Originally Posted by MagnumX
Disney's locked object 7.1.4 configuration are the main example, but SDrucker's comments on how Gravity (Atmos version) is unusual in that it actually supports his Lc/Rc speakers (I think he said only one or two other mixes did).
There's a few. Off the top of my head, War for the Planet of the Apes, Groundhog Day, Ghostbusters II, Star Trek: Into Darkness, Unbroken, The House with a Clock on its Walls, and Oblivion, along with the REM "Automatic for the People" and Luca Terulli Rhapsody music discs. It's more common to NOT have Lc/Rc receive object passthrough than have it, but it's not as rare as you indicate. I haven't made up a full list on my 70-80 Atmos discs, but that's my slightly more than casual impression.
Frankly, his post more than any other implied the "out of the ordinary" speakers in Atmos have to be enabled in the mixer setup when it's mixed or they're just ignored. I'm not aware of the details of what affects as I don't mix soundtracks and don't have the software. I just read others comments on how their systems behave. Only a few have Trinnov systems on here so it's not like we get to hear a lot about whether all 34 channels are used in all (but disney) mixes so perhaps I misread SDrucker's comments?
I only have two pairs of unusual presence speakers - left/right surround 1 and the left/right center. But the mixer setup, as you call it, is all about the object locations that are assigned by the mixers, which take into account the closest speaker location that uses that 3D coordinates assigned to the object as it moves, as well you actually needing the speakers to be present in your setup. So far, only Trinnov allows you to do the unusual speakers as a matter of course. And remember, there's a hard limit - something like 12-16 objects total that can be decoded in a consumer Atmos mix, so the vast majority of content will always still be in the bed speakers and the static pair of stereo overhead objects at any given moment.
Regardless, even if it's just Disney, their ability to restrict Atmos to a precise channel output limitations (7.1.4) when the system can do so much more is RIDICULOUS. For that, I put the blame squarely where it belongs, not on Disney (give someone a knife and you don't expect them to ever pick it up?), but on DOLBY. If they want their system to be utilized in the way it's designed, they can't give the studios tools to bypass the object system and turn it into an 11.x CHANNEL system. WTF is the point of Atmos and all the commercials about "Objects" when Disney can just come along and BYPASS it??? It's very disappointing and I imagine 3x as disappointing (as in around 2/3 the channels are never used) for those that have put money into a system capable of FULL home Atmos. The renderer can render down just fine to 7.1.4. There is no need for Disney to LOCK IT DOWN. But then they've also been ignoring THX/Dolby specs for volume settings, dynamic range and everything else, making a 21st Century MOCKERY of Cinema sound for the home. Things sounded better in some respects from them in the 1990s or even back to 2011 (TRON: LEGACY) and now I wouldn't trust them with a 4K TRON: LEGACY in Atmos for that very reason. They'd neuter it in the process and ruin one of the best soundtracks they ever put on on home video.
So far, it's only Disney that seems to have a policy of locking content to 7.1.4 or possibly 7.1.6. I agree what Disney does is disappointing - enough that I don't buy Disney UHDs unless someone at home absolutely wants to see them - but keep in mind that mixer styles are ideosyncratic. Meaning there are movies that looks effectively "preprinted" to 7.1.6 or 9.1.6 (Red Sparrow is an example of that one), others that just have one pair of static stereo overhead objetcs like Saving Private Ryan (if you do 7.1.4 they're apparently split evenly between front and rear tops, but if you do 7.1.6 that object winds up in the top middle), still others where they use side surrounds 1 and wides, but not left/right centers, etc.