DVD player software such as Power DVD or Win DVD includes a Dolby AC3 decoder.There is also a FREE (unlicensed) CODEC called AC3 Filter.
I suppose OS X software is too much to ask for.
QuoteI suppose OS X software is too much to ask for. I assume you can play DVDs (with surround sound) on a Mac. ...I don't know but I'd almost bet OS-X can play DVDs out-of-the box with no additional software.
Which mac do you have?
Dolby Digital (AC3) can output 6.1 channels thru matrix decoding of Dolby Digital EX streams. There's a free encoder, Aften, which has the feature of setting the EX flag if you want to use it.