Basic Sound Monitoring?

Babblingo

Member
Hi,
Can OBS record four stereo sources to an 8-Channel .wav format while simultaneously recording their source video plus the combined sound from all four sources, in Stereo ?
 

AaronD

Active Member
No. Everything goes into a single file. But that file can have up to 6 separate audio tracks that each contains the number of channels that OBS is set to in Settings -> Audio. So you can set OBS to stereo and record a video with 5 audio tracks:
  1. Combined sound
  2. Component #1
  3. Component #2
  4. Component #3
  5. Component #4
The tracks don't mix - normal players only play one at a time - and Track 1 is usually the default to play. Any video editor that's worth using can pick out the individual tracks and mix them as you like.
Or if you must have a WAV, then Audacity with the FFMPEG plugin can take the video file and extract the audio from it.
(the same video editor probably does that too)
 

Babblingo

Member
Thanks Asron. That’s a nice surprise. Wow. I will try to
make a recording with four stereo pairs. Does this recording format have a spec?

Which video format(s) can or must be used ? I was goong to
use .mkv and afterwards run it into Shutter Encoder to convert to ProRes. I will see if it can export a multi-channel .wav and if not, use Audacity.
 

AaronD

Active Member
I will try to make a recording with four stereo pairs. Does this recording format have a spec?
Not a special one that I know of. Video files are not monolithic blocks of data. They have multiple tracks already. The picture is a track, the audio is a track, captions are a track, etc. You just have multiple audio tracks, is all.

Which video format(s) can or must be used ? I was goong to use .mkv and afterwards run it into Shutter Encoder to convert to ProRes. I will see if it can export a multi-channel .wav and if not, use Audacity.
Keep using MKV. It can be tempting to record directly to MP4, but the difference is crash resilience.

MP4 is designed to make playback cheap and easy. So it has headers that say what's coming. Of course, those headers can't be finished until the recording is, so if it's interrupted for whatever reason, without a formal stop, it ends up with a bad header. Without that header, it's really hard to recover anything, so you lose the entire file.

MKV is more like an old-school tape machine or film reel. If something goes wrong there, you still have everything up to the crash point.

Those are not formats though. They're containers. Formats are things like H.264 video or AV1 video or AAC audio or PCM audio. Almost any format can go in any container, with a few exceptions, so it's quick and easy to "remux" (as OBS calls it in the File menu) from the crash-resilient MKV to the easy-playback MP4...if you even need that. Pretty much anything that's worth using will take MKV directly.

For audio only, the WAV container requires PCM data, so you can set OBS to record PCM to make that conversion easy. PCM is lossless too, which makes it good for an intermediate file but not for streaming.
 

Babblingo

Member
I want to thank you again for taking the time to explain this so clearly. You are awesome.

I was reading up on .mkv and found this which confirms what you’ve written.
https://helpdeskgeek.com/mkv-vs-mp4-which-video-file-format-is-better/

I like your tape anology. That’s my era.

As for OBS, I need to clarify something about those 6 tracks available. Lets say I output a single stereo source to OBS track 1.
Will track one playback preserving the source’s left channel and a right channel in Stereo? (I think so)

As it turns out, I’m having lots of difficulty bringing four separate live sources (internet streams) simultaneously into this version of OBS.

I had a nice 2x2 quad working in OBS a few years ago but had not paid any attention to isolating each source’s audio.
I was amazed at what I could do visually with the Move plug-in.

I’m gonna try just using four local stereo sources and concentrate on the audio recording track assignments, for now.

Thank you!
 

AaronD

Active Member
I like your tape anology. That’s my era.

As for OBS, I need to clarify something about those 6 tracks available. Lets say I output a single stereo source to OBS track 1.
Will track one playback preserving the source’s left channel and a right channel in Stereo? (I think so)
Yes. That's where the analogy breaks down a bit. Tracks in OBS have multiple channels in them, according to what it's set for in Settings -> Audio.

If you imagine a 4-track tape machine, that's closer to setting OBS to 4.0 and using a single track. Multiple tracks in OBS is like multiple synchronized machines.

As it turns out, I’m having lots of difficulty bringing four separate live sources (internet streams) simultaneously into this version of OBS.

I had a nice 2x2 quad working in OBS a few years ago but had not paid any attention to isolating each source’s audio.
I was amazed at what I could do visually with the Move plug-in.

I’m gonna try just using four local stereo sources and concentrate on the audio recording track assignments, for now.
The track assignments are in Edit -> Advanced Audio Properties, or the gear icon in the Audio Mixer dock. In there, you have a somewhat confusing drop down with 3 options:
  • Monitor Off sends it to the Track selection only, which is right there.
  • Monitor Only (mute output) sends it to the only physical output that OBS has, and not the Track selection.
  • Monitor and Output sends it to both, post-fade.
You might think of those two sections together as the routing buttons on a physical console. It's a little weird (why is there a dropdown, and not a single checkbox for the Monitor like there is for each Track?), but not too hard to get used to.

Then in Settings -> Output, you can set it to Advanced mode, and then choose which Track(s) to record.
 

Babblingo

Member
Aaron, I’m glad you are going into a full explanation pf OBS sound. I have been very lost on audio monitoring in Win 10 Pro since forever, so OBS audio has been an added mystery.

I need to learn how to monitor OBS, hearing the volume changes I make in OBS’ Mixer…in real time, if possible, without
also hearing anything else from my pc.

I’d prefer to do it without adding more peripherals to my pc.

My monitoring life got much better after getting a Yeti USB mic, with its analog output jack.

( I stopped using the front or rear mini jack outputs on my workstation.)

