Audio control allows user to control audio devices with various buttons.
Audio control has two sides:
Home Assistant automations "tie" these sides together.
Trigger event can come from multiple sources:
Route of event is different depending on source but eventually all events become events in Home Assistant.
There is several Home Assistant automations that are used to adjust audio devices. Automations add abstraction level to adjustments. Behavior of automations can be controlled with variables, such as "start volume", "end volume" and "transition time".
Events have different types of predefined variables. This way each event can be easily configured to produce different type of audio device adjustment.
The actual adjustment of audio device is conducted by Home Assistant through build in integrations.