MP4 Input Plugin
This plugin decodes .MP4 and .M4A files as well as AAC, PS AAC and the newer HE ACC profile.
Spdifer is a DirectShow filter enabling media players to passthrough multi-channel sound to the digital output without any change.
Aud-X surround codec
Aud-X surround codec is recommended for use with MPEG4 (XviD/DivX) movies and it enables you to encode AC3 and WAV values.
MADFilter and Winamp MAD Plug-in
MADFilter is a DirectShow MPEG audio decoder filter, which enables its users to decode the MPEG audio format to the PCM Wave format. It comes with the Winamp MAD Plug-in.