Java Programming

HI, i want java code which can convert any video format into .flv format, i did searched on google but did't get satisfied result, i read something about "ffmpeg" but did't get any help from that, please anybody tell me what API's and java code do i need to convert any video format into FLV format , iam using flash player in my website, one more thing i want to generate thumbnail from my video file,how can i do this,i found code for this in PHP but iam unable to find code to generate thumbnails from video in java, I desperately need help ...............