Logic Pro X Dolby Render

Scott Borel (Customer) asked a question.

January 27, 2024 at 11:52 PM

I'm wondering if anyone working with Logic Pro X has noticed the Binaural Dolby Render sounding severely degraded? I just got the Dolby Atmos Renderer and routed an Atmos Logic Pro X Project to it and, for the first time, I can hear what proper Binaural Dolby Rendering sounds like. I'd like to stick to just mixing Atmos using the integrated Logic Pro X system if possible, so if anyone knows why Logic Pro X's Binaural Dolby Render might sound degraded, please let me know. Thanks!

The Dolby Atmos Renderer

BennettS (Dolby Labs)
2 years ago
Hi,

Can you provide some more information on your workflow (how are you getting audio to/from the Renderer, what tools and plug-ins are being used, and any inserts you may be using)?

-B
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- Scott Borel (Customer)
  2 years ago
  The degraded sound is audible when listening to the Dolby Render of any project in the integrated Logic Pro X Dolby Atmos Renderer. I thought maybe I was crazy and that Dolby Atmos's Binaural rendering just sounds like that until I routed previously made Atmos Mixes from Logic Pro X into Dolby's Dolby Atmos Renderer software and heard the difference in the Binaural Render coming from that software. I'll link some audio files of a stereo render of some audio, the Logic Pro X integrated Dolby Atmos render of the audio, and Dolby's Dolby Atmos Renderer software's render of the audio. I mainly noticed a very sharp boost in high frequencies in Logic Pro X's Dolby Atmos Render. This degradation I'm hearing is with no inserts/plugins before or after Logic Pro's integrated Dolby Renderer, and it sounds like this in any project, new and old. When doing an EQ match using Pro-Q 3 between the Stereo Render and Logic Pro X's Dolby Render of the audio linked here, the Logic Pro X's Dolby Render adds a 18.5db boost at 18khz, a 7db boost at 12khz and an 11.5db dip at 9.3khz when compared to the Stereo Render! The EQ match between the Stereo Render and the Dolby Render from Dolby's Dolby Atmos Renderer software shows some frequency differences too, as expected, but they're significantly subtler differences. The biggest boost in this EQ match is 3.5db at 12khz and the lowest dip is 5.5db at 17khz. I don't understand why Logic Pro X's integrated Dolby Render creates such intense tonal changes. I should also mentioned I've experienced this degradation across multiple version of Logic Pro X.
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  - Scott Borel (Customer)
    2 years ago
    Audio files mentioned: https://drive.google.com/drive/folders/1glocua7u1fntRAPyUCiApfqlWp4M7QDK?usp=sharing
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  - BennettS (Dolby Labs)
    2 years ago
    To piggyback on Sam's post below, binaural content is renderered using HRTF (head-related transfer function) which can change the frequencies of content depending on position, binaural metadata settings used, and object size. It should be noted that these are not specific frequency cuts/boosts applied in a static fashion, but as mentioned are dependent on the factors listed above.
    
    The difference you are hearing between Logic and the Renderer is most likely due to the new rendering processes updated in v5.2 of the Renderer (see this FAQ for more information: https://dolby.my.salesforce.com/sfc/p/700000009YuG/a/4u000000B3IM/yYycsBj3hEI8M.3T.tbv5L5gwKVPDcV7uwF2wcDdgQE). Logic has not yet adopted the latest Rendering processes.
    
    -B
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Sam H (Self Employed)
2 years ago
I could be wrong, but once monitoring in binaural (Dolby Atmos Binaural or Logic/Apple Spatial) the input object/bed sound is filtered through an HRTF frequency response. This will have peaks and troughs compared to the Stereo because HRTF filtering is either adding or cutting db from 2k to 20k in several bumps. This is the big complaint with Binaural, it generally is a degradation in sound quality compared to the Stereo when measured like-for-like. imo Engineering best practice would be to allow the Engineer to decide how the HRTF and Binaural filtering works, because having Apple have their interpretation of Binaural being different than Dolby's and then Stereo being without an HRTF at all in headphones, it's a bit of a mess imo. Hopefully one day all Binaural HRTF is possible to switch off and can be engineered into a dedicated headphone mix itself instead, that is best practice really.
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