An information processing method for use in a receiver , an HDMI receiving unit of the receiver unidirectionally receiving, from a transmitter using a first differential signal, pixel data of an uncompressed image of one screen during an effective video period representing a period from one vertical synchronization signal to the next vertical synchronization signal excluding horizontal blanking intervals and a vertical blanking interval, the method comprising the steps of: receiving by Report Physical Address of CEC control protocol, from the transmitter, a notification indicating that the physical address of the transmitter designates a CEC-compliant device having a specified logical address, said specified logical address being indicative of a device type of the transmitter; characterized in that the method further comprises: transmitting by a LAN sending circuit of said receiver , to the transmitter, a second differential signal representing transmission data different from the pixel data via differential transmission lines formed from a pair consisting of the reserved line and the hot plug detect (HPD) line of an HDMI cable; receiving, by a LAN signal receiving unit of the receiver , connected to the LAN sending circuit , an added signal comprising said second differential signal added to a third differential signal transmitted from the transmitter via the reserved line and the HPD line of the HDMI cable; and subtracting, by a subtracting circuit of the receiver, said transmission data represented by the second differential signal from the signal received by the LAN signal receiving unit . receiving by Report Physical Address of CEC control protocol, from the transmitter, a notification indicating that the physical address of the transmitter designates a CEC-compliant device having a specified logical address, said specified logical address being indicative of a device type of the transmitter; characterized in that the method further comprises: transmitting by a LAN sending circuit of said receiver , to the transmitter, a second differential signal representing transmission data different from the pixel data via differential transmission lines formed from a pair consisting of the reserved line and the hot plug detect (HPD) line of an HDMI cable; receiving, by a LAN signal receiving unit of the receiver , connected to the LAN sending circuit , an added signal comprising said second differential signal added to a third differential signal transmitted from the transmitter via the reserved line and the HPD line of the HDMI cable; and subtracting, by a subtracting circuit of the receiver, said transmission data represented by the second differential signal from the signal received by the LAN signal receiving unit . transmitting by a LAN sending circuit of said receiver , to the transmitter, a second differential signal representing transmission data different from the pixel data via differential transmission lines formed from a pair consisting of the reserved line and the hot plug detect (HPD) line of an HDMI cable; receiving, by a LAN signal receiving unit of the receiver , connected to the LAN sending circuit , an added signal comprising said second differential signal added to a third differential signal transmitted from the transmitter via the reserved line and the HPD line of the HDMI cable; and subtracting, by a subtracting circuit of the receiver, said transmission data represented by the second differential signal from the signal received by the LAN signal receiving unit . <EOS>