Hi Chris,
You can add reference to vertical offset since this can be used to adjust the display area of both top and bottom position to have only a few rows in top and bottom that are not used.
Refer 6.1 section for details
/********************************/
V_ADJ[11:0], OSD Map, Address 0x04[3:0]; Address 0x05[7:0]
Vertical offset adjustment for OSD position.
/************************************************.