What is spatial-relay?

Spatial Relay is a small macOS app that lives in the menu bar at the top of the screen, with no icon in the Dock. Its job is to take the audio playing from the Spotify desktop app and route it through a different Apple audio system, one that supports Spatialize Stereo, a feature meant for AirPods models that support Spatial Audio. Normally Spotify sends its sound straight to whatever output device is selected. Spatial Relay instead taps into that audio stream, holds it briefly in memory, and hands it to Apple's own playback system so the Spatial Audio effects can be applied properly. The README stresses that it does not compress, resample, normalize, or change the volume of the audio in any way, it simply passes the same stereo signal through a different playback path, and Spotify's own sound quality settings still apply as normal. To use it, someone connects AirPods that support Spatial Audio, starts playing something in Spotify, opens Spatial Relay from its menu bar icon, and clicks a button to start the relay. macOS will then ask for permission to record system audio, which needs to be approved for the relay to work, and afterward a person can turn on Fixed or Head Tracked spatial audio from the normal macOS sound menu. The audio only stays in a temporary memory buffer, is never written to disk, sent anywhere over a network, or tracked in any way. The app only works on Apple silicon Macs running a recent version of macOS, with Spotify Desktop and Spatial Audio capable AirPods, and building it from source requires Xcode. Prebuilt versions are available on the project's release page but are not notarized by Apple, meaning a normal Gatekeeper trusted build requires compiling it yourself with a personal developer account. The project has one GitHub star, is written in Swift, includes automated tests that run through Apple's own build tooling, and is released under the MIT license. It is not affiliated with Spotify or Apple.