on the fly wmv to mp4 converter on the server

I wish to know if it is possible to convert WMV files to MP4 format on the server?

I have security videos which are FTP'd to my server but these can not be viewed on some mobile devices, so wish to find a way to convert to MP4 so that other devices can view them.

once I was using Mp4 Converter (http://mp4-converter.info) for this task. But lost my license code and uninstalled the program lately.