Our post last week about the upcoming home version of the Dolby Atmos surround sound format elicited some follow-up questions that weren’t covered in the original conference. I asked Dolby to comment, and the firm has provided some answers.
This post should be read as an addendum to last week’s article on Atmos. Please see that one first for general information about the home version of Dolby Atmos.
In the Comments section to that piece, our readers came back with some good questions. I also thought of a new one myself. I reached out to Joshua Gershman, the Public Relations Manager for Dolby Labs. After conferring with his colleagues and tech experts, he responded with the following:
Q: How much extra disc space will an Atmos track take up on a Blu-ray? Are studios likely to have to choose between either Atmos or 3D in order to maintain a decent video bit-rate, or can a Blu-ray accommodate both Atmos and 3D on the same disc without too much compromise?
A: This depends on the complexity of the content itself. Our initial goals are to minimize overhead to 20% or less. We don’t expect video bitrates to be compromised [due to] the addition of the Dolby Atmos soundtrack on a Blu-ray disc.
Q: One reader has a small dedicated home theater with his main listening position against the back wall. Will this limit him to only to a 5.1.2 setup even though he’d like to use 4 ceiling speakers? How will the sound move across the Atmos channels if the top rear speakers can’t be behind the listening position?
A: A 5.1.2 with 2 overheads in front seems to be the best route. If he is limited to a 5.1.2 setup, it’s recommended to place the two overheads in front of the listening position in the ceiling. Or choose to introduce Dolby Atmos enabled speakers (integrated or module design) to his left and right front speakers.
Something he may want to try is to install the front two overheads as outlined above and experiment with placing Dolby Atmos enabled speakers modules on the side walls in the rear of the room above listening level. The use of Dolby Atmos enabled speaker modules in the rear may create the more diffused soundfield he seeks.
[In a later message, Josh forwarded this additional note.]
Suggest he consider moving the couch slightly forward; installing overhead speakers with wide diffusion characteristics behind the couch is also an option.
Q: Many viewers with traditional 5.1 or 7.1 systems already mount their surround speakers above ear level, either on the ceiling or high on the walls. Does this change the recommendation for a 7.1.4 minimum configuration? I would think that if the surround speakers are already up high, 7.1.2 would be a natural first upgrade. Or is it recommended that they add new surround speakers at seating level?
A: Dolby’s recommendation is that surround speakers do not exceed 1 ½ times the height of the listening position. They could consider adding Dolby Atmos enabled speaker modules above the left back and right back surrounds.
If you have additional questions about Atmos, let us know in the Comments and I’ll see if I can get more answers.