What Is an SRT File?
By Jeremy R. Schwartz
Updated February 10, 2017
Ever watched a foreign movie with subtitles? Chances are, if you downloaded it, then those subtitles were stored in a SRT file. The file format SRT, originally the output of the subtitle extraction program SubRip, is a widely accepted container for caption text and timing information. Commonly packaged with ripped DivX movies, SRT files can be read and created by a variety of programs or found online.
With the advent of movie "ripping" software, home movie enthusiasts needed a way to also extract subtitles. Along came SubRip, an optical character recognition (OCR) program that could (with some training) pull the subtitle text and timing information from a digital movie file and save it to a text file with the extension SRT. As media piracy grew in popularity, so spread the subtitle format SRT along with it. It is now one of several "standard" subtitle types.
SRT files are simply text files listing subtitle information: the number of the current subtitle, the start and end times when the subtitle should appear onscreen, and up to two lines of subtitle text. For example, the 17th and 18th subtitles starting about two and a half minutes into a film: 17 00:02:34,000-->00:02:37,500 He didn't see them [his family] for a year, so he's really excited. 18 00:02:38,000-->00:02:41,500 He's really excited, he really missed them so he's very thrilled. The time format used is hours:minutes:seconds,milliseconds. Milliseconds are precise to three decimal places, and use the French style of commas in place of a period. Since the SRT format is based on time instead of frames, subtitles must be customized to the movie file which varies based on the source.
When accompanying a media file, most media player programs will automatically recognize a subtitle file if they share the same name. If subtitles exist in several languages, it is common practice to append the language to the end of the filename, so that it will be easy to tell English from German with "Movie.eng.srt" and "Movie.ger.srt." In Media Player Classic (from the XP Codec Pack), for example, select between subtitle "tracks" from the menu "Play / Filters / DirectVobSub."
The following are a selection of programs that work with SRT files. Some of them, such as SubRipper, extract subtitles from video to an SRT file. Others, such as VideoLAN VLC, are media players that automatically show subtitles from an SRT file when playing the related video. Use any text editor to view and edit SRT files, or the aptly named "Subtitle Tool" to perform actions like converting framerates or shifting and editing captions. Editing: SubCleaner (Mac), SRT2SUP(Win), CyberLink PowerDirector (Win), Subtitle Editor (Linux) Creating: D-Subtitler (Mac), SubRipper (Win), OGMRip (Linux) Watching: Windows Media Player with VobSub plugin (Win), Media Player Classic (Win), VideoLAN VLC media player (All)
Some media players require strict formatting for SRT files, such as a two line limitation, no overlapping subtitles, or a file size limit. To avoid loading errors, match subtitle file name to media file. Separate subtitle files (SRT) may not work in all DVD players when burned to a disc---some DivX players can play AVI and SRT files.
An North Carolina State alumnus, Jeremy R. Schwartz has published several short articles in scientific journals since 2006, most of which dealt with computational algorithms for physical or environmental modeling. The biggest thing that keeps Schwartz from writing is his career as a professional software and web developer.