Bug Report OBS Clipping Audio at -6db

[Nish]

@Suslik V Alright so I did a couple of tests and found out that whatever OBS is doing differently than other programs, it doesn't seem to matter in the end when it comes to actual perceived loudness. Here's an article if you're not sure what loudness is: https://transom.org/2015/the-audio-producers-guide-to-loudness/

I tested lossless vs lossy and that didn't seem to make a difference, the big test is comparing the audio from an OBS recording to the audio from recording in adobe audition (downmix to mono vs no downmix didn't make a difference either).

Here is the loudness level from an OBS recording (we're looking at the number under LKFS and a lower number is louder):

And here is the loudness level from my recording in audition:

Keep in mind that OBS outputs a stereo signal by default unless you choose otherwise (my mic input is going into OBS mono so it shouldn't matter).

As you can see they're the exact same besides maybe half a second of recording time from when I tabbed to OBS to stop the recording. I believe this means there's no reason to worry about the peak meter not reaching full in OBS, I'm not exactly sure what's going on there or why it occurs but it seems to be recording your mic at correct levels.

Not sure if I missed anything, let me know if I did.

 

[Suslik V]

@Nish what shared mode running your recording device (Windows Sound, Recording devices>Properties>Advanced tab>Default Format for shared mode of the device)?

To compare something, you need to meet same conditions, otherwise it makes no sense. You cannot compare 2 channels audio to 1 channel audio.

 

[Nish]

@Suslik V 1 channel, 16 bit, 48khz. I made sure to use the same settings in both so don't worry about that. The reason one is stereo and the other is mono in the screenshot is because most people will be outputting stereo from OBS even if the mic input into OBS is mono (I tried outputting mono from OBS as well and the result is the exact same).

 

[Suslik V]

@Nish If you can meet all conditions what bothering you then? Are you complain that OBS Studio's Lossless audio recording differs from lossless - that it changes levels or whatever - and there is some bug in the Studio?

Please, check your Default Format for shared mode settings - if it is allowed to set stereo mode, please set it up. It will be much easier for you to mix tracks with other sounds (I assuming that all your desktop playback devices configured to use stereo mode too).

Try to avoid re-sampling of the audio data when you configure shared modes of the Windows devices and OBS Studio's Audio itself.

 

[Nish]

@Suslik V You're misunderstanding my posts, my testing concluded that there is no issue with the way OBS handles audio signals. People in this thread (myself included at the beginning) are worried about peaks seeming to be different, and while they do look different, there is no difference in actual loudness - so it's a non issue in the end unless you really want your waveform to look a specific way.

 

[Dildano]

I teach audio production. OBS, regardless of codec, or any of the settings described here on this thread or elsewhere, boosts it's input by 6dB. This is with no filters, and literally days of trying everything and searching all forums. Testing with mics is a terrible standard. Here is a 0dB sine wave. The top track is at 0dB, and it is hard clipping the sine. The bottom track is at -6dB. We can see that on the input side of OBS it is taking whatever it gets and boosting by 6dB, as the -6dB drop results in a pure sine.

 

[Dildano]

Workaround found: I just found that you could just click on the audio toolbar menu next to volume control, filters, add "gain", use 3 dB or maybe higher.

Re-tested with OBS-studio custom ffmpeg output, AVI using audio: pcm_f32le. Same problem, nothing to with AAC encoder.

With OBS-studio using stereo mode, the green bar on the Mixer for mono microphone and other mono, 1 channel inputs doesn't go all the way to full bar, until a filter "gain" is added with +3 db.

Nearly all analog audio input device like to clip the audio to fit to a full range of 16 bit integer. But then, OBS-Studio or somewhere is making 1 channel mono inputs quieter. This makes it appear it was clipped well before the full range is reached. OBS-Studio is not allowing an easy full volume on mono inputs like USB microphone, until a filter "gain" is added.

Dropping by X amount on your output and then boosting by X on your input is not a workaround. This raises your noise floor by this amount.

 

[Dildano]

Deleting all sources revealed a hidden fader underneath the fader that was there. It was not showing 2 inputs. This GUI bug makes it look like there is only one audio source when there may be mutiple. Checking to see if this fixes issue.

 

[prenetic]

Adding to the other explanations, this most commonly seems to occur when there is a mono input over a stereo output (left or right channel only), but can present itself in other multi-channel configurations as well.

When I have "Mono" unchecked for the microphone in OBS only the left channel shows a signal (as expected with my configuration), and it peaks at the same amplitude as any other application I measure with.

When "Mono" is checked I've found OBS stonewalls at -6 dB as if I had a limiter set, but the signal is correctly mixed to both channels. To compensate I just add a +6 dB gain filter to my microphone filter chain so the amplitude is realigned.

Other applications that have similar functionality exhibit the exact same behavior, Audacity for instance shows the same -6 dB change when switching from stereo to mono for the microphone. More information in this phenomenon can be found below.

Audio: Mono vs. Stereo Levels | Larry Jordan

 

[Frogging101]

I don't know if this is the problem others are having, but in my case my clipping issues were caused by my own ignorance.

See that Mic/Aux under Sources? It's doubling the mic audio since we already have that source enabled globally, in the Mixer. That produces +6dB. Removing that source from the scene solved my issue.

 

[3ncoder]

Adding to the other explanations, this most commonly seems to occur when there is a mono input over a stereo output (left or right channel only), but can present itself in other multi-channel configurations as well.

When I have "Mono" unchecked for the microphone in OBS only the left channel shows a signal (as expected with my configuration), and it peaks at the same amplitude as any other application I measure with.

When "Mono" is checked I've found OBS stonewalls at -6 dB as if I had a limiter set, but the signal is correctly mixed to both channels. To compensate I just add a +6 dB gain filter to my microphone filter chain so the amplitude is realigned.

Other applications that have similar functionality exhibit the exact same behavior, Audacity for instance shows the same -6 dB change when switching from stereo to mono for the microphone. More information in this phenomenon can be found below.

Audio: Mono vs. Stereo Levels | Larry Jordan

I discovered this just some minutes ago but I think, this is new on my computer.
Last time I opened OBS it was peaking at mono at 0dB

This should be fixed and I will report it on Github because when there is a mono button the boost can be add automatically in the programm