[MPlayer-users] Does -dumpsub work?

[Giacomo Comes]

In the man page of mplayer there is the option -dumpsub
that I cannot figure out how to use it and what it should do.
The description in the man page says:
	Dumps the subtitle substream from VOB streams

If I execute the command:
	mplayer dvd://1 -dumpsub
MPlayer exits immediatly with the message:
	demux: File doesn't contain the selected audio or video stream.
I have added -sid, -aid, gived the vob stream instead of dvd://
but the results is always the previous error message.

Does somebody know if -dumpsub can do something?

Giacomo