Hi, we are trying to get our audio levels balanced properly and seeing a discrepancy between both metering levels and LUFS-I when comparing what is shown in FMOD Studio while connected to the running game and what is shown in OBS metering and subsequent LUFS analysis.
In one instance, LUFS-I was about 3 units louder in the captured audio vs FMOD Studio.
In this screenshot you can see how metering in FMOD Studio is around -30 dB, while metering in OBS is around -18 dB. I’ve checked all of my system settings and cannot find anything that would be boosting the signal. My teammate is seeing similar results on his machine.
What might be the cause of this?
This is with Unreal 5.6 and FMOD 2.03.13 running a Steam Windows build.
Hi!
It’s difficult to know what exactly is the cause of the discrepancy, but it’s likely that the OBS’ metering isn’t using the same scale or measurement. OBS’ metering is slightly different from Studio’s. While Studio has peak as the horizontal line above the filled in RMS bar, OBS has 3 elements: the horizontal line is the maximum level reached, the filled in bar is the peak, and the black line on the filled-in bar is the RMS measurement. From what I can see in your screenshot, Studio’s metering looks about in line with OBS, though I can’t account for 5.1 being summed to Stereo, or for LUFS measurements since there isn’t one for OBS in the picture.
You can see more on OBS’ audio metering here: Audio Mixer Technical Details | OBS
Otherwise, there’s a few other things that could be contributing:
- Studio is metering in 5.1, while OBS appears to be metering in Stereo. You may get more a accurate comparison if you change Studio’s format before the loudness meter
- If the FMOD system’s output level is too loud and FMOD_INIT_CLIP_OUTPUT isn’t enabled, the output signal will be attenuated (unlikely to be the issue, based on your picture)
- There may be some attenutation coming from the OS’ audio driver that isn’t being accounted for
Ah, thanks for the clarification of the differences between OBS metering and FMOD Metering, I wasn’t aware of that.
After some more testing with Youlean Loudness Meter 2 on the OBS audio capture, it appears to be the case that the loudness difference is being caused by the mixdown to Stereo as you suggested it might be. When I set the Master Bus explicitly to Stereo and then do a play session on a build with FMOD Studio connected with Live Update and OBS monitoring at the same time, I see that the LUFS-I reported in FMOD Studio exactly matches what is reported in Youlean Loudness Meter. So, that’s a relief to have identified that.
That said (and I can make a separate thread for this if you like), when turning down the Fader Volume on the Master Bus and Resetting the FMOD Loudness Meter, I discovered that the meter seemed to be displaying some old data that wouldn’t clear out, though the animated meter looks to be correct. Even after closing FMOD Studio entirely and reopening, it continued to report -18 LUFS-I even as Youlean Loudness was reporting in the -30’s. I’ve attached a video so you can see what I’m talking about.
Thanks for the video demonstrating the issue. A couple of questions:
- Were you playing audio into the loudness meter for an extended duration before attempting to reset it?
- Do you receive any warnings or errors in the Console at Window → Console → Logging?
- Are you able to reproduce the issue in a different project that isn’t connected to source control? For example, the examples project that ships with Studio? You can generate an examples project from Help → Welcome → Create New Examples Project.
