Delay Compensation Problems with Dolby Atmos

[critictalk]

So if we don’t want any latency problem we have to use RMU or secondary machine for monitoring?


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[audiogamble]

Originally Posted by critictalk

So if we don’t want any latency problem we have to use RMU or secondary machine for monitoring?


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As it relates to this specific bug, it seems to be affecting all configurations. Ive since successfully reproduced this on other systems, and was able to get avid to escalate this to be treated as a pro tools bug.

[LDS]

Originally Posted by audiogamble

So as far as I know, this is expected behaviour with Aux IO. There's an FAQ here that breaks it down: https://avid.secure.force.com/pkb/ar...sked-Questions

Aux IO should in theory be good enough for monitoring an atmos mix but shouldn't be relied on for a frame-accurate sync, and can't be expected to re-render back into pro tools at a consistent timing.

My specific issue doesn't relate to this though. The issue I'm having is that OUTPUTS fall out of sync despite pro tools' delay compensation not reporting latencies above the threshold by which things should actually fall out of sync.

It says in the FAQ that this shouldn't happen. It also addresse your problem specifically.

"Signal sent to Aux I/O outputs will be delay compensated within the session, and it will be in phase once it reaches the output of a given device. Aux I/O inputs and outputs are not delay compensated though. This is because latency values sometimes change between launches, after changing the H/W buffer setting, or after encountering an AAE error, so it cannot be properly compensated. This means that Aux I/O outputs may not align with other interface outputs, and signal recorded with Aux I/O devices won't be perfectly time aligned."

I'll reiterate, that the problem I'm reporting seems to be an Atmos issue, and not exclusively an AUX IO issue. However, AUX IO seem to amplify the problem by lowering the threshold even lower by which outputs will fall out of sync.

By design, outputs should remain in sync unless there is a red delay compensation value. That's not happening in some circumstances when mixing atmos with pro tools.

It is all inter-related, I think. AUX IO shouldn't have widely more drift than aggregate audio devices, but it does. HDN should have lower latency with lower buffer settings, but it doesn't. And then there are just weird delay compensation bits like the colour codes being highly confused in a totally empty session, which I have never seen before.

All of it has one common denominator -> Pro Tools with Dolby Atmos.

[audiogamble]

Bug has been submitted and is being worked on as the following:

PT-295007 [ADC compensation limit changes with HW Buffer Size in Dolby Atmos DAB workflow. The dly and cmp indicators do not turn red when limit is exceeded.]

[LDS]

Originally Posted by audiogamble

Bug has been submitted and is being worked on as the following:

PT-295007 [ADC compensation limit changes with HW Buffer Size in Dolby Atmos DAB workflow. The dly and cmp indicators do not turn red when limit is exceeded.]

Well... it is half of it at least. Avid are totally refusing to believe that there is an issue with HDN + Atmos when using an external renderer. I opened the case 7 weeks ago and have only just received my third email reply today. Thankfully it was more than one sentence this time, but they basically tried to blame RME HDSPe settings and drivers running in DAMS as the reason why the native sample buffers have no affect in Pro Tools on Pro Tools HDN hardware...

Let that sink in for a minute.
They blamed a totally different app...
Running a totally different audio interface...
Connected to a Pro Tools rig through MADI...

...as the reason why the native sample buffer in Pro Tools has no affect on the RTL of HDN hardware.

You can't make that stuff up. It genuinely feels like Avid Support is more focused on saving face than trying to fix problems. $399 a year to waste more of my own hours to jump through Avid's stupid hoops to show that swapping the HDSPe card and MADI for Dante and DVS lands me in exactly the same situation with exactly the same HDN/Pro Tools/Atmos related issues...