MP1

MPEG-1 Audio Layer I (MP1), is a lossy data compression format for audio. It is a deliberately simplified version of the MP2 file, but both formats have been largely made obsolete in favour of the more popular and higher quality MP3.

MPEG-1 Audio Layer I

Filename extension	.mp1
Internet media type	audio/mpeg,[1] audio/MPA[2]
Initial release	December 6, 1991; 34 years ago (1991-12-06)[3]
Latest release	ISO/IEC 13818-3:1998 (April 1998; 27 years ago (1998-04))
Type of format	Lossy audio