Fraunhofer l3enc was the first MP3 (back then called MPEG layer 3, that's why l3enc) software encoder. The first public version was released on 1994-07-13, and before that only very expensive hardware encoders existed (not that l3enc wasn't expensive itself, registration for version 2.0 cost 350DM - ~U$250)

Also, it was truly multiplatform: It ran on MS DOS (x86), Linux (x86), Solaris (SPARC), SunOS (SPARC), Irix (MIPS), NeXT (68K). The first (pre-1.0) DOS versions even featured fixed point math encoder and decoder for the 8088 architecture.

The MP3 page at Fraunhofer IIS is located here

Fraunhofer distributed, together with l3enc, an MPEG layer3 FAQ and a small collection of test bitstreams (1370Kb).

By the end of 1997 l3enc stopped being developed in favour of the development of MP3enc.


*****The First Ever publicly available MP3 Software Encoder*****
Date: 1994-03-16
Version: 0.99a
Interface: Command Line
Platform: DOS
Download: l3enc099a.zip - 311Kb


Date: 1997-12-05
Version: 2.72
Interface: Command Line
Platform: DOS
Download: l3enc272.zip - 564Kb

Platform: Linux x86
Download: l3enc272.linux.tar.gz - 206Kb

Platform: NeXTstep
Download: l3enc272.next.tar.gz - 749Kb

Platform: SGI Irix
Download: l3enc272.sgi.tar.gz - 359Kb

Platform: Solaris SPARC
Download: l3enc272.solaris.tar.gz - 236Kb

Platform: SunOS
Download: l3enc272.sun4.tar.gz - 284Kb


Date: 1997-08-27
Version: 2.71
Interface: Command Line
Platform: DOS
Download: l3enc271.zip - 294Kb


Date: 1996-11-07
Version: 2.61
Interface: Command Line
Platform: DOS
Download: l3enc261.zip - 301Kb


Date: 1996-07-31
Version: 2.60
Interface: Command Line
Platform: DOS
Download: l3enc260.zip - 312Kb

Platform: Linux
Download: l3enc260.linux.tar.gz - 198Kb


Date: 1995-09-04
Version: 2.00
Interface: Command Line
Platform: DOS
Download: l3enc200.zip - 287Kb

Platform: NeXTstep
Download: l3enc200.next.tar.gz - 686Kb

Platform: Linux
Download: l3enc200.linux.tar.gz - 179Kb


Date: 1995-02-22
Version: 1.50
Interface: Command Line
Platform: DOS
Download: l3enc150.zip - 1011Kb


Date: 1994-07-13
Version: 1.00
Interface: Command Line
Platform: DOS
Download: l3enc100.zip - 126Kb

Platform: SunOS
Download: l3enc100.sun4.tar.z - 394Kb


Date: 1994-06-13
Version: 0.99c
Interface: Command Line
Platform: DOS
Download: l3enc099c.zip - 312Kb

Platform: SunOS
Download: l3enc099c.sun4.tar.z - 284Kb