pls. help me it's urgent, drop video frames during start/stop button click

[C# Programming]

Hi,

Can anybody please help me to resolve below described issue?

using DirectShow i build application which show live preview and also capture video frames.
there is start/stop button available on user interface which are used for starting and stoping video frames capturing.

But when a user click on start/stop button, my preview window become totally black coloured for some time and i lost video frames during that period.

Please help me it's urgent.

Thanks & Regards,
Kunal.