[ADV7511W] Unused input pins.


I have a question about unused input pins of ADV7511W.

The ADV7511W_Hardware_Users_Guide.pdf says as follows:
     6.1.1 Unused Inputs
     Any input data signals which are not used should be connected to ground.

Is it OK that the unused input pins are connected to ground directly?
Should we use pull-down resistance to be connected to ground?
If we should use pull-down resistance, how much ohm of resistance should we use?
1kohm, 4.7kohm or 10kohm? etc.

Thank you!
Best regards.