Transition Minimized Differential Signaling (TMDS) on HDMI carries video, audio, and auxiliary data via one of three modes called the video data period, the data island period, and the control period. During the video data period, the pixels of an active video line are transmitted. During the data island period (which occurs during the horizontal and vertical blanking intervals), audio and auxiliary data are transmitted within a series of packets.
The control period occurs between video and data island periods.