In the ADV7842-ADV7511 evaluation board, without connecting any video source I loaded the composite video script with 0xDD in SDP map set to 0xB0 to disable free run. 0x56 in SDP map showed part was not free running. But another board interfaced with the evaluation board's ADV7842 is still receiving 480 blank lines a frame. Checking the ADV7842 data lines on the evaluation board using scope showed that data is passing through. Why does the decoder send any data?