The Fraunhofer MPEG codec is one that is needed when wanting to listen to MP3 files. The codec is norammly misisng when you get one of 2 messages : Tag 55 which means the codec is missing or Tag 85 which means the decoder is missing.

Fraunhofer MPEG Layer-3 Audio Decoder

Any of these errors tells you that you need to install the Fraunhofer MPEG codec to listen to your music.

[DefaultInstall]
SmartReboot =I
CopyFiles            = MP3.CopyCodec, MP3.CopyRegTool
AddReg               = MP3.RegNetShowCodecTable
RunPostSetupCommands = MP3.Register
EndPrompt            = MP3.EndPrompt

[DefaultInstall.NT]
SmartReboot =I
CheckAdminRights=1
CopyFiles            = MP3.CopyCodec, MP3.CopyRegTool
AddReg               = MP3.RegNetShowCodecTable
RunPostSetupCommands = MP3.Register
EndPrompt            = MP3.EndPrompt

[DestinationDirs]
MP3.CopyCodec   = 11 ; System directory
MP3.CopyRegTool = 17 ; INF Directory

[MP3.CopyCodec]
l3codecx.acm,,,0

[MP3.CopyRegTool]
regl3acm.exe,,,6 ; flag=2: no skip allowed
; flag=4: no version check

[MP3.RegNetShowCodecTable]
HKLM,”Software\Microsoft\NetShow\Player\Codecs\%CODEC_DISPLAYNAME%”,”URL”,,”%CODEC_URL%”

[MP3.EndPrompt]
Prompt=”%PROMPT_DONE%”

[MP3.Register]
%17%\regl3acm.exe l3codecx.acm

[SourceDisksNames]
1=”FHG Codec Install”,L3CODEC,

[SourceDisksFiles]
l3codecx.acm  = 1
regl3acm.exe  = 1

[Strings]
PROMPT_DONE                 = “MPEG Layer-3 audio codec installation is complete.”
ERROR_WRONG_ADVPACK_VERSION = “You need a newer version of Advpack.dll”

CODEC_DISPLAYNAME           = “MPEG Layer-3″