Not all movies, right? According to AH's
latest article, there are movies mixed in 6.1 and 7.1.
Well Adam, from what I gathered, the studio mixes are always done in 5.1-channel. The one or two rear added channels are derived from the two surround channels. This information is directly from a professional film mixer for big Hollywood movies, including blockbusters. Also it has been confirmed by Mr. Roger Dressler, the big shot from Dolby.
Plus I have the latest editions of Widescreen Review, where it is also confirmed.
The films are mixed as 6.1 and 7.1-channel, but they are not discrete, they are derived.
I'll take this as a true fact.