Stereo vs Dolby pro Logic II

[kalafalas]

I have a MacBook Pro (13", mid 2010) and i have been using handbreak on the Apple Universal preset to rip my DVDs. It defaults on AAC (core audio) Dolby digital Pro Logic II, and i have been changing this to AAC (core audio) stereo because i do not own a surround sound system, i will be watching these movies wither using my built in laptop speakers, my apple in-ear headphones, or my logitech z3200s.

My understanding of Dolby Pro Logic II has always been that its two channels, with added "hints" that tell a compatible surround system to artificially separate it out into surround on the fly. So effectively, on a stereo system, it shouldn't be any different than choosing the stereo option.

Yet, when I choose Dolby Pro Logic II instead of stereo, my movies sound much louder and unnatural, like the sound stage has been pushed way far out. A similar effect to when turning on the "sound enhancer" feature in iTunes and turning the slider all the way up.

Why is this happening? shouldn't both versions be the exact same when played through a stereo system? Thats what everyone has said in any recent posts about Dolby Pro Logic II I could find, Or am i missing something?

[protovision]

IIRC, because of the way the channels get muxed into ProLogic, you would hear some loudness @ stereo:

ProLogic Muxing (only 2 channels, expanded to 2 + 2 fake):

- front left channel (real)
- front right channel (real)
- center channel (fake, audio that is the same in front l & r gets sent here)
- rear surround(s) (fake, is actually mono, front left audio - front right audio = rear)

so when these get 'flattened' into 2 channel stereo, the extra muxing/phasing gets dumped into the 2 channels, and louder (and sometimes out of phase, which sounds like an echo, or very far away)