Abstract: Circuitry for providing an output video signal from a portable device to an external display, the circuitry including a processor block with an image processor, and a video encoder block with a video encoder for providing the output video signal to the external display, the processor block and the video encoder block being connected to each other by a serial interface arranged to provide image date from the processor block to the video encoder, the serial interface having at least one data lane and at least one first clock lane, wherein the video encoder block includes a first input connected to the at least one data lane for receiving image data and a second input connected to the at least one first clock lane for receiving a first clock signal, and wherein at least one of the video encoder block and the processor block has a third input arranged to receive a control signal for controlling data flow over the serial interface.