Signal Input System

A signal input system to input an image signal and a sound signal from source equipment to sink equipment through a High Definition Multimedia Interface, wherein

• the source equipment comprises:
• a first transmission section to transmit a first format signal to the sink equipment through a predetermined first line in the High Definition Multimedia Interface, the first format signal having a voltage value corresponding to a format of the image signal;
• and
• a second transmission section to transmit a second format signal to the sink equipment through a predetermined second line in the High Definition Multimedia Interface, the second format signal having a voltage value corresponding to a format of the sound signal, and
• the sink equipment comprises:
• a first reception section to receive the first format signal transmitted through the first line by the first transmission section;
• a second reception section to receive the second format signal transmitted through the second line by the second transmission section;
• a first judging section to judge the format of the image signal based on the voltage value of the first format signal which is received by the first reception section;
• a second judging section to judge the format of the sound signal based on the voltage value of the second format signal which is received by the second reception section;
• a first setting section to set an image output based on a judgment result of the first judging section;
• and
• a second setting section to set a sound output based on a judgment result of the second judging section, and wherein
• the first line is a line to perform a transmission and a reception of a hot plug signal which indicates that the source equipment and the sink equipment are connected to each other, and
• either one of the first format signal and the second format signal has a function as the hot plug signal.