There seems to be much confusion in this thread on how Atmos works and what you get on 5.1 systems. While AYanguas is correct. I feel like the implications haven't sunk in.
Let me address something basic he talked about. ALL Atmos recordings have either a 7.1 TrueHD base track (100% backwards compatible with older decoders because it IS a TrueHD track. NOTHING is different about it at all) or a 5.1 or 7.1 DD+ base track.
The mixing engineer is most certainly going to listen to the base track playback at some point or numerous points. They'd have to be an idiot not to. They can easily do this at any time because all Atmos setups are still based on 5.1/7.1 are layouts! I can easily switch to 7.1 or 5.1 playback on my Marantz receiver either by selecting the TrueHD base layer in surround mode (which I can then send to DTS Neural X to upmix instead if I prefer) or I could tell the receiver I have a basic 5.1 or 7.1 layout and it will handle it automatically.
The base 5.1 or 7.1 mix has everything placed where the mixing engineer wants it! He can place sounds in completely different locations if he desires it because the meta layer (that older AVRs can't see) contains all the sounds associated with objects. The way the Atmos mix works is rather incredible. It actually phase cancels out the same overlapping sound in the base soundtrack!
That's why you don't get duplicate sounds and the meta layer doesn't have to carry a complete separate soundtrack! It only cancels out objects. It can then render them anywhere in the room including rear surrounds (7.1) even when the base layer is limited to only 5.1!
There are DD+ 5.1 based Dolby Atmos demos that do precisely this while the exact same demo on one of their demo Blurays is TrueHD 7.1 based and they render exactly the same on an Atmos receiver (tested thoroughly here).
ATMOS is a room based format in the sense that sounds are supposed to come from the same place for all listeners. In practice, this may not happen with lower speaker count setups which is why Atmos at the theater has even more speakers employed (up to 64 speakers in the first generation units with support for 128 channels/objects internally).
This differs from a traditional 5.1 or 7.1 movie theater setup which might employ dozens of speakers, but the are arrayed copies of those same 5.1 or 7.1 channels. This makes the output user orientated (i.e. The "left side surround" in a 7.1 system will seem to come from the surround speaker closest to the listener, not one specific speaker in the room like Atmos can do.
The Atmos presentation therefore will be different for you when you sit in different places in the theater (i.e. A sound might be behind one person, but in front of another because it's stationary in the room). Thus, the notion of "one correct intended mix" is erroneous in the sense you think everyone is meant to hear the same thing. No. It's an adventure of sorts. The "intended" locations are specified and your specific system does the best it can with what you've got to represent it. That is by all means intentional by the mixing engineer or he wouldn't be using Atmos in the first place.
If you go see a concert live, doesn't the presentation change depending on what seats you get for the concert? Some seats might be considered better than others,but it's also subjective. Atmos attempts to capture the soundfield for the arena and you can play it back more or less accurately with your room/setup needs and where you sit in it. But that's by design. Similarly, the base 5.1 or 7.1 soundtrack attached is also b design. If it sucks, it's a bad mixing engineer's job/vision/intent not Atmos' fault.
Yes, you can include a separate 5.1 or 7.1 (or quad or whatever) mix like Steve Wilson did for his latest album where he did the 5.1 mix alone, but had assistance with the Atmos mix. So they sound different on a 5.1 system because they are different mixes.
You can even view the Atmos object placements on a high end Trinnov processor. It shows a rectangular room/grid with how many speakers you're using up to 32.1 and the objects appear as moving balls while the speakers light up when either the base layer or an object renders to it (including in part for pans).
Atmos is capable of rendering a mixing engineer's vision for whatever level his own mixing station can represent including the base 5.1 or 7.1 mix. Most don't have all 32.1 speakers to try out, buy then most of those speakers outside the 7.1.4 base rectangle exist for anchoring sounds for more rows of seats and off-axis listeners in general and thus more precision, not really "new locations" of sound as the all fit into divisions within that base 7.1.4 grid.
Yes, having less than 7.1.4 (e.g. 5.1.2, 5.1.4 and 7.1.2 are common) means some sounds will get moved, but it's inherently no different than moving rear surrounds on 7.1 system to general surrounds on 5.1 system. If you want more accuracy or for more seats ir larger rooms to sound as good, you may need to upgrade to get there.
