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Atmos Mix re-rendered as LtRt is clipping and sounds bad


We are doing an Atmos Home theater mix and we are starting to test printing the mix but we are getting poor quality 2.0 Re-Renders using the production suite.

Is there a way to adjust level trim for Re-Renders or is there a limiting functionality of the Re-Renders that I can access? The 5.1 Re-Render seems to be as expected and this issue is only present in the 2.0 Re-Render.

I know that there are options to specify which type of LtRt to use but changing this option does not help and the other options actually sound worse. I have not done Direct Render because the stereo file I need to deliver must be able to be decoded back into 5.1

Can you please help guide me to any settings I may have missed or possibly provide some insight into why the 2.0 Re-Render is clipping so much when the full Atmos mix does not? Thank you! 


Hi Nathan,

Try enabling Spatial Coding Emulation in preferences/processing.   This also enables the limiter used in Spatial Coding which should affect the stereo re-render as well.

Also note that when direct render is not use the stereo is derived from 5.1 which is derived from a 7.1 render.   The 5.1 downmix mode may have an impact on the stereo downmix and is worth experimenting with.

Are these artifacts audible when setting the speaker monitoring to stereo or only on the re-renders?   Are the re-renders realtime or an offline export?   Is there any difference on importing an offline re-render vs realtime that could point to something in the signal path?

If all else fails you may need to use a VCA in your session to attenuate the input to the renderer but hopefully the Spatial Coding Emulation limiter will help.

Thanks, Adam

Hi Nathan,   Actually the SC limited should already be applied.   Worth noting that the if your mix is mastered with the Mastering Suite vs the Production Suite there are 5.1 downmix trims that can be customized.   These affect monitoring and are also written to the master file for downstream encoding.

Hi Adam, 

We recorded the 2.0 Re-Render real time - recording in Pro Tools from the suite. Yes, we do hear the artifacts still when we listen to the mix with the speaker monitoring set to 2.0 in the suite.

I will try changing the 5.1 Re-render downmix mode when I can access the mix this evening, and I will also see if turning on Spatial Coding Emulation helps and report back. I can also make a master, make offline Re-renders and import them if you think that will produce a different result

Thank you for the help with this!

Hey Adam,

Thanks for the added info. 

I was unable to produce different results without altering the mix. As a workaround we are currently using the 5.1 Re-render and feeding that into a separate LtRt encoder insert and it is producing good results.



Is there any update on this Thread? We are experiencing the same problem using the Renderer 3.3. We are Offline Rendering & then exporting the 2.0 but getting glitches & clicks on our the file. The LFE Limiter is enabled which appeared to help initially but is still a problem.

No changes made as yet.   Have you auditioned the 2.0 Direct render mode vs a 5.1->2.0 downmix.   If this is not appealing or doesn't solve the issue then you choices are to remaster with the session output attenuated or downmix externally.    We are looking into remedies for this.  



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