Mac sound capture, take 2

Awhile ago I wrote up some notes on recording League of Legends videos using OBS. I still mostly follow that horribly manual workflow, but I was having a hard time getting sound to work reliably. I think I have it sorted out now.

  1. Install Matt Ingalls’ SoundFlower 2.0b2 from GitHub
  2. Reboot. Not clear this is necessary, but I think it may be.
  3. Follow these instructions for configuring audio. However, Soundflowerbed is no longer included. Fortunately you can ignore that if you Audio MIDI Setup yourself (standard Mac software)

The key thing here is you use Audio MIDI Setup to create a new “Multi-Output Device”. That’s a virtual sound device that can send output to more than one place, in this case both “Built-in Output” (your speakers) and “Soundflower (2ch)” (the capture device).

Then you use the Sound preference panel to tell the Mac to play output to that new Multi-Output Device. Now every sound your Mac plays will both come out the speakers and be sent to SoundFlower.

Then you set up OBS to accept audio input from the SoundFlower device.

Unfortunately setting the default sound output to Multi-Output Device will break the volume control from the Mac keyboard. You can still set the volume for each output in the Sound panel though, just be sure to leave Multi-Output Device selected when you’re done. You want to modulate actual volume using Internal Speakers’ control. Set the Soundflower and Multi-Output Device volume to maximum, so that sound is passed through at full volume to OBS.

In previous versions of this setup I found cases where OBS could record audio correctly, but only if it was launched after the program playing the sound. No idea what that was about. I don’t think that’s happening any more.

If you’re serious about doing more fancy audio routing, the commercial Loopback program is pretty good. At $75 though it’s a bit pricy for what I’m doing.