How to record emulator gameplay on a mac? (soundflower or alternative)
Solution 1:
Have you tried OBS Studio? Is available for Windows, macOS and Linux and is Open Source.
You just need to configure the size of the canvas from the options and then add the window of the emulator to OBS Studio as a Game Source (if that doesn't work, use Window Capture).
After that, you can mute the Microphone or Auxiliary Input from the Audio Mixer panel, as seen in the following picture:
(I don't have access to a macOS machine right now, but the features are exactly the same between platforms)