[1] As I see it, that procedure could make your mixings compatible with current and future listening enviroments, because it synthetize coherent ITD according to the azimuth you choose at your artistic will. ... But you are clearly and expressly stating/asserting/mantaining that such type of mixing is
impossible!
[2] Remember, this is the science forum. You must test the hypothesis before you can rule it out.
Given your assertiveness, apparently you did test such hypothesis.
[3] I just don't understand why then Professor Choueiri insist that it is a possible path... He is professor of applied physics at Princeton University and he is the one who is
lecturing that new technologies will allow people to be truly fooled by audio... Apparently he is also driven by the same myth...
1. Not impossible, just impractical and artistically undesirable!
2. Effectively, every mix I've ever done is a similar sort of test.
3. Yes, apparently he is also driven by the same myth! Being a professor of applied physics at Princeton means he is an expert on applied physics, not an expert on recording, mixing and music production! I'm sure he knows way more about applied physics than I will ever know even exists but the example screenshot you posted of a mixing session indicates he's got no idea how music is performed, recorded and mixed. Or, maybe he does and he's either just talking "theoretically" or relying on the ignorance/myths of how audiophiles think music is produced in order to market a product? The example screenshot you posted would work as intended given ALL these conditions: A. If each of the instruments were recorded individually, B. With little/no natural reverb/room acoustics and C. If we were trying to create a single, cohesive acoustic space in the finished product.
Typically, NOT EVEN ONE of these conditions is practical or musically desirable, let alone all of them! For example, in most popular/rock based genres we need to individually process each of the instruments in a drumkit but ultimately we want it to sound like a drumkit (albeit not a drumkit which actually exists in the real world), not like a bunch of individual, unrelated percussion instruments. In practice then, we record the whole drumkit in one go (not each instrument in the drumkit individually), we spot mic each of the instruments AND we record the whole drumkit in stereo, plus we typically also have a mic dedicated to recording the room ambience (respectively called "instrument", "overheads" and "room" mics). We then process each of the instruments in the kit individually from the spot mics (EQ, compression, reverb, etc), mix with the overheads and room mic, create a stem for the drumkit and apply more processing to the kit as a whole. In practice, we end up with the relative timing of the instruments within the drumkit all over the place, severely compromised in preference to a subjectively aesthetically pleasing result. We would most likely do something similar with the strings/brass (although with less individual processing), then again with the singers (other than the lead vocal) and the guitars probably recorded individually. Each of these groups/stems would most likely have different reverbs applied. The lead singer maybe a small plate, the strings/brass probably a much bigger chamber or hall type reverb, the backing vocals maybe a bigger plate, the lead guitar maybe a stereo delay, the bass guitar probably very little reverb. There is no one room or coherent acoustic space that we are either recording, mixing or trying to create at the end of the process, which I've stated before! The software screenshot you posted clearly operates on the basis of a single reverb and single coherent acoustic space. So, Choueiri is correct, "it is a possible path" but going back to point #1, "possible" and "practical"/ "artistically desirable" are not at all the same thing!
[1] I see why my language may lead to a misunderstanding. Instead of "realistic ITD", I should have used "synthetic ITD, coherent with our spatial expectations".
[2] And why would a mastering engineer want to make current mixings compatible with future listening enviroments?
1. Yes, there is a misunderstanding going on here. You are misunderstanding both the idea of a "realistic ITD" AND of a "synthetic ITD, coherent with our spatial expectation". Music mixes are NOT coherent with our spatial expectation, they are created with acoustic information which couldn't possibly exist in the real world and which should sound like a bizarre, ridiculous, spatially incoherent mess but of course that's not how they appear. They don't appear like that because mixes are created by human beings whose brains (process of perception) work in roughly the same way as consumers' brains. In other words, when we mix we have little regard for what should be coherent, incoherent or expected spatial information, just for what sounds good and what sounds good is typically nothing like real (actual or synthesised) timing delays. It's bizarre listening to audiophiles go on about natural, transparent, realistic soundstages or "it's like being there", because there is no natural, realistic or "there". It's like having a photoshop'ed image of a unicorn and then people discussing/arguing about how natural and realistic it is, about how one video monitor makes the unicorn look more real than a different monitor.
2. They wouldn't, there's not the time or money to do that and typically, making the master sound good for one format compromises the sound for another. For example, despite virtually all network TV being made and broadcast in 5.1, most consumers still listen in stereo. This is why Dolby has historically dominated the film sound world, even it's first surround format was backwards compatible. All HDTVs contain licensed Dolby software which automatically down-mixes the broadcast 5.1 to stereo if neccesary but that down mix is compromised. It's a simple algorithm which works fairly well sometimes, not so well at other times. We have to check a down-mix when delivering 5.1 to make sure nothing really strange is going on and change the 5.1 mix if there is, this obviously compromises the 5.1 mix. In general, the stereo down-mix is acceptable but it's not as good as if we made a dedicated stereo mix. Dolby Atmos also has this feature, if you have a Dolby Atmos processor it will mix/down-mix according to your system, up to 64 speakers in your Atmos installation or to 7.1, 5.1 or stereo if you don't have an Atmos system. Despite this feature, most theatrical films have separate mixes (say an Atmos mix and a separate 7.1 mix) rather than relying on the down-mixing algorithm.
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