VobsubMuxer can mux more than one video subtitle languages into one single vobsub file (idx/sub). VobsubMuxer is a portable application that runs on Windows XP , Vista, 7, 8 and Linux. The Vobsub files can be extracted from a DVD and can contain up to 32 subtitle language streams. So if you rip a DVD on your computer, the extracted idx/sub package may contain more than one languages in one file [IDX/SUB]. This is a really good solution if you want to watch your film (test.avi) with all the supported languages that where on that specific dvd ( using the test.idx and test.sub files).
Download and use it now: VobsubMuxer