Apparently ffmpeg does not support Blu-ray chapters directly.
MKVToolNix, however, supports reading chapters from the playlist file. If you want to do a full remux (using only
mkvmerge from MKVToolNix), you can use the following command:
mkvmerge /path/to/BDMV/PLAYLIST/00000.mpls -o /path/to/remux.mkv
The created Matroska file includes chapter metadata.
If you only need the chapters you can create a “dummy” Matroska file that only contains the chapters:
mkvmerge -A -D -S /path/to/BDMV/PLAYLIST/00000.mpls -o /path/to/chapters.mkv
-S switches tell
mkvmerge not to copy the audio, video and subtitle tracks.
You can then use the created file with ffmpeg or extract the chapters as XML with
mkvextract (also from MKVToolNix):
mkvextract /path/to/chapters.mkv chapters /path/to/chapters.xml