easyjasub
Tool to add furigana and in-line translation to Japanese subtitles
...wkhtmltoimage is required, take it from http://sf.net/p/wkhtmltopdf
BDSup2Sub may be useful (BDN/XML subtitles are created as intermediate output).
Basic usage:
easyjasub.exe -ja subtitle.jp.srt -tr subtitle.en.srt
java -jar easyjasub-cmd.jar -ja subtitle.jp.srt -tr