Why do cinema and music Dolby Atmos layouts differ?

[sarumbear]

Cinema studio are trying to make their studio like cinema

https://imageio.forbes.com/specials-images/imageserve/62aa01212ed5bf813128a145/0x0.jpg?format=jpg&width=1200

They have to. It is a room to mix film soundtracks to be heard in at a theatre, hence it should be as close to a theatre. All major studios do exactly that.

 

[milotrain]

Speaking as an FX mixer who has worked in three rooms extensively (uncountable rooms occasionally) that started as 5.1 and became Atmos; the major reason that some rooms are less than ideal in their Atmos implementation (home Atmos, not theatrical Atmos), is because the room's guts were built before anyone considered sticking speakers in the ceiling. You have hardware up there to avoid, baffles, HVAC, lighting, sprinklers, etc that require positioning around. Then you have to select a speaker that actually works within the envelop of the positions you have and is voiced somewhat similarly to your main array (not impossible but not trivial).

Lastly you have to consider not just the intentions of Dolby but also the intentions of the room and the film maker. There are several instances where I've been in a room that Dolby measured as "acceptable" but a huge amount of potential acoustic energy was behind the MLP (sides slightly behind, rears behind, rear tops behind). This doesn't make a lot of sense because it means that that the soundscape will have a tendency to sound biased to the opposite end of the room that the screen is in.

 

[DavidMcRoy]

Speaking as an FX mixer who has worked in three rooms extensively (uncountable rooms occasionally) that started as 5.1 and became Atmos; the major reason that some rooms are less than ideal in their Atmos implementation (home Atmos, not theatrical Atmos), is because the room's guts were built before anyone considered sticking speakers in the ceiling. You have hardware up there to avoid, baffles, HVAC, lighting, sprinklers, etc that require positioning around. Then you have to select a speaker that actually works within the envelop of the positions you have and is voiced somewhat similarly to your main array (not impossible but not trivial).

Lastly you have to consider not just the intentions of Dolby but also the intentions of the room and the film maker. There are several instances where I've been in a room that Dolby measured as "acceptable" but a huge amount of potential acoustic energy was behind the MLP (sides slightly behind, rears behind, rear tops behind). This doesn't make a lot of sense because it means that that the soundscape will have a tendency to sound biased to the opposite end of the room that the screen is in.

This reinforces my observations based on my limited experience, having outfitted two home Dolby Atmos rooms with slightly different height speaker layouts. I don't think the system is all that delicate. Given that delay correction is a key part of implantation, it's mostly the angles to the listener which may vary a little.

Re: "acoustic energy from behind the MLP," it is my experience over nearly five decades that, in addition to damping first reflections elsewhere, the rear half of a room ought to be as dead as possible so that undue reflections don't swamp what's in the mix. I don't think this can be overstated. The LEDE or live-end-dead-end approach is exactly backward, in my opinion, and not just for a surround setup but for 2-channel stereo, as well.