Whether audio is either playing, or will play as soon as processingState is AudioProcessingState.ready. A true value should be broadcast whenever it would be appropriate for UIs to display a pause or stop button.
Since playing and processingState can vary independently, it is possible distinguish a particular audio processing state while audio is playing vs paused. For example, when buffering occurs during a seek, the processingState can be AudioProcessingState.buffering, but alongside that playing can be true to indicate that the seek was performed while playing, or false to indicate that the seek was performed while paused.
final bool playing