Background Music
Automatically pause your music, set individual apps' volumes, etc.
Automatically pause/unpause your music player when other audio sources are playing/stopped. Per-application volume control. Record system audio. No restart is required to install. Background Music automatically pauses your music player when a second audio source is playing and unpauses the player when the second source has stopped. Background Music provides a volume slider for each application running your system. You can boost quiet applications above their maximum volume. You can record system audio with Background Music. With Background Music running, launch QuickTime Player and select File > New Audio Recording (or New Screen Recording, New Movie Recording). ...