I have some MP4 files with corresponding subtitle SRT files. I want to embed the subtitles in the MP4 files for better viewing experience with my Apple TV. Is there a way to do that without re-encoding the entire files? Right now I re-encode the whole thing with HandBrake but since the H.264 stream is already in the format I want it should be easier to just embed the SRT into that, but I can't find the tools to do it. I tried Submerge, which burns them in and that's not what I want to have.