How to select audio inputs?

[vinnyvincentinversion]

I have been experiencing inconsistent operation with OBS and my MOTU M4 for months.

In the past, OBS would only allow me to use inputs 1 and 2, inputs 3 and 4 were always completely disregarded by the application. There is no way to select any inputs, just which interface, and it would always only receive signal from inputs 1 and 2. This was a problem, as I often wanted inputs 3/4 to go to OBS, but had to move cables around to instead send signal to 1/2 because of that very limitation.

Knowing this, today I tried to record a video with 3 channels of audio. My intent was to run 2 channels into OBS from M4 inputs 1 and 2, and record my 3rd mic from input 3 into another application (Ableton Live) and put it back together in editing.

Except today when I open OBS, it is now suddenly taking input from all the interface channels at once, and I have no way to record channel 3 audio separately, as OBS is now summing channels 1 and 3 and outputting it all as 2-channel stereo.

I can't make any sense of OBS's audio settings. Under Preferences>Audio there are all these "Global Audio Devices" but they are all disabled. Some of them list M4 as an option, others do not. I don't know what any of it means, or why I have functioning audio at all with everything disabled.

The Properties under the M4 interface only give me the option to select between "M4" and "Default," but there is seemingly no change in operation between the two settings.

Advanced Audio Properties for the MOTU gives checkboxes for channels 1 through 6, but what does that mean? It apparently doesn't correspond to inputs, because I get no change in operation regardless of which boxes are selected. No settings cause anything to change.

CanIi try 2.1 audio? Will that let me record a 3rd channel of audio directly into OBS? I then have to figure out how video files deal with audio more than 2 channels and how i can seperate it all for editing.

Can anyone help point me in the right direction here? How do I make this work?

Is there a user manual for this app? I looked through all the support stuff for audio I found on this site but none of it was relevant.

Thanks for any help or direction.


I just posted a long post about this and it immediately disappeared, sorry if there is another one of these somewhere.

 

[AaronD]

OBS can't use audio devices that have independent inputs. It only understands a single source per entire device, and the channel count must indicate the surround format of that source/device. No other option. And it mixes down that surround format into whatever OBS is set for.

If OBS is set to stereo, for example, and you try to use an 8-channel interface, then those 8 channels get mixed down according to the rules for 7.1 to stereo: front corners, sides, and back corners mix together in varying amounts to make a single stereo pair, center goes to both, and LFE disappears. THEN you get to play with that mess.

Don't use multichannel interfaces directly with OBS. Use a different app to make sense of it, in which case you might as well do ALL of your audio work over there so that OBS has only one audio source at all, and that's for the final finished soundtrack to pass through completely unchanged. Or, use a bunch of separate smaller devices, so OBS can have a dedicated device per source like it wants.

One of my rigs uses a DAW (Ardour, Ableton, FL Studio, Studio One, Reaper, etc.), and another uses a physical console. For both, OBS has only one audio input at all, for the final soundtrack, that exactly matches the channel count that OBS is set for.

 

[vinnyvincentinversion]

I wish this explained why my channel 3/4 NEVER worked in OBS before, yet now is ALWAYS on, apparently. It also makes me even more confused about the existence of all these seemingly useless audio options that don't appear to do anything. Why are those settings even there if they serve no real function and OBS's audio capability so limited?

All the surround stuff is over my head, never used it before and don't understand it all tall, was just floating it as a possibility but it still doesn't make sense so I guess not.

This is also problematic since this change in OBS's operation now means that any time I record or steam, OBS will now also be picking up the stereo output of my mixing console which I keep hardwired to the M4's inputs 3/4. I'm not going to be able to monitor without creating a feedback loop or something, no? Not sure how I will get past that.

With what version did this change occur? If I can't select inputs I would just prefer go back to how it used to be ignoring those inputs entirely.

I don't actually know why I didn't think to just record all 3 channels of audio into my audio software, I think it was for ease of sync. I might need to incorporate a makeshift clackboard, is that a thing people do in these instances?

Thanks.

 

[AaronD]

For the makeshift clapboard, you can just clap your hands. Lots of people do that.

