Dvdread: avoid a nasty crash.

modules/access/dvdread.c

@@ -801,6 +801,10 @@ static int DvdReadSetArea( demux_t *p_demux, int i_title, int i_chapter,
         /* Title position inside the selected vts */
         p_sys->i_ttn = p_vmg->tt_srpt->title[i_title].vts_ttn;
 
+        msg_Dbg( p_demux, "%i", p_sys->i_ttn );
+        if( p_sys->i_ttn < 1 )
+            return VLC_EGENERIC; /* Couldn't set title */
+
         /* Find title start/end */
         pgc_id = p_vts->vts_ptt_srpt->title[p_sys->i_ttn - 1].ptt[0].pgcn;
         pgn = p_vts->vts_ptt_srpt->title[p_sys->i_ttn - 1].ptt[0].pgn;