Andrew, just an update only.

I want to continue with the Bluray patches despite the problem with 0006-EXPERIMENTAL-add-variable-chapter-interval-to-bdwrit.patch which I had to back out. So I went forward with 0007-0017 which correctly patched but neither the choice of bluray_lpcm.m2ts or bluray_truehd.m2ts worked (got unknown bluray stream pcm_bluray and got unknown bluray audio format 0 ch). You may very well have fixed these in later patches but I am trying to go in order. Then as I patch 0018 and 0019, hunks fail because there is no "every_n_sec" from 0006-EXPERIMENTAL-add-variable-chapter-interval-to-bdwrit.patch was backed out.

No need to reply -- I will continue to work around this and make changes manually so I can see if I can get the tsmuxer muxing and selectable audio codec working because they would be good additions.

from a previous disc write (it is a Rewritable Disc because I have to test over and over and over again when it comes to bluray).

I did look at all other patches that affect bdwrite.C in megapile_8 but see none that could possibly fix the chapter interval.
These are 0016, 0018, 0019, 0020, 0037, 0046, 0052, and 0056. Should I ignore all EXPERIMENTAL patches for bluray?

well, other patches still add tsmuxer muxing and selectable audio codec - but if you have trouble playing disks created even with full patch set - set it aside...