I know this is long, but hopefully it clears some things up about Dolby Atmos.
Let me address something basic he talked about. ALL Atmos recordings have either a 7.1 TrueHD base track (100% backwards compatible with older decoders because it IS a TrueHD track. NOTHING is different about it at all) or a 5.1 or 7.1 DD+ base track.
The mixing engineer is most certainly going to listen to the base track playback at some point or numerous points. They'd have to be an idiot not to. They can easily do this at any time because all Atmos setups are still based on 5.1/7.1 are layouts! I can easily switch to 7.1 or 5.1 playback on my Marantz receiver either by selecting the TrueHD base layer in surround mode (which I can then send to DTS Neural X to upmix instead if I prefer) or I could tell the receiver I have a basic 5.1 or 7.1 layout and it will handle it automatically.
The base 5.1 or 7.1 mix has everything placed where the mixing engineer wants it! He can place sounds in completely different locations if he desires it because the meta layer (that older AVRs can't see) contains all the sounds associated with objects. The way the Atmos mix works is rather incredible. It actually phase cancels out the same overlapping sound in the base soundtrack!
That's why you don't get duplicate sounds and the meta layer doesn't have to carry a complete separate soundtrack! It only cancels out objects. It can then render them anywhere in the room including rear surrounds (7.1) even when the base layer is limited to only 5.1!
There are DD+ 5.1 based Dolby Atmos demos that do precisely this while the exact same demo on one of their demo Blurays is TrueHD 7.1 based and they render exactly the same on an Atmos receiver (tested thoroughly here).
ATMOS is a room based format in the sense that sounds are supposed to come from the same place for all listeners. In practice, this may not happen with lower speaker count setups which is why Atmos at the theater has even more speakers employed (up to 64 speakers in the first generation units with support for 128 channels/objects internally).
This differs from a traditional 5.1 or 7.1 movie theater setup which might employ dozens of speakers, but the are arrayed copies of those same 5.1 or 7.1 channels. This makes the output user orientated (i.e. The "left side surround" in a 7.1 system will seem to come from the surround speaker closest to the listener, not one specific speaker in the room like Atmos can do.
The Atmos presentation therefore will be different for you when you sit in different places in the theater (i.e. A sound might be behind one person, but in front of another because it's stationary in the room). Thus, the notion of "one correct intended mix" is erroneous in the sense you think everyone is meant to hear the same thing. No. It's an adventure of sorts. The "intended" locations are specified and your specific system does the best it can with what you've got to represent it. That is by all means intentional by the mixing engineer or he wouldn't be using Atmos in the first place.
If you go see a concert live, doesn't the presentation change depending on what seats you get for the concert? Some seats might be considered better than others,but it's also subjective. Atmos attempts to capture the soundfield for the arena and you can play it back more or less accurately with your room/setup needs and where you sit in it. But that's by design. Similarly, the base 5.1 or 7.1 soundtrack attached is also b design. If it sucks, it's a bad mixing engineer's job/vision/intent not Atmos' fault.
Yes, you can include a separate 5.1 or 7.1 (or quad or whatever) mix like Steve Wilson did for his latest album where he did the 5.1 mix alone, but had assistance with the Atmos mix. So they sound different on a 5.1 system because they are different mixes.
You can even view the Atmos object placements on a high end Trinnov processor. It shows a rectangular room/grid with how many speakers you're using up to 32.1 and the objects appear as moving balls while the speakers light up when either the base layer or an object renders to it (including in part for pans).
Atmos is capable of rendering a mixing engineer's vision for whatever level his own mixing station can represent including the base 5.1 or 7.1 mix. Most don't have all 32.1 speakers to try out, buy then most of those speakers outside the 7.1.4 base rectangle exist for anchoring sounds for more rows of seats and off-axis listeners in general and thus more precision, not really "new locations" of sound as the all fit into divisions within that base 7.1.4 grid.
Yes, having less than 7.1.4 (e.g. 5.1.2, 5.1.4 and 7.1.2 are common) means some sounds will get moved, but it's inherently no different than moving rear surrounds on 7.1 system to general surrounds on 5.1 system. If you want more accuracy or for more seats ir larger rooms to sound as good, you may need to upgrade to get there.
I know this is long, but hopefully it clears some things up about Dolby Atmos.
