[vdr] How to extract HD dvb subtitles (and possibly convert to srt)?

I've a media player that only understand srt subtitles, so I'm looking for a way to extract the dvb subtitles from a vdr ts recording, and then use some kind of ocr to convert it to srt. I asked google and I came empty handed (many people asking the same question with no working answer).

What I tried so far:

- ProjectX (fails because it doesn't like hd pixel coordinates) - avidemux (it has a ts->srt option but it only allows pids up to to 255, and the lucky few that managed to make it work say that it doesn't work with hd) - mencoder -vobsubout (it just produces garbage instead of good pictures, at least according to subrip)

Any other option?

Bye