Here is another solution that TI has chosen to avoid. It is using common mode modulation to transmit the backchannel. In this example, backchannel data is transmitted continuously. The common mode signal of the video data is being modulated by the backchannel and this creates common mode modulation (shown in orange). Common mode modulation translates directly into increased emissions.  Although one can get continuous backchannel, the limitation here is EMI mitigation and this can be very costly because of the additional board components needed and the scheduling of a production release.