Externalsubtitles: To add subtitles to a file that does not contain it's own subtitles you can use SRT files. A good place to find a wide variety of (free) SRT files is OpenSubtitles.org
Step 2: Select the subtitle language/file you wish to use. For some languages you may also need to adjust the encoding type so special characters are displayed correctly. Through this menu you can also adjust options such as subtitle appearance, position, and offset.
You can easily change synchronization of your subtitles with any modern video player today. However, if you want to permanently setup synchronization you need to do it manually (hard way) or by using some specialized software.
There are many subtitle editors on Windows or Linux but they do more than synchronize, and therefore are rather complicated for the simple purpose of fitting a subtitle to a movie. Many video players can delay/change the time of the subtitle in order to synchronize it but not many are able to save that change.
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