What is sound_pref?

SoundPref is a free, open-source macOS application that gives you detailed control over how your Mac handles audio. It lives in your menu bar and lets you adjust the volume of individual apps, mute specific apps without affecting others, and send each app's sound to a different output device. For example, you could route music to your speakers while keeping a video call's audio in your headphones. It is described as a free alternative to a paid app called SoundSource. The app requires macOS 14.4 (Sonoma) or later and runs on both Apple Silicon and Intel Macs. It is written in Swift 6 and released under the GPL-3.0 license. The project is labeled as an MVP (minimum viable product), meaning it covers core functionality but is still in an early stage. Beyond per-app volume and routing, it lets you quickly switch system audio devices from the menu bar, pin favorite apps so they always appear in the panel, and save your settings so they persist across restarts. SoundPref works by using a Core Audio API introduced in macOS 14.4 that lets one app capture and control audio from other apps without needing a kernel extension. When you change an app's volume or output, SoundPref taps into that app's audio stream, applies a gain adjustment for volume, sends the audio to your chosen device, and mutes the original default device to prevent the sound from playing twice. Building the app from source requires Xcode 15 or later. The README notes that running it directly with Swift commands often fails due to macOS sandbox permissions, so the project includes a build script that compiles, signs, and launches the app. There is also a separate script for creating a disk image for distribution. On privacy, the README states that all audio processing happens locally, with no recording, telemetry, analytics, or network calls. A purple dot appears in the menu bar, which is Apple's standard indicator that an app is accessing system audio.