Atmos external renderer

Hi there

Can anyone using Atmos with an external renderer report back on how that is working out for you? I find that (with the internal renderer), as things start to get interesting in an Atmos mix, I start getting clicks due to the 512 buffer and resource issues of taxing high channel count plugins.

I have a Hackintosh that I can I/O with via MADI. I’m tempted to get DAPS and try things that way with a larger buffer on my Nuendo PC. But don’t want to waste money if it’s clunky and very high latency roundtrips. I blew out my DAPS demo a year ago as I was initially investigating Atmos, so any reports appreciated.


I am using the external render and not having any sound issues at all and when use the internal render even on big projects there is no sound problems that i am aware of.

I am a new user of both the internal and external renderer for Atmos. Mostly I use Nuendo’s internal renderer because the latency is lower with it. In the Nuendo section of the Dolby Atmos Production Suite Quick Start Guide, it recommends setting the buffer size of the Dolby Audio Bridge to 1024 samples at 48 kHz or 2048 samples at 96 Khz. I notice the latency because sometimes I am still composing or noodling on my digital keyboard and software instruments before the Atmos mix is finalized. I found the input and real time playback to be borderline slow (workable, just a little slow) with the recommended buffer setting. I can live better with the 512 samples setting of the internal renderer. You may not be worried about this type of latency if you are mixing final audio. I think Mathew’s comment above is true, if you take real time composing out of the equation (which probably is what most people would do.)
At the moment I mostly use the external renderer to import files from Nuendo and export them to other formats like mp4. For my next steps, I’m going to play around with the buffer size of the Dolby Audio Bridge to see if I can get away with less than the 1024 samples recommended for 48 kHz.

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Thanks both for your feedback, much appreciated. I’m pretty much exclusively mixing and mastering, so a bit more latency might not be such a big thing for me. My main machine can’t really keep up with my plugin aspirations in 7.1.4 so higher buffer seems pretty tempting.

I also like the idea of simultaneously generating re-renders in various formats, and switching between them with my software monitor controller. The lack of seamless transition of doing that internal to Nuendo means I don’t do it as much, and I’m fairly sure that the mix standing up in all downmix formats is super important.

@AdagioLearner what are you playing back the mp4 exports with/on out of interest?


No issues with the RMU (cinema renderer).

@BsoundNZ Apologies for my slow response. Dolby recommends using mp4 exports for QC on consumer devices. I use them on my iPhone and imported into Apple TV.

I have an update since my last reply: I have returned to using the external renderer all the time. I found that I could not use an aggregate device on my macBook as it was the cause of the poor latency and occasional audio clicking. Using the Digital Audio Bridge device alone I’m getting an acceptable 10.7ms and clean audio at 512 samples… The disadvantage is that in Nuendo (unlike some other DAWS) you must set the Dolby Audio Bridge as both the input and output device. Very silly because DAB is a one-way out virtual device. So I can’t include a recording mic within Nuendo because I can’t designate my audio interface as input, and an aggregated virtual device didn’t work for me. Luckily in DAPS I can send the output from there to wherever I want. And I can also add my mic for downstream live voiceovers in Loopback.

Latency is so good that I can practice and stream piano while listening to it rendered within DAPS. And in the corniest use of Atmos ever, I created in Nuendo an audio track of songbirds and then automated its Atmos object so that it moves aurally around in my sonic real estate. This is actually a very soothing way to practice Brahms, believe it or not.

I hope your experimenting with Atmos is going well and you are having fun with it.

Interesting that there is a recommendation for use at 96k in the Atmos Production Suite QSG, because unless I am badly mistaken Atmos is capped to 48k isn’t it?

You can work in the Production Suite at 96khz, but ADM deliverables are indeed capped/converted to 48khz.

Definitely not a flat-out recommendation that everyone should be mastering in 96. It’s merely an accommodation for high-res work flows. There is an entire page in the manual devoted to “considerations” for when working in 96.

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Apologies on the ‘recommendation’ error - I misread the earlier post.

Where and how does the downsampling (degradation) get done?
I confess the idea of an automated system doing sample rate conversion without me having full control over it is deeply worrying and it feels like an arbitrary limitation, although the reality is probably because of backwards compatibility with AC3 somewhere down the line (I know this is the case with Dolby ‘True HD’ as the outputs give me an MLP file at 96k and an AC3 file at 48k which is ‘hidden’ from the end user, leaving open the chance that even though the ‘True HD’ lights are on in either the amp or the player the user is actually hearing AC3)

Most of the mix work I do these days is from 2" tapes transferred to digital at 24/96, which is how it should be and this is the main reason I have decided not to go anywhere near Atmos - even for our Blu-ray - and instead use DTS-X, which does allow me to use 96k deliverables in the same way that DTS-HD Master Audio does.

No worries. Sorry, I don’t have a lot of info on this as my workflow is all 48. But if I’m not mistaken, Dolby has a free utility, the Dolby Atmos Conversion Tool, which performs downsampling, among other duties. I don’t believe the Dolby Atmos Renderer itself does any downsampling - it simply cannot create an ADM deliverable at 96khz.

Update: Coincidentally, I actually needed to install and use the Dolby Atmos Conversion Tool today to do some frame rate conversions. Super, super easy to use. Would certainly take no time to audition your master conversions against the originals to see if you’re happy with the results.

If working at 96 kHz is useful, then it should be done. If only to be able to fall back on a high-resolution master in the future. Who knows what formats the future will bring.

This probably has more to do with e.g. storage space. At least when it comes to consumer Atmos mixes. Atmos is already pushing the limits. If you were to use 96 kHz instead of the usual 48 kHz, a TrueHD track with Atmos would literally ‘burst’. There would not be enough capacity on a (UHD) BD to play such a track.

It is indeed somewhat unfortunate that many Blu-ray players display the track as “Dolby TrueHD”. However, this should not happen with an AV receiver. If the player is connected via an optical cable, for example, or does not support TrueHD, it will access the lossy AC-3 track. In this case the “TrueHD light” on the AV receiver or soundbar will not illuminate. If a player is connected via HDMI and streams via bitstream, the viewer/listener will normally hear the appropriate substream of the TrueHD track. (Which substream depends, for example, on the number of speakers.) In this case, the display will rightly show “Dolby TrueHD” (or “Dolby Atmos”).