Thank you for the quick response but I have checked the DCMI configurations and even configurations of the decoder. But not finding any clue where its going wrong.
After adjusting crop settings, now its scrolling down slowly.
Measure waveform directly on VSYNC input pin of mcu (touching physically the pin itself - I am aiming at bad solder joints); read out and check content of respective GPIO pin.
I don't use DCMI so don't know how exactly it detects the syncs, if it's not edge- but level-sensitive, then maybe also VSYNC polarity is incorrectly set.