The evaluation board for the ADV7403 has two scripts for handling SD RGB:
* :625I SCART RGB IN In Thru CP YPrPb 2X1 10 Bit 422 Out through (Encoder in 625i Mode):
* :525I SCART RGB IN In Thru CP YPrPb 2X1 10 Bit 422 Out through (Encoder in 525i Mode)
If you are needing SD RGB capability, I would suggest starting with one of these evaluation boards.
-Matt