ATMOS in DCP/CPL names becomes IAB

[Carsten Kurz]

As Dolbys' ATMOS is no longer the only immersive audio brand, and because the object based audio data stream has been standardised in SMPTE ST 2098-2, they will be moving from using 'ATMOS' in CPL titles towards 'IAB' as a generic marker for immersive audio ('Immersive Audio Bitstream').

e.g. NoTimeToDie_TLR-H_F_EN-XX_INT_51-Atmos_2K_UP_20201012_MPS_SMPTE_OV would become NoTimeToDie_TLR-H_F_EN-XX_INT_51-IAB_2K_UP_20201012_MPS_SMPTE_OV


So, don't be surprised if they start distributing DCPs with 'IAB' in their names instead of ATMOS. ATMOS versions are not missing. IAB will play on your ATMOS system without issues. Same for trailers as well as features.

https://registry-page.isdcf.com/illustratedguide/

[Marcel Birgelen]

And as a result, the only way to know WHAT "Immersive Audio Bitstreams" are actually present, will require to look in the provided CPLs? Nice progress...

[Carsten Kurz]

I think even the CPL will not offer that insight. On that level, it will be 'generic' IAB. One would probably have to look into the MXF metadata to recognise the source of the IAB.

[Marcel Birgelen]

Well yeah, I've looked at the CPL level and there is indeed nothing mandatory there that describes the exact underlying format of the IAB bitstream, so you have to look at MXF level to get a clue...

[Steve Guttag]

It seems like a poor decision to use a generic name when it does not always encompass all variants. So, if IAB was the desire...then it should have an hyphenated letter to denote the type and that could be combined to denote the types. For instance, IAB-A for Atmos, IAB-D for DTS-X and so on. So, if there are both DTS and Dolby IAB, then IAB-AD could denote those two but no others.

[Marcel Birgelen]

If the intend is to shorten an already long and convoluted naming scheme, I guess that would've been a sensible option. To me it looks like nobody asked anybody in the field about what they would think about such a change, as this obvious flaw would've come to light almost immediately...

[Leo Enticknap]

Assuming that any IAB data will play on all systems, not a problem. But if a DTS-X stream won't play through a CP850 (for example), it's going to cause confusion.

[Marcel Birgelen]

I failed to follow these developments in the past few months, I guess I must have been distracted.... But... Well, it's highly confusing as always. As most of you may know, they were working on this new, SMPTE 2098-2 standard for immersive audio: IAB Profile 1. This IAB Profile 1 is essentially based on Dolby Atmos, so I guess IAB Profile 1 content should be 100% compatible with Dolby Atmos playback infrastructure. In the future, there could possibly be Profile 2, 3, etc., which would extend upon the specs in SMPTE 2098-2 and could possibly need more beefy audio renderers.

I don't know where that leaves DTS-X, as DTS-X is NOT IAB Profile 1, but Barco's APX AuroMax claims to be SMPTE 2098-2-compliant... Does that mean this device can also play legacy Dolby Atmos? I guess not, I guess there will be this tiny bit of difference between the bitstream that makes Atmos incompatible with IAB Profile 1...

So, if the bitstream is in IAB Profile 1, then the CPL label "IAB" is essentially correct, as the Immersive Audio bitstream isn't DTS-X, it isn't Atmos, it's "SMPTE 2098-2 IAB Profile 1"...

Would be interesting if there is a test-DCP out there, to see if our CP850 will just accept this newfangled IAB Profile 1 bitstream instead of "legacy" Atmos...

[Stefan Scholz]

I support the IAB, but only if this is for a universal bitstream based immersive sound, that can be played on any system. Get rid of proprietary systems, use universal, royalty free. AS it was the initial goal of 2098 board.
To start a -1 type that might be compatible with -3 or vice versa, Type 2 not playing -3 files and so on is a bad approach and will not support acceptance, neither in exhibition nor in production.

[Harold Hallikainen]

IAB is SMPTE ST 2098-2 ( https://registry-page.isdcf.com/audioconfigs/ ). DTS now has a "front end" that parses this bitstream and drives their renderer. ST 2098-2 is "forward looking" and has features that no current system supports. To allow operation at this time, ISDCF set up Profile 1 that has the features every system supports at this time (which is the same as fielded ATMOS systems). The original draft of ST 2098-2 was provided by Dolby. Again, it was "forward looking" with features not supported at the time (and not yet supported). The use of IAB is an effort to not use proprietary name for a standardized bitstream. Manufacturers are free to brand their renderers as they choose (ATMOS, AuroMax, etc.).

Harold

[Marcel Birgelen]

Does anybody know if the IAB Profile 1 and Atmos (for Cinema) bitstreams are the same or is there a difference in the format?

[Carsten Kurz]

They should be the same, as Dolby was part of the SMPTE standardisation as well as Profiling. The intention of Profile 1 clearly was to have NO compatibility issues between bitstreams and systems.

[Marcel Birgelen]

If they are the same, then I suppose all other "IAB Profile 1"-compatible equipment should be capable of playing back "legacy" ATMOS tracks? I guess they can't call it Atmos, due to licensing restrictions, but their "immersive bitstream renderer" should be able to parse the format and render it.

[Carsten Kurz]

That's the idea.

[Harold Hallikainen]

ISDCF ran extensive tests to establish profile 1. The profile is described at https://isdcf.com/papers/ISDCF-Doc15...-202006012.pdf . There is a table of the tests and the results at https://isdcf.com/MeetingNotes/Meeti...212vPOSTED.pdf .