Ocenaudio Audiobook Issue – RMS Value using AES17

Note – this is being reprinted from my email shared in early December 2020. If you are reading this well after that time, you might check to confirm whether this has been fixed. It was still present in Ocenaudio v3.9.5 for MacOS. You can receive those emails by signing up here.

If you are using Ocenaudio for Audiobook work, there’s an issue which has popped up. The “Statistics” function may be misleading you.

The newest version of Ocenaudio is now using the AES17 scale for measuring RMS – that is different from what ACX uses. There appears to be no way to turn that off or change it back. That means your audio may not be within spec and could fail the ACX technical check. (This change may have happened sometime in the past few months – not quite sure which version implemented this change.)

The “good” news is that AES17 is exactly 3 dB louder than the ACX-used-version (the “pre” AES17 version). That means if Ocenaudio showed your Total RMS value at -20.92 dB RMS, it would actually be -23.92 dB RMS as far as ACX is concerned. 

That’s why it’s helpful to have an outside tool to confirm your specs – a good reason to download 2nd Opinion to validate your settings. (Steven Jay Cohen’s 2nd Opinion is a great tool for audiobook mastering. It lets you check for header/tail and other things as well. A good tool to have in your arsenal).

As an immediate fix, recalibrate the numbers you aim for within Ocenaudio. Your Total RMS value range using AES17 would be -15 to -20 dB RMS (AES17). I’d aim at -17 dB RMS (AES17). 

The Peak value is not affected by this – it’s a different value and is still accurate. So if you are below the -3.0 dB Peak, that part would be within ACX spec requirements.

It’s frustrating not to be able to select which scale you use. If you use Ocenaudio in your production, it might help to let them know through the feedback portal on their site – https://www.ocenaudio.com/feedback

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