I assume you're asking for a program that converts the filetype rather than for actual editing seeing as your question didn't mention editing at all other the it being a characteristic of the specific application that you think you need. Well, it depends on what filetype you want to make it, once you know that, go to google and use the search string 'current-filetype to preferred-filetype converter'
EX: If I had an .avi file that I wanted to convert to an mpeg...
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