ATMOS delay compensation

[angelo panetta]

Dolby has told me that because of the way they route audio in and out of pro tools, the Dolby Atmos Production suite renderer bypasses the delay compensation.


I have done many tests and have not found any consistent way of adjusting for this. At first I thought I only needed to ad "time adjuster" plugin to the object tracks. But then in other sessions there were also other adjustments I need to make depending on my plugins. I cannot seem to find any constant formula.



Each Pro tools track tells me the "dly" "+/-" and "comp" reading. Can ANYONE tell me how I should compensate for delay when using the Atmos Production suite?

[Ryan Young]

I don't know much about the Renderer, but I'm also curious if you should print back into Pro Tools or render from the Dolby software. Are there any delay issues using the Dolby method?

[angelo panetta]

Hey Ryan,
There is a total delay when you print a Master Atmos file.

I've taken re renders back into sessions to adjust for the overall delay. That's fairly easy. I'm just trying to get a handle on how to adjust for individual track delay.

[Ryan Young]

Thanks for the info! Curious for your answer, too.

[reichman]

Are you using the Send/Return config, or the Dolby Audio Bridge config? Tell us more about your setup.

[angelo panetta]

Hey Nathaniel,

I took a look at your website and I see AMTOS in your workflow. Are you using a hardware or software renderer?


I am using Pro tools 12 with the 32 channel dolby atmos template that came with the dolby atmos production suite 3.0. Everything is working perfectly and I have been mixing projects and films with the atmos production suite. Because I am using the software renderer there is no delay compensation, as per Dolby's design. I have been compensating for this by putting 2 pops on each channel and making the proper delay adjustment.


I am asking if there is a better way.



To be clear, if I bypass the renderer and just keep the session within pro tools, (with delay compensation on of course) there is no issue with delay compensation. Also a hardware renderer will not have any delay issues.

[angelo panetta]

So here's Dolby's explanation of the delay issue for those who are interested in resolving it in the Atmos production suite.


Delay compensation in Pro Tools is on the physical output. The inputs to the renderer come via the send plugins which are on aux tracks so automatic delay compensation for plugins is not applied. When you put reverb on tracks that feed the Production Suite via the send plugin on aux tracks the audio needs to be shifted earlier to maintain sync. In Pro Tools if you go to View/Mix Window Views/Delay Compensation you can see the amount of the shift (in samples) that will need to be applied.


When using the RMU with physical outputs you don't need to shift anything earlier as the plugin delay is compensated for via the amount in the Delay Compensation view. However the RMU itself has a fixed latency of 44ms so you will need to shift any re-renders that you record back into Pro Tools once the recording is complete. Using a 2pip/plop is the best way to do this.


Hope this helps.


Best,
Adam

[[email protected]]

I also use the Atmos renderer on an HDX system using the send and return routing. Here is my trick for using TimeAdjuster and getting everything correct.

On my system, in order to get an object to be in time to a bed you need to add 34 samples.

Also using TimeAdjuster, 0=4 samples, so add 4 as an offset.

At the beginning of the session, I disable the plugin delay on the Atmos Return channels

Now I set up the mix in 5.1 or stereo in my room. Get it pretty close. setup plugins, auxes, etc. DIALED.

Now I insert TimeAdjuster as the last plugin on everything that feeds into the mixbus. (There may be other things like trigger tracks that will not get TimeAdjuster)

Now I go through the tracks, read the cmp # in the Delay Comp display, If the track will be routing to a Bed I add 4 samples and enter into timeadjuster. then route the track. If it is routing to an object, I add 38 samples and enter into timeadjuster. and rout the track.

So,
Bed = cmp#+4
Object = cmp#+38

Obviously once you get this far you will have to compensate for any plugin changes you make after. you can do the math or, just route the track to an ouput, and reread the delay comp # and redo the math and rerout the track!

[angelo panetta]

Hey BMAP I am sure you are aware Dolby solved this problem with the new renderer, which no longer uses send returns but now routes the audio through the outputs, which allows for the use of delay compensation

[[email protected]]

Actually using send and return is the only way I have been able to use HDX processing for plugins. If there is another way I would love to find it. Also running the audio bridge still requires timeadjuster for any object tracks as these are sent to the renderer before the output.

I have only been running Atmos for a couple of months, and it took me quite a while to get to a usable workflow. I would love to be wrong about this, so if you have a setup that enables HDX and uses delay compensation, I would love to learn.