This virtual item is needed not only for playing media files with AC3 or DTS streams; it is also useful in case you use a program like VirtualDub, which works with such audio tracks.
To watch movies, we suggest you to use the AC3Filter DirectShow codec
The particle ACM
in the name of the codec refers to the fact that it works with Windows multimedia framkework such as ACM (Audio Compression Manager).
It also allows you to decompress your Dolby Digital encoded files to WAV or MP3.
After installing this software to your computer, you will be able to play any AVI or WAV file containing AC3 or DTS audio tracks.