But if you're using quality enough stuff that the latency is constant, you should be able to fine-tune it once and be done...well...until you change something at least. If you bring all of your raw sources into the DAW, not OBS, do all of your audio work in the DAW, and only give OBS the final soundtrack, then I think the latency should be constant even if you do change your mix or track count.

As long as I've been taking it seriously, OBS has always been this way, so it's been at least a couple of versions. I thought it was always like this, as a holdover from the stereotypical bedroom streamer that it was originally designed for, who has a USB or analog-soundcard mic, and a surround-sound game. All of that is a single source per device, and he'll be confused by anything else. (Why would anyone want to split up a surround sound game and remix it?) So those of us who do something other than games, need to work around an audio system that is designed almost exclusively for that type of gaming rig.

The devs are aware of how bad it is, and they want to fix it. But they're still in the early stages of figuring out what to replace it with, so as to keep it maintainable for a long time in the future. In the meantime, I don't expect much of anything to be fixed. It'll plateau here for a while, and then some future version is going to break *everyone's* rig, because I don't think the present system can be compatible with anything sensible, as I see it having learned on pro gear.

When I used an 18-channel digital mixer for a last-minute outdoor show, I ended up mapping the first 2 channels on USB to my stereo soundtrack and the other 16 to silence, in the mixer itself, not OBS. Then it didn't matter how OBS wanted to downmix those 18 channels into stereo, because the first 2 channels are pretty much universally the front corners, and that plus silence on the rest of them is still the stereo pair that I wanted. Better, though, would be to set the mixer to 2-channel instead of 18-channel, or use a separate 2-channel device instead of anything bigger.

 

[LaffRaff]

One of my rigs uses a DAW (Ardour, Ableton, FL Studio, Studio One, Reaper, etc.), and another uses a physical console. For both, OBS has only one audio input at all, for the final soundtrack, that exactly matches the channel count that OBS is set for.

Are you saying to pass my mixer source audio channels (Focusrite Clarett 8 Pre, 8 channel) into something like Adobe Audition, and then have OBS take in the Audition Source?
Yes, I've noticed that with my thunderbolt connected mixer, OBS only recognizes the first 2 channels (which, ironically, I was not using. Only using channels 3-8, so for the longest time couldn't figure out why the focusrite source wasn't giving any signal..) but now that I've learned the limitations of OBS, how can I pass channels 3-8 on to OBS?

Even within my Focusrite software, I cannot see how to route the channels into channels 1 & 2, if at all. But I do notice that this is not an issue for other (DAW, am I using that right here?) i.e. Quicktime, Zoom, etc. They all take in my focusrite inputs clearly. OBS is so close!

I've seen mention of software like "Black hole" which can make different audio routing inputs, but I think the channel limitations of OBS will still 'see' 8 channels through black hole and only recognize the first 2 again. I want to 'mix' all 8 of my channels into 1 source and direct that to OBS. Are you saying I could that in Audition? or as you mention - Ardour, ableton, etc which I'm not familiar with. Thanks!

 

[AaronD]

Are you saying to pass my mixer source audio channels (Focusrite Clarett 8 Pre, 8 channel) into something like Adobe Audition, and then have OBS take in the Audition Source?

Yes. Or any other DAW. Prices vary wildly, and even include free forever, with not much difference in our required functionality as I've seen. Other functions maybe, but not live mixing with our typical channel counts.

how can I pass channels 3-8 on to OBS?

Put something in between, like a DAW.

i.e. Quicktime, Zoom, etc. They all take in my focusrite inputs clearly.

Not every app that uses audio is a DAW. A Digital Audio Workstation is pretty much a complete sound studio, and that's all it does. It can record and play back many separate tracks at once, in sync, mix live like a physical console, mix a multitrack recording and record the result, create its own sounds to add to that mix, etc., etc.

We're just using it here for the live mixing part, and *maybe* an independent audio recording or playback.

OBS is so close!

So close, yet so far. That's been a chronic complaint for a long time. This and other things would seem like "simple fixes", but it's such a mess under the hood that "backwards compatibility" is practically a freeze. It needs to be completely redone - intentionally break everything and do it "right", whatever that is - and that takes a lot of time and effort to figure out for as varied use-cases as we have now.

