A method of and apparatus for supporting and enabling the selection and mixing of multiple input data streams from multiple sources within a receiving device allowing external control includes a receiving device, a control device and one or more source devices. The receiving device receives input data streams from the source devices. The input data streams are provided as inputs to selectors within the receiving device. The selectors output selective ones of the input data streams to a mixer, based on control information received from a control device. The mixer then combines the selected input data streams into an output stream, based on control information received from the control device. The interfaces and functions of the selectors and the mixer are provided to the control device in response to a request from the control device. As the control device receives control inputs, the control device provides control information to the selectors and the mixer within the receiving device to control the output of the input data streams.