technique can result in audible artifacts, but most listeners cannot detect the artifacts when listening to a well-made mp3 file at a high bit rate (e.g., 128 kbps CBR). The best MP3 encoders are very sophisticated and do a very good job of avoiding these artifacts.
When a person creates an MP3 file, they choose the bit rate, or how many kilobits per second of audio are desired. The higher the bit rate, the better the quality of the recording, but it also takes up more storage space on a hard disk or memory card.
Some MP3s are copy-protected, which means that only those who pay for a subscription to use a service like Rhapsody or iTunes can play the songs. Others are unprotected, which makes them available on sites that charge a one-time fee to download the songs. Some of these unprotected files are offered by record companies and artists to give their fans the option of buying high-quality MP3s. Others are offered by record companies to promote their albums or other content. Most of these unprotected mp3s can be converted to high-quality versions using programs that remove any digital rights management protections. These programs will usually allow the user to choose from a variety of different encoding settings, which may result in an even smaller mp3 file size. However, these programs are often not very easy to use or have limited features. In addition, some of these mp3 conversion programs can only handle one type of mp3 file at a time, and do not support any lossless mp3 formats.