BaroneOSD is a PAL video overlay impression WITHOUT additional hardware required (NO LM1881 Sync generator).

Use only 3 pin:

D1 (USART TX) used to pump pixel in the video connected with a 330Ohm resistor to D6

D6 (AIN0) Video in/out, connect here you camera or radio TX.

D7 (AIN1) 0.3V Voltage reference (you can use a partitor resistor)