Can I change length of file to be converted?

I’m trying to convert a .MKV file using ConvertxtoDVD It works on several but the final episode seems to have a problem in the final seconds of video causing the conversion to freeze on a particular frame.I left the program alone for an hour and nothing. Is it possible to “trim” or change the duration of the file so I can stop conversion before it reaches the “bad spot”? Help Please.