SurCode Dolby Digital V2 A surround encoder fully licensed and certified by Dolby, which includes all encoding options  
The audio track of a DVD-Video consumes a large amount of disk space. For example, two hours of audio (at 48kHz 16-bit stereo) uses nearly 1.4GB of the DVD's 4.3GB of space. Dolby Digital encoding is an excellent option for audio on a DVD-Video disc (and other media) because it reduces the size of the audio files typically by a ratio of 8:1, yet still achieves excellent sound quality. SurCode Stereo for Dolby Digital can free up considerable space on the disc to allow for more video.
SurCode is licensed by Dolby Labs
Encodes 5.1 Surround Sound or stereo into a Dolby Digital .AC-3 file
Accepts up to 6 .wav or .AIFF files for input
Stereo mixdown for auditioning Surround soundfiles prior to encoding