The UPnP Media Renderer
UPnP Media Renderer's software implementation
RenderingControl
This class is an implementation of the UPnP RenderingControl service and is responsible to manage the volume of the renderer through a direct interaction with ALSA (Advanced Linux Sound Architecture). As seen for the AVTransport class, the methods of this class are invoked by the main class when its actionControlReceived method receives a SOAP request containing an action that belongs to the RenderingControl service. For more details you can look at the source code of the main class of the renderer in the Control section (RenderingControl actions).