Programs enabling conversion of the file:
If your objective is to convert the file from XVID to the file H264, you can use any of the applications listed. XVID to H264 conversion process in every program intended for this purpose (so-called converters) is very intuitive and everyone is able to manage converting a file.
However, bear in mind that the list may also include programs to support and work with the indicated extensions XVID and H264 - and not only converters. In such a case, you need to open the source file XVID and from the options available in the program, choose ”Save as... H264" or "Export to H264".