Dolby Atmos Questions?

[Bill Rigby]

Hey Cheesehead,

I am in agreement with you.

Workflow wise 7.1.4 would be a far more logical buss structure to communicate with DAPS. Especially internal PT bussing for Compression and Reverb management ( ie Stratus and Symphony Reverbs ).
This would also allow for accurate placement of moving elements in a bed (principally constrained for objects)
I realise there are existing workaround practices for this.
In my mind, this is a proposition improving existing practices for maximum flexibility and utilisation of resources.

I would even go 1 step further. 9.1.4.

Why?

1) It is physically impossible to deliver a theatrical mix intended for Cinema release in a small room.
But even though the mix would not be a final delivery, accurate speaker positioning is still important.

2) A small audio post studio intended for Home Atmos with accurate speaker placement for Netflix delivery could double as a remote Premix/tracklay facility for Theatrical Atmos. (Especially since the updated compatibility release of PT 2019.10 and DAPS.
As real estate becomes a more expensive commodity and commuting for employees environmentally unfriendly as well a cost in in time efficiency, outsourcing via high bandwidth ISPs is a commercial reality.

3)This facility could also utilise the Downmix/fold down to Ambisonic/Binaural for “3D or 360” immersive deliveries, utilising DAPS downmix/fold down Ambisonic/Binaural HTRF approximation capabilities.
For this to be possible small room monitoring must be Dolby spec but retain symmetry for acoustic balance when listening through DAPS.

Remember the VHS versus Betamax battle for market dominance?
Betamax was a Superior format but through sheer market share VHS became the standard.

Dolby Digital and DTS had the same tussle for market dominance and Dolby has been declared the winner.

The reason I brought this up, is because during that stage DTS had a speaker layout that was based on Quadraphonic and Soundfield Ambisonic (45 x 45 degrees with a centre channel) plus Lfe.
This is the same minimum speaker positioning that is optimal for 360 immersive in an acoustic space. Audio ease 360 embraces this and utilises 5.0 for its monitoring.

Dolby 5.1 adopted the LR 30 ( for maximum mono compatibility) x 110 degrees Surround (with raised height of the rear 110) plus centre channel and Lfe. It was stated at this time to have the best downmix /fold down compatibility with the Dolby theatrical releases ( there were no DTS theatrical releases at that time that I am aware of) This was also designed to have backward compatibility with Dolby Pro Logic II.
Dolby and DTS specification was based on all matched full frequency matched speakers with Lfe.

7.1 was the next standard that Dolby Released.
Speaker layout was Centre, 30, 60-70 (this varied), 110 and Lfe.

Also, for the “Home Cinema” environment it was recognised by the domestic market that only a small market of audiophiles had the desire to embrace the expense of large format full frequency speakers and dedicated real estate to accommodate them.
Amplified “Subwoofers” with Satellite speakers with a “matched” crossover and Hybrid stand alone amps amps flooded the consumer market as “Surround Sound” was for all consumers,not only for the audiophiles.
Foldown and downmixes had to be cautious of the LFe component of this development as the lower frequencies of the total “discrete” mix now occupied the place that used to be dedicated in principle only to the Lfe.

When Atmos, Auro 3D and DTS became the domestic “standards” the positioning of speakers settled a little around the Dolby market dominance with nominal speaker placement with flexibility . Also extra rears were added.

(ie; Centre 30 (nominal) to 22 , 70 (nominal) to 50, 110 (nominal) to 90, 150 (nominal) to 135.

The listening position of the overhead height speakers of the + 4 in the Dolby spec is placed in the center of a 4 equidistant symmetrical rectangular speaker setup.
Placed in line between the L,R and the 150 horizontal speakers at a vertical angle of the relevant 30, 45, 55 degrees above from the listening sweet spot for the front pair and the relative to front 125, 135, 150 for the rear overheads.

Now why 9.1.4 ?

A balanced matched full frequency speaker layout of Centre (add 30 degrees), 30 (add 40 degrees), 70 (add 40 degrees), 110 (add 30 degrees) , 150 speakers with the overheads symmetrically placed , all speakers full frequency with the bass management ability to be switched in and out to check for Subwoofer, satellite (now Soundbar Subwoofer compatibility) would give the mixer when monitoring through DAPS, the best option for compatibility with home theatre in downmixes of Ambisonic Binaural (aside for Binaural headphone checking) because it’s the closest to a balanced hemisphere environment and the overheads because of the 30 ,150 mono compatibility relationship would also assist in compatibility for the God speaker relationship in Auro.

If Protools 2020 x had an internal bussing 9.1.4 and DAPS, which gives you the ability to switch between the 30,70,110 layout to the 30,110,150 , 7.1.4 speaker monitoring layout, went one step further and incorporated both those layouts to make it 30,70,110,150, 9.1.4 .... the workflow would simple, flexible and balanced for better acoustic compatibility for all formats.

Whilst I am at it.... sorry to bore further you if you have made it this far.

A question that has gnawed at me for years and forum /web research has denied me the answer.
I came across this back in the days of Pro Control and Tascam DSM-7.1 monitoring.

The internal Buss Surround configuration in Pro Tools for as long as I remember and still is , FIXED at the Film Standard L C R LSS RSS LSR RSR LFE LTS RTS.

Whilst this is fine for sending elements of mono or stereo elements into any of the output surround environments (Smpte ,Film Standard, SDDS etc..., a problem arises when the fixed Film Standard internal bussing does not follow if you use SMPTE or SDDS output path order instead.
If you are using larger internal bussing 5.1,7.1 etc for environments that need to be bussed internally or musical or FX surround elements bussed into Symphony and Stratus 3D reverbs that return to the print master (The same question applied back in the day for Reverb one and 5.1), the mix path order is changed.
Hence your imaging Right and Center swap, LSS becomes Lfe, RSS becomes LSS, LSR becomes RSS,RSR becomes LSR, Lfe becomes RSR.. What gives?

L C R LSS RSS LSR RSR LFE LTS RTS
L R C Lfe LSS RSS LSR RSR LTS RTS

I understand that this is only a problem in the creation of content and not so much in the exports , split into mono and rearrange situations. But why haven't they made the internal bussing variable to match the output path order?
If you previously know the delivery standard, surely the internal bussing could be configured, so when you change the output paths, the internal bussing followed?

My 9.1.4 cents

Bill