Abstract: A multiplexer includes a first interface configured to receive one or more HDMI or DVI signals for transmission over a respective one of an HDMI or DVI interface; a second interface configured to receive external data from a data source, the external data being intended for transmission over the HDMI or DVI interface; a data multiplexing device having inputs coupled to the first and second interfaces, and having an output, and being configured to multiplex the external data with information on one or more signal paths of the HDMI or DVI interface; and a transmitter coupled to the output of the data multiplexing device, configured to transmit the external data across the HDMI or DVI interface.