Bilingual SubtitlesSource code
DualSub is a tool which allows you to merge two SRT subtitles in a single file. The idea of using merged subtitles (let's call them dual subtitles or bilingual subtitles) is to watch movies/series in original version with two sets of subtitles. This can be used to learn a second language while watching movies/series. This kind of subtitles allows you to learn words, expressions, idioms you do not understand since the translation is automatic and instantaneous (typically to your mother tongue from the second language you are trying to learn).
If you want to create your own dual subtitles, you need the video to be played with its subtitles. Ideally, you should have two subtitles SRT files for a single video (for instance, the first SRT subtitle in English and the second one in other language). There are plenty of web sites available to collect SRT files, for example opensubtitles, subscene, and so on.
DualSub also allows you to translate SRT subtitles. Sometimes, it is difficult to find the subtitles for a given content in two different languages. For that reason, DualSub is able to translate subtitles. To that aim, DualSub uses the Google Translate online service. You will be requested to fill up a captcha in order to ensure that there is are a human behind the request to Google Translate.
Here you can see an example of a video with dual subtitles. It is a piece of Kill Bill Volume 1 with English an Spanish subtitles. Be careful if you have not seen this movie since it is the end of the movie and contains important spoilers!!!