So with that all in place, how could I monitor ONLY OBS instead of only Desktop Audio? Would I simply take the trouble to change my pc’s Audio > Settings before sitting down to use OBS? I’m not sure how I would do that though but it should be posdible, I think.

*At one point I had licensed those Virtual Cables, so I do have that software option, I suppose, if there is an overall OBS setting to direct its output into one of them.

Then I ought to be able to patch that Virtual Cable into the Yeti in Win Audio Settings.

That’s where I stop and scratch my head… but please don’t feel obligated to keep replying, You’ve already given me the basis I need to learn all this and I really do not want to ruin your day. or weekend.

Thanks and know that you have helped alot!
 

AaronD

Active Member
I need to learn how to monitor OBS, hearing the volume changes I make in OBS’ Mixer…in real time, if possible, without
also hearing anything else from my pc.

...

how could I monitor ONLY OBS instead of only Desktop Audio?

...Virtual Cables...

...I ought to be able to patch that Virtual Cable into the Yeti in Win Audio Settings.
If you're referring to this:
then I think you actually want one of these (2 different sizes of the same thing):
*Then* you can connect a virtual endpoint to a physical one, somewhat like a pared-down mixing console.

To not hear anything else in your 'phones, just set Windows' output device to something else. Like maybe one of the virtual speakers that Banana or Potato provides, and then it's in the mixer. Then you can send it to OBS through a virtual mic if you want.

Or if you want a dead-end, you can send Windows' audio to the built-in device that you don't use. Your 'phones are driven from VM, which doesn't use that selection.

Keep in mind though, that each virtual connection is its own trip through Windows' audio system, which is not exactly known for being particularly fast. Lots of gamers can't use Voicemeeter because the barely-perceptible delay of that additional trip throws them off.

---

If you're really doing something serious with OBS, I'd recommend swapping out Windows itself for something that is actually designed for the job.

I use Ubuntu Studio Linux, which has all the support of the awesome Ubuntu community (the most popular flavor of Linux by far, among non-technical users), and is designed specifically for creatives. It has a TON of that sort of apps preinstalled and already working, so you don't have to beat your head against a simple problem that you can't find on an unfamiliar system - OBS is one of those apps - and the task scheduling under the hood is much better too, so live media stays responsive. I've heard of people running a live music festival on UStudio and its preinstalled DAW (Ardour) instead of a console...

Then use the DAW for your audio work, both recording and feeding OBS *exactly* what goes in the video soundtrack. OBS, then, is completely silent - no audio sources at all - except for that one feed that the DAW gives it, and it passes that through completely unchanged. If you still want the separate soundtracks in the video file, then you have that many separate connections from Ardour to OBS, all of which are fully processed in Ardour and simply passed through in OBS. (one source for each, with appropriate routing)

If you still need to control the audio based on what's happening in OBS, like scene changes or whatever, then you'll need to recreate that explicitly. The Advanced Scene Switcher can detect pretty much anything, and do pretty much anything in response to it, including OSC messages (Open Sound Control) to Ardour in response to scene changes.
Since OSC is just a single message that produces a step-change somewhere, I have mine working indirectly. One more channel strip in the DAW has a 20kHz sinewave generator, followed by several Aux sends that the OSC messages control. Those Aux sends connect to the sidechain of a gate on each of the signals that I actually want to control. The timing controls of each gate, then, create a fade instead of a cut-on/off.

For that and other DAW plugins, I really like the LSP series, which is also preinstalled with Ardour on Ubuntu Studio:

please don’t feel obligated to keep replying, You’ve already given me the basis I need to learn all this and I really do not want to ruin your day. or weekend.

Thanks and know that you have helped alot!
I'm here because I like explaining things. Keep going! :-)
 

Babblingo

Member
Hi Aaron,
Thanks for the details on Banana and all the Ubuntu info.

I finally was able to operate my PC to monitor volume changes in the OBS Mixer. I can listen to OBS Program output after changing OBS Monitoring Device to the analog out jack of my Dell display— got a stereo mini cable feeding my headphones. That’s tbe good, but I see that my ISP is no longer permitting 4 simultaneous, different channels. So I doubt I’ll be able to set up for a 2x2 quad. Bummer. This was do-able 4 years ago. I’ll get back to ya if any workaround is found. Take care and thanks for all!
 

AaronD

Active Member
my ISP is no longer permitting 4 simultaneous, different channels. So I doubt I’ll be able to set up for a 2x2 quad.
What are you actually doing?

I was thinking something along the lines of a live band or conference or local gaming session. Something that has all of the sources local already, and you want to at least preserve what they were and possibly mix them later, in addition to the live production in the moment. No?
 

Babblingo

Member
Hi, well that’s certainly the right question! But
I just can’t answer it properly at this time.
I’m slowly building towards a remote, collaborative music/video based project… and it is a long way off. (If I ever get around to it.)

Thank you again for your supportive ideas and links about Ubuntu.
 

AaronD

Active Member
a remote, collaborative music/video based project…
I suspect your biggest problem with that, once you get all the streams working in the first place, is going to be latency.

If you're running on public internet with no special priority (expensive!), then you're going to lose data and resend it automatically. It takes time to figure out that something is not going to arrive and request a resend, with the same chance of *that* getting dropped too, and so you need a buffer that is several times that length so that a packet that finally arrives can slot in before it's needed. That buffer has units of time (or can be converted to time), and is the primary contributor to the amount of latency/delay that you have between when something actually happens and when you see it on screen.

If you can shrink the buffer, then you're closer to real-time, but you also risk it breaking up. Live music needs to be pretty tight to even work at all, let alone well. If everyone's in the same place, or has an actual dedicated connection, great! But if even one is across the internet, I don't think it'll work at all.
 
Top