AC3Tools Pro is the complete professional suite for AC3 files processing. With AC3Tools Pro, you can remaster AC3s, translate and recompose sound-tracks to DivX/XViD movies, compose several WAV PCM-files into 5.1 AC3-file.
AC3Tools Pro includes AC3 Decoder, AC3 Demuxer, and AC3 Encoder.
AC3 Decoder processes multi-channel AC3 file into two-channel MP3, WMA, WAV or Ogg Vorbis files. The algorithm used in AC3 Decoder splits audio channels to achieve surrounding effect as if you were listening to original AC3 file at 5.1 audio system.
According to Dolby Laboratories