Subtitles are very important to the community. We all use them regardless of whether we have a hearing impairment or not. I have found a great tool that allows me to accurately  and efficiently subtitle videos – Subtitle Edit.  I am able to add subtitles even with the low amount of vision that I have using this tool. It is open source and it is only a recommendation. Like anything, it is only as good as the information that is added to it. follow the link to learn how to use Subtitle Edit