Android has a long and complicated history with audio output, but Google has been improving audio on Android with higher quality sound and lower latency. In Android O, developers will have a new tool to perform audio transitions and effects.

Apps can, of course, do these audio transitions now, but they're using third-party tools. Android O will bring a class called VolumeShaper that can be configured with a few lines of code to automatically apply your desired transition based on a volume curve, interpolator type, and duration.

By modifying those three variables, developers can make audio do just about anything—fade-in, fade-out, cross fade, ducking, and more. There's also a "replace" method that can be called while AudioShaper is already running, allowing devs to alter the curve from that point. Neat stuff, and coming to your ears soon courtesy of Android O.

Source: Android Developers