I have been trying for a couple of days to convert a movie from MKV format to MP4. The movie has forced subtitles, which I have in an SRT file. When I do the conversion and look at the areas with the subtitles, there are 2 squares that appear at the end of each subtitle. I do not see these in the SRT file, so I am not sure what is causing these to appear. Any help in fixing this would be appreciated.