[neeto33]

To be able to use DSplayer with DVD folder (ifo) you need to config dvd navigator as source AND splitter. But then it's not working 100% some dvd won't play so convert iso to mkv seem to be best option.

Yep got dvdnavigator as both source AND splitter.
Any clue on why some work and some don't? anything to do with them being on smb mount on NAS?

It just don't work with some DVD structure even with using other directshow based player (MPC-HC etc.). Since DVD Navigator filter is not in development anymore and no replacement filter for it, that's the end of dvd ifo playback.

Ok here's the answer - it will & does work fine for DVD structures on the local host with the following configs

<rule filetypes="ifo">
<source filter="dvdnavigator" />
<splitter filter="dvdnavigator" />
<video filter="lavvideo" />
<audio filter="lavaudio" />
</rule>

But there is catch - it must be a local structure. If it is on my NAS I get the following:

When I have "ERROR: CFGLoader::InsertSourceFilter Failed loading dvd directory." error, further in the log file is line
ERROR: Playlist Player: skipping unplayable item: 0, path [smb://NAS04/movies/The Very Best of XYZVIDEO_TS/VIDEO_TS.IFO]

I believe this is an error with how this file path is being passed to the filter.
i.e. the "smb:" should not be on the front of the path name.