AC3Filter

AC3Filter is a free DirectShow filter for real time audio decoding and processing. It can decode the audio formats AC3, DTS, and MPEG Multichannel.

Features
Features include:
 * Playback of video with DTS and AC3 audio tracks,
 * Up-mix of any audio track (up to 6 channels),
 * Encoding any audio to AC3 and transmitting it over SPDIF.