I've been playing around with programs that rip the celltimes. There seems to be no accurate software for doing this and I'm not sure I understand why.

I tried ChapterXtractor, DVDDecrypter, PGCDemux and IFOEdit.

IFOEdit and PGCDemux produce the same results. ChapterXtractor will generate matching results if you force it to display all cells and set it to 30fps (instead of the 29.97 default), but it may skip the last celltime. (This is when ripping from an NTSC disc not PAL).

The movie I was testing this with was only a frame or so off for chapters using the PGCDemux cells, which were much closer than the DVDDecrypter list which was just plain wrong.

I dunno what the situation is with DVDDecrypter, I'll play a bit more, BUT I'm going to update the guide in the next few days removing DVDDecrypter as the ripper of choice.

Edit: Or not. It would seem the error creeps in ONLY in NTSC celltimes.

On PAL DVDs, DVDDecrypter and PGCDemux produce the same results (with PGCDemux on the default settings).

The guide is fine as it is, but I recommend using PGCDemux if you're working with NTSC celltimes.