ff-mpeg is mostly used to merge a two video or video with audio file loss without video quality.also you can convert video file in any format to any format.
follow simple five steps to enable ff-mpeg in your localhost.
1. Download compiled dells from here: http://sergey89.ru/files/ffmpeg-php-win32-all.zip
2. Extract zip file and Copy php_ffmpeg.dll from the php5 folder to the C:\wamp\bin\php\php5.2.9-2\ext
3. Copy files from common to the windows/system32 folder
4. Add extension=php_ffmpeg.dll to php.ini file
5. Restarted all services (Apache, PHP...)