Today professional subtitlers usually work with specialized computer software and hardware where the video is digitally stored on a hard disk, making each individual frame instantly accessible. Besides creating the subtitles, the subtitler usually also tells the computer software the exact positions where each subtitle should appear and disappear. For cinema film, this task is traditionally done by separate technicians. The end result is a subtitle file containing the actual subtitles as well as position markers indicating where each subtitle should appear and disappear. These markers are usually based on timecode if it is a work for electronic media (e.g. TV, video, DVD), or on film length (measured in feet and frames) if the subtitles are to be used for traditional cinema film.
The finished subtitle file is used to add the subtitles to the picture, either directly into the picture (open subtitles); embedded in the vertical interval and later superimposed on the picture by the end user with the help of an external decoder or a decoder built into the TV (closed subtitles on TV or video); or converted to tiff or bmp graphics that are later superimposed on the picture by the end user (closed subtitles on DVD).
Subtitles can also be created by individuals using freely-available subtitle-creation software like Subtitle Workshop and then hardcode them onto a video file with programs such as VirtualDub in combination with VSFilter which could also be used to show subtitles as softsubs in many software video players.
Video: Embed Subtitles Into Videos