The ITU-RBT.656-4 standard defines the functional timing for an 8-bit wide interface.
There are two timing reference signals, one at the beginning of each video data block SAV (0xFF000080) and one at the end of each video data block EAV (0xFF00009D). Only data sent between EAV and SAV is captured. Horizontal blanking and vertical blanking are ignored. Use of the SAV and EAV synchronization eliminates the ISI_VSYNC and ISI_HSYNC signals from the interface, thereby reducing the pin count. In order to retrieve both frame and line synchronization properly, at least one line of vertical blanking is mandatory.
The data timing using EAV/SAV sequence synchronization are shown in the following figure.
Figure 1. SAV and EAV Sequence Synchronization
