MPEG-1 Audio Layer I

MPEG-1 Audio Layer I
Filename extension
.mp1
Internet media type
audio/mpeg, audio/MPA
Initial releaseDecember 6, 1991; 34 years ago (1991-12-06)
Latest release
ISO/IEC 13818-3:1998
April 1998; 28 years ago (1998-04)
Type of formatLossy audio
Contained byMPEG-ES
StandardISO/IEC 11172-3,
ISO/IEC 13818-3
Open format?Yes
Free format?Expired patents
Websitehttp://mpeg.chiariglione.org/standards/mpeg-1/audio

MP1 (formally MPEG-1 Audio Layer I or MPEG-2 Audio Layer I) is a lossy audio codec and one of three audio formats included in the MPEG-1 standard. For files only containing MP1 audio, the file extension .mp1 is used.

It is a deliberately simplified version of MPEG-1 Audio Layer II, created for applications where lower compression efficiency could be tolerated in return for a less complex algorithm that could be executed with simpler hardware requirements. While supported by most media players, the codec is considered largely obsolete due to wider acceptance of the more complex MPEG-1 Audio Layer II (MP2) and MPEG-1 Audio Layer III (MP3) codecs.

A limited version of MPEG-1 Audio Layer I was used by the Digital Compact Cassette format, in the form of the PASC (Precision Adaptive Subband Coding) audio compression codec. PASC and MPEG-1 Audio Layer I were essentially identical, except:

Specification

MPEG-1 Audio Layer I is defined in ISO/IEC 11172-3, the first version of which was published in 1993.

An extension has been provided in MPEG-2 Audio Layer I and is defined in ISO/IEC 13818-3, which first version was published in 1995.

MP1 uses a comparatively simple sub-band coding, using 32 sub-bands.

References

  1. ↑ M. Nilsson (November 2000). The audio/mpeg Media Type. Network Working Group. doi:10.17487/RFC3003. RFC 3003. Proposed Standard.
  2. ↑ S. Casner; P. Hoschka (July 2003). MIME Type Registration of RTP Payload Formats. Network Working Group. doi:10.17487/RFC3555. RFC 3555. Obsolete. Obsoleted by RFC 4855 and 4856. Updated by RFC 3625 and 4629.
  3. ↑ Patel K, Smith BC, Rowe LA (1993-09-01). "Performance of a software MPEG video decoder". Proceedings of the first ACM international conference on Multimedia - MULTIMEDIA '93. ACM Multimedia. New York City: Association for Computing Machinery. pp. 75–82. doi:10.1145/166266.166274. ISBN 978-0-89791-596-0. S2CID 3773268. Reference 3 in the paper is to Committee Draft of Standard ISO/IEC 11172, December 6, 1991.
  4. ↑ "ISO/IEC 11172-3:1993 - Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbit/s -- Part 3: Audio". ISO. 1993. Retrieved 2010-07-14.
  5. ↑ "ISO/IEC 13818-3:1995 - Information technology -- Generic coding of moving pictures and associated audio information -- Part 3: Audio". ISO. 1995. Retrieved 2010-07-14.
  6. ↑ "Philips DCC System Description Draft". Archive.org. Philips Consumer Electronics B.V. September 1994. Retrieved 14 April 2021. The padding bit [...] indicates whether the current frame has a 'dummy' slot
  7. 1 2 "MPEG Audio Frame Header". 2003-08-03. Archived from the original on 2015-02-08. Retrieved 2009-05-29.
  8. ↑ "MPEG-1 audio layer 1". TheFreeDictionary.com.