Unable to set Audio gain on Mac OS X

Anything and everything to do with DCP-o-matic.
prabu.venkat
Posts: 3
Joined: Mon Sep 01, 2025 9:44 pm

Unable to set Audio gain on Mac OS X

Post by prabu.venkat »

Hei!

Newbie here - firstly thanks for a lovely tool, appreciate it very much!

I have installed 2.18.23 on my macbook pro. I see that it is almost impossible to adjust the gain on the Mac OS X version (tested and works fine on my friend's windows box). Observation:

The true peak of my video is -0.81, and my goal is to get true peak near -7.
  1. when I try to do set a gain of -6, the spinner box becomes -6,0,0 and the true peak goes to -600.81.
  2. when I manually correct it to -0.6, the spinner reset to -6,0 and the true peak becomes -60.81.
  3. When I click on the spinner down button, it displays -0.5 and shows the true gain as -5.81, but as soon as I tab out of the spinner or click elsewhere, it becomes -5,0,0 and -500.81 respectively.
Screenshot video: https://app.screencast.com/nkKZGBSFpdgxM

How can I fix/get this done? I am also not really sure what -6,0,0 means or why so.

I have newly taken up tech responsibilty and have important screenings coming up, with no option other than my mac to work on. Will greatly appreciate any help!

thanks in advance!
carl
Site Admin
Posts: 2852
Joined: Thu Nov 14, 2013 2:53 pm

Re: Unable to set Audio gain on Mac OS X

Post by carl »

Hi,

That's not good!

Do you have a specific interface language set in the DCP-o-matic preferences?

What country/language is your mac set to?

Is a comma (,) your normal decimal separator?

Thanks,
Carl
Carsten
Posts: 3010
Joined: Tue Apr 15, 2014 9:11 pm
Location: Germany

Re: Unable to set Audio gain on Mac OS X

Post by Carsten »

I don't see that happening on my (old) Mac with 2.18.23. What is your Mac OS X version?

What if you adjust your gain using the down arrow to -6dB in 0.5dB steps? Also, try closing the audio graph window first.

Note, aiming for a specific TruePeak value as such does not make sense. True peak is a warning indicator only. You should aim for specific RMS or LUFS/LEQ values. But in this case, adjusting the level down -6dB in fact appears right to me (LUFS around -19 and LEQ(m) around 82db.

You could also try to rename your current version of DCP-o-matic and install an older version to see wether it makes a difference.

https://dcpomatic.com/old-downloads
prabu.venkat
Posts: 3
Joined: Mon Sep 01, 2025 9:44 pm

Re: Unable to set Audio gain on Mac OS X

Post by prabu.venkat »

@carl - I am on Sequoia 15.5 (M3 Max). We typically use "1.234.567,89" here, but I had setup English (UK) as the primary language.

Your suggestion about the i18n number format on the Mac was bang on -- when I changed it to "1234 567.89" (strangely it failed when set to "1,234,567.89" it failed, as it did for any other formats!).

Now, I am able to step up or down in 0.5 increments without problems.
Thanks a tonne!
prabu.venkat
Posts: 3
Joined: Mon Sep 01, 2025 9:44 pm

Re: Unable to set Audio gain on Mac OS X

Post by prabu.venkat »

@carsten
> true peak vs RMS/LUFS/LEQ

ah, I see! Thanks a bunch, I will learn more about this!
carl
Site Admin
Posts: 2852
Joined: Thu Nov 14, 2013 2:53 pm

Re: Unable to set Audio gain on Mac OS X

Post by carl »

Interesting, there have been bugs in this area in the past and it's tricky to get it right. Perhaps you could show me a screenshot of your macOS language/region settings, and the DCP-o-matic settings page, so that I can try to reproduce your situation? You could attach them here or email carl@dcpomatic.com if you prefer.

It definitely shouldn't be necessary to alter your language/region settings just to get DCP-o-matic to work!