So I wouldn't expect OBS's audio to change at all for perhaps a few years, and then EVERYBODY will have to rebuild their rigs from scratch. Or at least the audio side of them.

I've seen mention of software like "Black hole" which can make different audio routing inputs, but I think the channel limitations of OBS will still 'see' 8 channels through black hole and only recognize the first 2 again. I want to 'mix' all 8 of my channels into 1 source and direct that to OBS. Are you saying I could that in Audition? or as you mention - Ardour, ableton, etc which I'm not familiar with. Thanks!

I'm not familiar with how Black Hole actually works, but what it receives and what it provides are technically independent of each other. Whether it's written to take advantage of that is a different question. Nothing says that an app must preserve the formatting that it receives.

Multichannel audio is not a single data stream that can't be broken up. It's often handled that way between apps and devices, but inside of each thing, it's a bunch of parallel streams that each has only a single channel. To an app developer, each channel can go anywhere you want independently, with no restriction on that. Split up, mixed together, packaged into a new stream to send out, etc. Apps that keep them together, like consumer players, are only programmed like that, not because anything says so beyond consumer convenience.

The reason that OBS doesn't "just work" in this area is also not the result of any particular rule, but "technical debt" from a now-ancient developers' decision that has become entrenched.

 

[AaronD]

At one time, there was an ASIO plugin for OBS:

OBS 30 does not support the OBS ASIO plugin

Just joined up to help out with anyone else having issues with this. I use the obs asio plugin to have more control of my interface's IO. I use a Focusrite Clarette+ 8pre (which has a slew of issues on it's own). All the mic/line inputs are coupled together into stereo pairs when viewed in...

obsproject.com

ASIO bypasses all of Windoze's audio mess (it's the only operating system that needs that; Mac and Linux are fine as they are), and talks directly to the hardware, and that plugin used to create its own source that you could choose device channels inside of. So in a twisted sense, Windoze became the only OS that OBS *could* choose device channels on.

The original seems to be abandoned and taken down, and the new one isn't ready yet??? Not really sure on any of that, but it hardly matters here on the Mac side of the forum that doesn't have ASIO anyway.

 

[LaffRaff]

Yes. Or any other DAW. Prices vary wildly, and even include free forever, with not much difference in our required functionality as I've seen. Other functions maybe, but not live mixing with our typical channel counts.

And how do I do that? On the Audition side, how do I set it up to output to OBS. I can get the sources in, pro problem, we did it with a podcast, but now I want (loopback?) it to go from audition to OBS. Or rather, what do I point OBS to as the audition audio source?
Thanks for the replies!

 

[AaronD]

And how do I do that? On the Audition side, how do I set it up to output to OBS. I can get the sources in, pro problem, we did it with a podcast, but now I want (loopback?) it to go from audition to OBS. Or rather, what do I point OBS to as the audition audio source?
Thanks for the replies!

That depends a LOT on your choice of tools to do it, and there are lots of those! I've never been a Mac guy - grew up on Windows 98 and XP, waffled between Windows 7 and Ubuntu Linux, then Windows 10 and Ubuntu, and ended up staying on Ubuntu Studio when Windoze decided it would no longer update on this perfectly good live media hub and daily driver that now runs Linux exclusively - but the vast majority of questions here are about universal fundamentals, so I still answer those. When it finally starts talking about actual OS-specific stuff, I really don't know Mac very much at all.

The basic idea is almost the same regardless. A loopback device, as a general concept, is a virtual speaker and a virtual mic, that any app(s) can use as if they were separate physical devices. Whatever you send to that virtual speaker, appears in that virtual mic. The concept itself has no restrictions on how many separate speaker/mic pairs you can have, how many channels each has, etc., but of course each specific implementation has its own somewhat arbitrary decisions that you have to work with.

I would not be surprised if some DAW's saw this sort of thing coming, and included their own loopback devices. Not all do. See if yours does, and if so, see how that specific one works. If it doesn't, there are standalones that you can use too, but again I'm not really a Mac guy specifically, so I couldn't tell you what names to look for.

Most OS's have built-in loopbacks for each output device (speaker), both physical and virtual. That's how the Desktop source in OBS works. So that might be an option too: send the DAW to an audio device of some kind, and pick that up with OBS's Desktop source.