To play DVD video discs, you need the MPEG-2 and AC-3 (and / or DTS) video and audio decoders. These decoders are distributed with commercial DVD players. You will need to install some commercial DVD player before you can play DVDs in Subtitle Processor. SP only uses the filters available in your system, it does not have any filters bundled. You can try to search Internet to get some free DVD filters.
If you are able to play DVDs in Windows Media player, then you will be able to play them in Subtitle Processor.
There are 2 commands in the DVD open submenu: Open and Select drive.
Using the Open command you should open the VIDEO_TS.IFO file that resides in the VIDEO_TS folder on the DVD disc.
The Select drive menu contains all CD/DVD drives in your system. Note that the drive descriptions are displayed in your Windows language, not depending on the language file loaded in SP. When you select a drive and click OK, SP will automatically open the \VIDEO_TS\VIDEO_TS.IFO file on that drive.
Both these commands are also available from the OSD Main menu.
DVDs are treated as all other movies in Subtitle Processor. They are played in the same Player window as other movies. In the DVD mode however there are additional controls for the DVD functions.