Originally Posted by dbone1026
How are you creating 1080p IDX/SUB subtitles? Typical DVDs are only 480p IDX/SUB subtitles, and Blu-rays use 1080p PGS/SUP, so the only way DVDFab would be creating 1080p IDX/SUB subtitles would be if you are asking it to create this specifically (I have not used DVDFab in a while, but I don't know why it would insist on creating 1080p IDX/SUB subtitles)
It's just the (very limited) way DVDFab supports MKV subtitles. I usually remux the main movie of my BDs to MKV and here the only two options DVDFab offers is to render one subtitle directly into the video or create external VOBSUB subtitles at 1920x1080 which the Dunes don't support. Also if you look at those "MKVs out in the field"
they almost always have full HD VOBSUB subtitles. As for specifically creating 1080p IDX/SUB you can use BDSup2Sub to go from IDX/SUB to PGS and vice versa.
But it really is a shortcoming of DVDFab, PGS subs in MKV are supported by the official mkvtoolnix for at least 2 years now. But the DVDFab people just don't seem to care although it's frequently requested in the forums.