MP3 compression works by reducing (or approximating) the accuracy of certain components of sound that are considered (by psychoacoustic analysis) to be beyond the hearing capabilities of most humans.

This method is commonly referred to as perceptual coding or as psychoacoustic modeling. The remaining audio information is then recorded in a space-efficient manner, using MDCT and FFT algorithms. For example, an MP3 encoded at a constant bitrate of 128 kbit/s would result in a file approximately 9% of the size of the original CD audio.Ĭompared to CD-quality digital audio, MP3 compression can commonly achieve a 75 to 95% reduction in size. In the early 2000s, compact disc players increasingly adopted support for playback of MP3 files on data CDs. The Moving Picture Experts Group (MPEG) designed MP3 as part of its MPEG-1, and later MPEG-2, standards. MPEG-1 Audio (MPEG-1 Part 3), which included MPEG-1 Audio Layer I, II and III, was approved as a committee draft for an ISO/ IEC standard in 1991, finalised in 1992, and published in 1993 as ISO/IEC 11172-3:1993. It requires only minimal modifications to existing MPEG-1 decoders (recognition of the MPEG-2 bit in the header and addition of the new lower sample and bit rates).įurther information: Linear predictive coding and Modified discrete cosine transform An MPEG-2 Audio (MPEG-2 Part 3) extension with lower sample- and bit-rates was published in 1995 as ISO/IEC 13818-3:1995. The MP3 lossy audio-data compression algorithm takes advantage of a perceptual limitation of human hearing called auditory masking. Mayer reported that a tone could be rendered inaudible by another tone of lower frequency.

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