finally managed to do the "behind the TV"-work yesterday - pictures will follow soon .
Got everything working in general from the scratch, which is the good news, but even after playing around with the settings and searching the forum for half of the night i am still unhappy with a real mentionable delay of the LED's (around 500 msec, maybe even more).
As I have seen videos here in the forum, where the LEDs react almost synchronous to the TV-pictures, has anybody suggestions how to solve this?
My Setup: Pi 3b+, Hyperbian, APA102 LEDs, WisFox HDMI Grabber
Thx in advance