kyleneideck/backgroundmusic

Background Music is a free macOS audio utility that gives you per-application volume control and automatic music pausing, features that macOS doesn't provide natively. The main feature most people use it for is auto-pause: when you're listening to music and a video or notification sound starts playing, Background Music automatically pauses your music player. When that other audio stops, your music resumes. This means you don't have to manually pause Spotify every time a YouTube video starts. It supports iTunes, Spotify, VLC, VOX, and several other players. The second major feature is per-application volume control. macOS normally has a single master volume. Background Music adds individual volume sliders for each running app, so you can turn down a loud game without affecting your music, or boost a quiet app beyond its normal maximum. Third, it enables system audio recording. By selecting Background Music as the input device in QuickTime Player, you can record all the audio coming from your Mac, useful for screen recordings or capturing audio from any application. You would use this as a Mac power user who wants more fine-grained audio control without buying third-party software. It requires macOS 10.13 or higher, installs without restarting, and can be installed via Homebrew. It's written in C++ and Objective-C and is currently in alpha.