DV for Encoded MKV files to X265

[PhantomICEMAN]

Hi i currently have files that are mkv's that have DV layer of 7.6 as an enhanced layer. I am currently trying to encode these to x265 to make them smaller using ffmpeg upon the completion i want to re add the dv meta data back in. I have tried using the RPU injection method however when i try and run the file in plex it says the file cannot be played. As i understand the injection method doesnt work with every player out there. I have tried to convert the enhanced layer back to profile 8 without any encoding and that works flawlessly but i cant get my head round how you can do it with a rencoded video file. I have seen this done on file i have in my library but cant figure out how. Any ideas?