Spur: Audio Output per App

macOS knows exactly one audio output. If music plays on an AirPlay speaker, everything else goes there too, and the video you watch alongside it arrives almost two seconds late out of the same speaker.

Spur separates the two. One app's sound goes to a second output device while everything else stays where it is.

IN SYNC WITH THE PICTURE An AirPlay speaker reports a delay of about two seconds, and players line the picture up with it. Tap the sound off and play it somewhere else immediately, and it runs ahead of the picture by exactly that much. Spur works out the difference between the two devices and compensates for it. If you would rather trust your ears, move it by hand.

VOLUMES THAT STAY PUT Percentages are not comparable between two devices. The same number can be seventeen decibels louder on a speaker than on the built-in ones. Spur remembers the level you last chose for each device and restores it when you switch. No more sudden loudness.

IN THE MENU BAR No window, no Dock icon, no setup assistant. Click the icon in the menu bar, pick the app and the target, flip the switch.

WHAT SPUR DOES NOT DO Record anything, collect anything, talk to any server. It does not even have the entitlement for it.

Discovery signals