During the early years of the MP3 format the Fraunhofer institute released several MP3 codecs (coder/decoder) that worked as plug-ins within audio frameworks, enabling all kinds of audio processing applications (editors, recorders, transcoders, etc) to export to MP3.

These codecs were based on the FhG MP3 encoders of the time: l3enc, mp3enc, and later fastenc.

In Windows they plugged into the Audio Compression Manager (ACM) framework, meanwhile in Mac OS they were associated with QuickTime. The ACM codecs became so popular (mostly obtained from, eh... "alternative" sources) that several frontend programs were developed.

A great resource to obtain information about differences between various ACM codec versions is located at Gabriel Bouvigne's website.


This version was distributed with WMP11:
Date: 2006-04-19
Version: 3.4 (professional)
Interface: ACM codec
Platform: Win32
Bitrate range: 8-320kbps
Download: l3codecp-3.4.exe - 193kB
Kindly contributed by Zachary Jelesoff

This version was distributed with WMP10:
Date: 2005-01-28
Version: 3.3.2.44 (professional)
Interface: ACM codec
Platform: Win32
Bitrate range: 8-320kbps
Download: l3codecp-3.3.exe - 234kB

This is a pirate version that was released by the famous Radium group:
Date: 1999-06-26
Version: 1.2.63
Interface: ACM codec
Platform: Win32
Bitrate range: 8-320kbps
Download: l3codecp-radium.exe - 207kB

This version was distributed with JRiver Media Jukebox 5:
Date: 1999-01-29
Version: 1.9.0.306 (advanced)
Interface: ACM codec
Platform: Win32
Bitrate range: 8-56kbps
Download: l3codeca.exe - 258kB

This decoder-only was distributed with .mp3 Producer 2.1:
Date: 1998-04-06
Version: 1.0.0.64 (decoder)
Interface: ACM codec
Platform: Win32
Bitrate range: decode only
Download: l3codecx.exe - 228kB

This 16bit decoder-only was distributed with WMP5.2 beta for Windows 3.11:
Date: 1998-04-06
Version: 1.0.0.64 (decoder)
Interface: ACM codec
Platform: Win16
Bitrate range: decode only
Download: l3dec16.zip - 81kB

This version was distributed with MPEG Layer-3 Producer 1.1:
Date: 1997-04-07
Version: 1.0.0.48 (professional)
Interface: ACM codec
Platform: Win32
Bitrate range: 8-128kbps
Download: l3codecp-1.0.0.48.exe - 294kB

---

Date: 1999-04-16
Version: 1.5
Interface: QuickTime component
Platform: Mac OS Classic PPC
Bitrate range: 20-256kbps
Download: Fraunhofer_MP3_Codec.hqx - 1.289kB