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MPEG Audio Layer-3

lastmod 2018-08-17created 2014-03-203 edits

MP3 (pronounced "em-pi-sseuri" or "em-pi-seuri" in Korean, MPEG Audio Layer-3, North Korean standard language (Munhwaŏ): "em-pi-sam") is a lossy compression format developed as the audio standard of MPEG-1. Created by improving on MP1 and MP2, it is regarded as the most popular music file format. It can compress PCM audio, such as from computer discs, to generally listenable quality and reduce its size to as little as 1/10. It was developed in 1987 at the Fraunhofer Institute for Integrated Circuits in Germany, together with AT&T Bell Labs and Thomson. MPEG-2 also has Audio Layer-3, which is called MP3, but its official name is MPEG-2 AudioBC (Backward Compatible). MPEG-2 MP3 uses the same compression method but adds low fixed bit rates for low-bit-rate media and multichannel support. This format is used in European DVDs. There is also something called MPEG2.5 Audio Layer 3, which is not an ISO standard.

Overview

MP3 is a lossy audio compression format. MP3 re-represents PCM audio data by discarding the parts that are not important to human hearing. (It is similar to the lossy compression technique of JPEG images.) Most of the technology used in MP3 lies in deciding, based on psychoacoustics, which parts of the audio data to discard. MP3 audio is compressed at different bitrates. Data size and sound quality are related. In other words, as data size increases, sound quality improves, whereas as data size decreases, sound quality and performance drop. MP3PRO is an improved version of MP3 made by Coding Technologies in 2003, when portable devices were popular, designed to fit many songs into a small capacity. With SBR technology, it delivers better sound quality at 64Kbps than at 128Kbps. It supports up to 256Kbps and solves the sound quality problem at low KB that was a problem with existing MP3. However, if you use a regular MP3 decoder instead of a dedicated MP3PRO decoder, the SBR-encoded part cannot be decoded, so it is decoded at 128Kbps 24Khz and sound quality drops. MP3 Surround is a version of the format introduced in December 2004 that supports 5.1 channels for surround sound. MP3 Surround is compatible with standard stereo MP3, the latter half, and mono. Its file size is also similar. MP3HD is a lossless format.

See also

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MP3 File Format

References

  1. MPEG1_Audio_Layer3_-_mp3_file_structure.pdf ↩

  2. Copy: http://ospace.tistory.com/101 & http://bhnbhn.tistory.com/274 ↩

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