The approach of not erroring on fchdir is consistent with old libdvd 4.1.3 but nevertheless I've added a statement to print out what goes wrong. This will help further root cause analysis.
The way to test is with DVD files stored as VIDEO_TS folder and files on your file system (not ISO, not optical).
Fix inability of libdvd 4.2.0 to read DVDs stored as VIDEO_TS files o…
…n non-Windows OSs.