Files that contain the .sub file extension are usually files that store information about movie subtitles. These files contain data about the movie subtitles, such as the subtitle text, the point at which each subtitle should be displayed and information about the corresponding video file.
SUB files are most often assigned by the CaSat Suite subtitle software and the files that are saved with the .sub extension are usually used for the subtitles in DivX formatted movies.
It is important to note that the SUB file does not contain any actual video data. Just the references for the subtitle information.
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