Submerge is an app that allows you to add subtitles to your files. It is not a tool that adds subtitles to your files in real-time, though. It rather uses a process called hard-coding that embeds subtitles on your video files. It actually imprints them on the video, so they will be included with the video file, regardless of the player that you use and its ability or inability to play subtitles along with video files. Thus, it becomes very useful for users who want to watch video with subtitles on devices that have no support for them, like iPods, iPhones, video game consoles, etc.
Using this app is incredibly easy. All you should do is open a video file and then select a supported subtitle file (SRT files are supported). Submerge will render the subtitle file and you can then edit the font type, the size, the alignment, and even add a delay if needed. Changes require that the subtitle file is rendered again, and that takes 15-20 seconds each time. But once you get your settings right, you won't need to render the subtitle file more than once with each file.
After you are done with the subtitle settings, you can export the file to save it. There are a few different devices listed, such as iPods, iPhones, and Xbox 360. The process takes around 40 minutes for a 40-minute file, which isn't incredibly fast.