Hey its working for me.  There are some sites e.g. http://www.mediasoftpro.com/ where they give already built dll which we can easily implement in our project. All such dlls are actually wrapper to the free tool ffmpeg.exe which can convert videos and audios from one format to another. So i thought to use the tool itself instead of the wrapper dll. I have tried very simple example n its working for me so thought to share it it with all.

Download ffmpeg.exe from  (http://ffdshow.faireal.net/mirror/ffmpeg/). you will get a dll along with it (pthreadGC2.dll) keep both the exe and this dll together.

 FFmpeg Documentation (http://ffmpeg.mplayerhq.hu/ffmpeg-doc.html) will be required for the syntax.

If you run it via command prompt then this is the syntax

ffmpeg -i inputfilename outputfilename

If it is to be executed via .net then follow what kalesh had suggested in the post before. Do remember to give write permission to the asp worker process on the folder where the resultant flv file will be saved. If you dont then the program will run without any error or warning but output file will not be produced.

One more thing it do not convert .wmv files to .flv . Is there any way out to it........?