Author: Alexander Vigovsky
https://ac3filter.net/
License: Freeware
Requires: Win7/Vista/2K/XP

AC3Filter is a high quality free audio decoder and processor filter. It allows media players to playback movies with AC3 and DTS audio tracks. Also it can process any audio track, much of processing options allows to adjust the sound in almost any way. It is possible to upmix any audio source to 6 channels. Filter can do multi-channel and digital (SPDIF) output. It can encode any audio source to AC3 on-the-fly and send it over SPDIF to the receiver.

https://www.ryanvm.net/forum/viewtopic.php?t=9681