How to set chroma key effect using MLT framework ?

This is one of the big issue that every MLT developer faced while trying to set chroma effect to a video clip. I had a research on this issue and finally got its solution.....the solution is some how like this..........you first declare your video clip and then use the following expression...

"melt avformat:clip1.avi in=0 out=1000 -filter chroma key=#00FF00 variance=0.385"

in the above code "key" is nothing but the colors declared in a hexadecimal format .You can set multiple keys to the filter itself. "variance" is used to set opacity level .you can also vary it as per your preferences.

for any query on MLT framework you can contact me ..my email id is.."animeshnanda@gmail.com"