* If there are not DivX or XviD codec installed in your computer, you need to download and install the DivX or XviD codec (or a player software which supports them) so that you can play and convert FROM DviX or XviD video files.
K-Lite Codec Pack (http://www.free-codecs.com/download/K_Lite_Codec_Pack.htm)
Storm Codec (http://www.free-codecs.com/download/Storm_Codec.htm)
DviX: http://www.divx.com/divx/ (free version is enough for playing and converting DivX video files)
XviD: http://www.xvidmovies.com/codec/
If there are not MP4 codec installed in your computer, you need to download and install a player software which supports MP4 so that you can play and convert FROM MP4 files.
K-Lite Codec Pack (http://www.free-codecs.com/download/K_Lite_Codec_Pack.htm)
Storm Codec (http://www.free-codecs.com/download/Storm_Codec.htm)
QuickTime Player (http://www.apple.com/quicktime/)