Raimoraimo (Raimo Sound) asked a question.
Wides, the 68 pan position in Pro Tools and Speaker Snap, bugged / inconsistent between Atmos Home and Atmos Theatrical
As per the title. Wides handling is bugged and inconsistent accross Atmos Home and Atmos Theatrical. As it stands, Speaker Snap does *not* work for the wides in Atmos Home or with using the Dolby Atmos Renderer, instead it bleeds the signal to the front LR. The pan position of 68 does "snap" to only the wide speakers, so the new Pro Tools 9.1.6 paths map correctly this way. But on the other hand, the 68 pan position without Speaker Snap does *not* work in Atmos Theatrical with an RMU, instead it bleeds into the adjacent sides. The fix is to use Speaker Snap in Theatrical (which does work with the RMU), but this will eventually compromise the HT mix.
Thanks for reaching out. The behavior difference you are seeing is a result of how speaker snap interacts with spatial coding. When speaker snap is on in PT and spatial coding is enabled in the Renderer, there will be some bleed when the pan position is at 68, as with spatial coding snap happens to the canonical (7.0.2) beds. Theatrical does not use spatial coding, and the new 9.1.6 pro tools 'object bed' does not use speaker snap, which is why you are not seeing the bleed in those instances.
If you are trying to pin an object to the wides, you will want to turn off speaker snap in PT and use the pan position you mentioned.
-B
"If you are trying to pin an object to the wides, you will want to turn off speaker snap in PT and use the pan position you mentioned."
-This seems to be not correct, as I saw different behaviour visiting the theatrical mixing stage (with full RMU) before posting this. We saw bleed into adjacent objects when snap was off and the pan position was 68 forward in PT (so set correctly).
I've now suggested to the mixing team that for the theatrical mix the snap should be on, but if there is a home Atmos version, snap should be set off for that.
The explanation about spatial coding seems quite weird, as spatial coding is ever used for home content, so snap is essentially useless for non-theatrical...?
-Mikko
Snap will work for the 7.0.2 speakers with spatial coding, the bleed happens with the wides.
In the cinema renderer when the object position is 68, it only hits the wides, but there is some bleed between Lw1 and Lw2. If you want only Lw1 to be hit then speaker snap should be on. This likely has to do with the resolution of the Pro Tools panner.
Thanks for your diligence, let me know if you have other questions.
-B
This is unfortunate. Is there any possibility that the spatial coding could be updated to account for the wides and to snap to work properly in Atmos Home as well (I wouldn't call it being limited to 7.0.2 as "working properly", tbh)?
The intention with spatial coding is that as an encoding process it is designed to work with the widest number of downstream playback layouts (which are unknown at the time of encoding/mixing) and 7.0.2 for speaker snap has historically been the most prominent.
-B
Also, the less behavioural differences we have between Home and Thatrical the better, IMHO (although beds vs objects / beds as arrays is a logical one - I would still personally ditch the Room Size Delay Compensation from the Theatrical Bed...)
Out of curiosity, what are you referencing in regards to the advertisement of speaker snap?
-B
"Depending on the sound in question, this may or may not be desirable. If you would prefer the sound to remain as a point source, emanating from a single speaker only, then you may use Speaker Snap to tell the Renderer to always ‘snap’ the panning to the nearest speaker position."
The next paragraphs gives a vague warning of using snap close to the front / screen, but it doesn't explictly tell that the snap setting is omitted for wides in Atmos Home. All in all, snap should work for *any* speaker for it to be a useful setting to have, IMHO. Most Atmos theatrical content gets converted to Atmos Home after all, and I doubt that the conversion process always involves minutiae like double checking Speaker Snap settings across mixes (if the operators are even aware of this behavioural difference, as it is not really documented anywhere).
-Mikko
-B