setaudio

A simple launchd plist to set a usb audio device output, automatically, when the device is attached. This plist makes use of whosawhatsis's handy utility audiodevice. This can solve the problem of a Mac laptop staying on internal speaker output, even when docked.

Customization

By default, this is set up for detecting an Elgato Thunderbolt 3 dock (which includes a USB-based audio input and output). If you're using a different USB audio device, you will want to edit the .plist to match your device.

1. Change the last ProgramArguments string (specifically, the last argument of the audiodevice program) to match the exact name of the audio output you want to use. In my case it's Elgato Dock (note that this is the name given to the device by the Elgato Dock utility; if you own this dock but haven't installed the utility, the name is USB Audio CODEC). Also remember to escape spaces with a backslash (as in Elgato\ Dock)

2. Change the idProduct and idVendor integers to match the device. This can be found in the System Information app, under USB (or, ioreg -p IOUSB in Terminal).

3. Change the IOProviderClass string to match the device. This can also be found by running ioreg -p IOUSB in Terminal. For the Elgato dock it's AppleUSBDevice but yours may be different.

Once you're certain you have the right values in the plist, you're ready to install.

Installation

1. Move the com.eoban.setaudio.plist file to ~/Library/LaunchAgents/

2. Run launchctl load ~/Library/LaunchAgents/com.eoban.setaudio.plist

3. Move the Audiodevice directory to /Applications/

Notes

• The program should now run automatically in the background when your audio device is plugged in.

• To disable, run launchctl unload ~/Library/LaunchAgents/com.eoban.setaudio.plist

• This has been tested on macOS High Sierra and the Elgato Thunderbolt 3 dock only. Functionality on other versions is unknown.