How To Mix Audio for Commentary Without A Physical Mixer

As I mentioned when discussing this year's SXC, I had a large pile of issues with the audio for the anime stream. These would all have magically disappeared if I had a proper physical audio mixer, but I am currently short on the cash to make such an investment. In my quest to work out what the purely digital options are, I discovered that what meagre documentation exists is horribly obtuse. As a result, here is a simple guide to setup the following:

 - Audio picked up by Open Broadcast Software
 - Two microphones picked up by Open Broadcast Software
 - Game Audio through both commentators' headsets
 - The microphone of whichever headset you're not wearing through the one you are wearing, allowing for both commentators to clearly hear when and what each other are saying.

Step One: Acquire Virtual Audio Cable

You can do so right here. It costs $25US if you don't want the ability to complain to the dev if something goes wrong. Less if you sail the high seas. This is the only investment we'll be making.

After installing VAC, right-click on your volume icon and take a look at your Playback and Recording devices.

You should see a new device in the listings called Line 1. This is essentially a big connecting cable we're going to bash several audio inputs into so OBS can receive more than its customary two.

That's it there at the bottom. It's in the Recording tab as well.

The setup we're going through requires two, so let's fire up the configuration tool!

Run it as an Administrator, just to be safe.

The only part of this configuration we care about is circled in red. Simply increase the number of Lines to whatever you want (in our case 2) and click Set. You should see it appear in the white area below. Then check that it's in your Playback/Recording Devices.

Magical!

Step Two: Preparing your Virtual Cables

Obviously we need two headsets. The two I am using are a mix of Triton and Logitech. We need to put these through one of our new virtual cables. I use Line 1.

To do so, go to your list of Recording devices, find one of the microphones you're using and right-click > Properties.

From here, we want the Listen tab. Check the (most likely unchecked) box labelled Listen to this Device and select Line 1 as the device to play the microphone back through.

Repeat the process with the second microphone.

In order to have full control on where the main game and application sound goes, we'll be shoving that all through Line 2. We can't use Listen functions, so we shall instead go to the Playback tab, right-click on Line 2 and set it as our Default Playback (and Communications for safety's sake) Device.

We now have multiple audio sources condensed into two, ready for OBS to use! Fire up your copy and go to the Audio tab in Settings.

In order for the setup to work conveniently for our commentary team, something counter intuitive is going on here. We actually need Line 1 (the microphones) to be picked up by OBS as the main audio while Line 2 (the main audio) is output as the microphone. This is the trick to allow us greater control over which headset hears what microphone. Otherwise both commentators will hear themselves repeating which does even the best public speakers' heads in.

Step 3: Configuring the Headsets

Return to your Virtual Audio Cable start menu. We need to use a program it provides to tell what all our headsets are going to be picking up from our fake cabling.

Make sure you're using MME, not KS for this. Don't forget to run as Admin!

This will bring us a new configuration tool. We need the Wave In option to be Line 2 (our main audio). We need Wave Out to be one of our headsets.

Simply click Start to get it going. I strongly advise firing up the programs providing the audio you want streamed after setting this up. In the event that the audio becomes crackly or stutters, simply restart the program providing said sound. It happens now and then, likely a bug of the particular version I'm using. Feel free to minimise this once you've tested the audio and know it's working.

In order to hear only the other microphone, we need to fire up another instance of this Audio Repeater. This time we want the Wave in to be the name of that microphone while the Wave Out stays the same as above.

Once again hit Start, talk through that other headset while listening to the receiver and check that it's all working. If it is, minimise this one too.

Then simply repeat this process with your other headset. You'll end up with four copies of the Audio Repeater like so.

And there you have it! Run some test recordings of your combined audio + microphones to make sure it's all working then enjoy speaking with each other! If you need to adjust the game volume, use your good ol' Windows Audio Mixer by right-clicking that sound icon.

I hope this all makes sense to you. If not, shoot me a comment and I'll edit this piece accordingly.