Video transmission system

A video transmission system for transmitting video data from an encoder to a decoder via a first communication line, the video transmission system comprising:

• a control unit that is connected to the decoder, and that issues a communication establishment request to the decoder in response to receiving a specific signal detection notification,
• wherein the encoder includes:
• a first transmission part that transmits a specific signal for communication establishment to the decoder via the first communication line during a blanking period of the video data;
• and
• a determination part that determines communication establishment of back channel communication in a case of receiving a command signal indicating communication establishment from the decoder via a second communication line after transmission of the specific signal,
• wherein the decoder includes:
• a judgment part that judges whether or not a signal received from the encoder during the blanking period is the specific signal;
• a notification part that supplies the specific signal detection notification to the control unit in a case of the received signal being the specific signal;
• and
• a second transmission part that transmits the command signal to the encoder via the second communication line according to the communication establishment request,
• wherein the encoder and the decoder execute the back channel communication via the second communication line after determination of the communication establishment of the back channel communication.