thanks for your reply
THE Led We are using is sony 46nx720 and Heran 46z57
our crew make some test
( if connect to Normal LCD like PC monitor HDMI ) there is no delay ( may be less
BUt Even if we connect short cable from cam to LED ,… there is a delay
For the How much delay still need to test it out ( but u can see it with your naked eye there is a delay
( do this mean that LED is not suitable for live )or switcher also
Tim