MP3

MP3 (formally MPEG-1 Audio Layer III or MPEG-2 Audio Layer III) is an audio coding format developed largely by the Fraunhofer Society in Germany under the lead of Karlheinz Brandenburg. It was designed to greatly reduce the amount of data required to represent audio, yet still sound like a faithful reproduction of the original uncompressed audio to most listeners. For example, compared to CD-quality digital audio, MP3 compression can commonly achieve a 75–95% reduction in size, depending on the bit rate.

MP3 became very popular in the late 1990s because it allowed people to share music easily over the Internet. This was especially important at a time when bandwidth and storage space were still limited. Many people used services like MP3.com and Napster to share music, which led to discussions about copyright infringement and music piracy.

Today, MP3 remains a widely used standard for digital audio. Even though newer formats have been created, such as AAC, most devices, including portable media players and smartphones, can still play MP3 files. The ability to store music in a small size without losing too much quality made MP3 an important part of how we enjoy music and other audio today.

History

The Moving Picture Experts Group (MPEG) designed MP3 as part of its MPEG-1, and later MPEG-2, standards. MPEG-1 Audio was approved in 1991 and published in 1993. MPEG-2 Audio was published in 1995, adding lower sample and bit rates.

MP3 uses a method called lossy compression that takes advantage of how human ears hear sound. This makes it possible to greatly reduce the size of audio files while still sounding good to most listeners. For example, MP3 files are often much smaller than CD-quality audio files.

The development of MP3 involved many researchers and institutions. Key contributors included the Fraunhofer Society in Germany, where Karlheinz Brandenburg led much of the work. Early versions of MP3 were tested using songs like "Tom's Diner" by Suzanne Vega to ensure the compression sounded natural.

In the 1990s, MP3 files became very popular on the internet. People could easily share music files with friends, though this sometimes led to debates about copyright. Today, MP3 remains a widely used format for storing and playing digital audio.

Design

MP3 is a way to make audio files smaller while keeping most of the sound quality. It works by removing parts of the sound that most people can't hear. This lets MP3 files be much smaller than regular audio files, like those on CDs.

MP3 files are made up of small pieces called frames. Each frame has a header and data that contains the audio information. There are also tags in MP3 files that hold extra information like the song title or artist. The quality of an MP3 file can change depending on how much data is used, called the bit rate. Higher bit rates usually sound better but take up more space.

Licensing, ownership, and legislation

The technology used to create and play MP3 files was once protected by patents, which are special rights that let inventors control how their inventions are used. This caused some confusion in the early days of MP3, especially in places that allow software patents. However, most of these patents have now expired.

In many countries, the key patents for MP3 expired by December 2012. In the United States, the last major patent expired on April 16, 2017. This means that today, creating and using MP3 files does not require paying for special permissions in most places. Some companies, like Technicolor, used to manage licenses for MP3 patents, but this is less common now. As a result, many free software projects now include MP3 support without needing extra downloads.

Alternative technologies

Main article: List of codecs

There are other ways to compress sound files besides MP3. One common format is Advanced Audio Coding, or AAC, which was made to replace MP3 and works even better at making files smaller. Other formats like mp3PRO and MP2 are also related to MP3.

Some companies made their own formats. For example, Microsoft created Windows Media Audio, and Sony used a format called ATRAC for its MiniDisc players before later adding MP3 support.

There are also free formats anyone can use, like Opus and Vorbis (OGG). And for those who want the highest quality sound without losing any details, there are lossless formats such as FLAC and Apple Lossless. These keep every part of the original sound but make files larger.