I need help in creating black & white grains effect(u
know sometimes, if a channel does'nt work or does'nt get the signal
properly. The screen will be filled with black & white dots
randomly) as in TV.
The flash.display.BitmapData class is what you need to use.
It has a method called noise which does exactly what you ask for.
Note that it is very CPU intensive. A better solution might be to
take a sequence of them on Fireworks or Photoshop, and then import.
Here's some sample code to try out (just paste on Frame 1 of
a blank document):