Here's an easy to use multimedia media converter, which I have been using for many years and am happy with its performance. You might want to try it too!FormatFactory is a freeware multimedia converter. You can convert:
Video: MP4, WebM, AVI, WMV, MPG, VOB, MOV, FLV and SWF and others
Audio: MP3, WAV, WMA and others
Image/Picture: JPG, PNG, TIFF, BMP, GIF, TIF and others
Document: PDF, Mobi, Epub and others
Also, you can also join video and audio files
You can download from: http://www.pcfreetime.com/formatfactory/index.php?language=en
Please share your comments if you have used it earlier or after using it.