Originally Posted by G1Nger
May I ask what TLC you use with ClownBD? Does Clown support 3D BDs? I haven't used it very long and maybe am missing something in the setup. Also, I didn't think it would "shrink" the output size as does BDREBUILDER to fit on a 25GB disc but again I'm not that familiar with the software. Yes to your questions above. My issue lies strictly with a standard Bluray player and burned Movie Only ISO - the separate sub track does not turn on automatically. Thanks for your help.
I'm not sure about 3D support in Clown. It doesn't recompress, though you might be able to use only pieces of it to get what you need.
If you run the Clown gui in batch mode, it generates a *.bat file which you can peruse and edit, and a meta file for tsmuxer. In the no-recompression case, you would need to rename the proper sub file to add _FORCED to the name, like: Subtitles_5_English_FORCED.sup
Then edit the meta file to match. Clown will see that special filename and (in a step following remux and before imgburn) modify the BDMV code to force on that subtitle track.
I'm not sure how BDREBUILDER creates an iso file. If there's an intermediate step just before the iso is created, you could run this Clown step to modify the BDMV code. But if the iso is created all in one step, it might be too late. Somehow you would need to modify the files within the iso. I'm sure that's possible I just don't know how.
More disorganized thoughts on forced subs on my wiki