A method comprising: establishing a connection between a source device and a sink device , the connection comprising at least a first physical channel configured to transmit uncompressed video data unidirectionally from the source device to the sink device, and a second physical channel separate from the first physical channel; receiving, at the sink device, a discovery signal from the source device over the second physical channel to confirm support of a bidirectional communication mode by the source device over the second physical channel; establishing, at the sink device, bidirectional communication with the source device responsive to receiving the discovery signal; responsive to establishing bidirectional communication with the source device: communicating, over the second physical channel, a signal comprising: a common mode signal comprising control data transmitted as a plurality of packets bidirectionally between the source device and the sink device, wherein the common mode signal is transmitted at a first speed, each of the one or more packets comprising a payload containing a predetermined number of bits of control data; and an audio signal comprising audio data transmitted from the sink device to the source device, the audio signal overlaid on the common mode signal and transmitted at a second speed higher than the first speed. establishing a connection between a source device and a sink device , the connection comprising at least a first physical channel configured to transmit uncompressed video data unidirectionally from the source device to the sink device, and a second physical channel separate from the first physical channel; receiving, at the sink device, a discovery signal from the source device over the second physical channel to confirm support of a bidirectional communication mode by the source device over the second physical channel; establishing, at the sink device, bidirectional communication with the source device responsive to receiving the discovery signal; responsive to establishing bidirectional communication with the source device: communicating, over the second physical channel, a signal comprising: a common mode signal comprising control data transmitted as a plurality of packets bidirectionally between the source device and the sink device, wherein the common mode signal is transmitted at a first speed, each of the one or more packets comprising a payload containing a predetermined number of bits of control data; and an audio signal comprising audio data transmitted from the sink device to the source device, the audio signal overlaid on the common mode signal and transmitted at a second speed higher than the first speed. a common mode signal comprising control data transmitted as a plurality of packets bidirectionally between the source device and the sink device, wherein the common mode signal is transmitted at a first speed, each of the one or more packets comprising a payload containing a predetermined number of bits of control data; and an audio signal comprising audio data transmitted from the sink device to the source device, the audio signal overlaid on the common mode signal and transmitted at a second speed higher than the first speed. <EOS>