I got it figured out after reviewing more info and more videos in YouTube. No one video or web article covers everything that was required to make this work. I think I'll make my own video, specifically on recording Studio One. The configuration I figured out for Studio One should work for other apps that OBS and iShowU don't capture for you in their native installation. To clarify, these instructions have only been used and tested in making a recording video with audio. Streaming should work just the same with these settings but I have not tested that.
This is definitely not straight forward when you see how it's done. In fact, some of it is counter-intuitive. e.g. Making iShowU Audio Capture the default input device (see the Microphone icon next to it) in the Mac's Audio MIDI Setup, Audio Devices screen. When iShowU Audio Capture is installed it should set be set as the default input device for you. If not, right-click on iShowU Audio Capture and select: Use this device for sound input. Without that set, iShowU will NOT capture your screen audio!!
I know it seems illogical, but it behaves as internal 'mic' on the system bus to grab all audio coming down the pike. The narration is added later in OBS. This is farther down the chain, so it is added on to the audio pipeline.
Open the Audio MIDI Setup app. I suggest you add it to your Dock, at least until you have this configured and working. Click on the + box down in the lower left corner of the window. Select Create Multi-Output Device.
Under the Use column, select the output devices you want to use. At a minimum, that should include: iShowU Audio Capture, and, whatever device your headphones are using. I like to select Drift Correction for every device but the Master Device. The Master Device must be: iShowU Audio Capture.
See a problem in this configuration? The audio (both narration and screen output) will come out of the Mac's internal speakers as well as into my headphones. My headphones are connected through an Audiobox 96 USB audio interface, so I've selected it in the Use column. I don't want the sound coming out of the internal speakers as well, so I uncheck Built-in Output in the Use column. Otherwise, the internal microphone could pick up the sound and create feedback or an annoying echo for the person watching my video.
Every video I watched said to go into the Mac's System Preferences Sound and set it to: Multi-Output Device. I found this to be an unnecessary step. As soon as you right click on the Multi-Output Device and select: Use this device for sound output, it is automatically changed in System Preferences Sound. They're simply 2 different places to control the same setting.
The one thing that can ONLY be set in the Mac's Audio MIDI Setup is: Play alerts and sound effects through this device. For that, you must select an output device and right-click on it to select this setting. In my example screenshot above, I set it to the Multi-Output Device, as denoted by the Alerts icon next to the Speaker icon. The Alerts icon is a miniature Mac Finder icon. At the moment, it eludes me how to mute or suppress the alerts and sound effects from being heard in your video.
To add narration to your video, you set the input device in OBS to either your Mac's internal microphone or an external microphone.
Open the OBS app and click on Settings.
1. Select Audio on the left.
2. On the right, open the list next to Mic/Auxillary Audio Device and select: Built-in Microphone
3. Open the list next to Mic/Auxillary Audio Device 2 and select: iShowU Audio Capture
4. Click Ok to save your settings and close the Settings window.
While most videos say your microphone should be the first Mic/Auxillary Audio Device and your headphones or internal speakers should be Mic/Auxillary Audio Device 2, I've found it makes little difference which channel they're in. Those settings control which audio track in the main OBS window is Mic vs Headphones/Speakers.
Creating the Multi-Output device is the glue that ties all the output together. The last step is configuring Studio One so that its output is also captured and included in your video.
In Studio One, the Audio Setup Playback and Recording devices MUST be set to "Multi-Output Device"!!!
I've covered the major steps here. I've skipped some of the stuff that's in every other video out there, like where to get iShowU and how to install it.
I will demonstrate all the above steps in a future video on YouTube, including how to use a side chain in OBS to lower the volume of the background audio whenever the narrator speaks.
I spent all week trying all different configurations and watching countless videos and reading numerous web pages. Out of desperation, I tried, "Audio Hijack" and "Loopback" by Rogue Amoeba. Their trial periods expired before I ever got them to work, but as it turns out, they are not needed.
ENJOY!
