For better quality of subtitles (except vobsub), using RGB32 as output colorspace will help.
ffdshow will try to find an external subtitles file automatically. Subtitles files usually have the same names (and different extensions) as the video files. Specify a directory to search subtitles in. One period (the default) is used to specify the same directory of the video.
In the given directory, among files that have extensions ffdshow supports, closest match by a certain algorithm will be used. Extensions priority is ignored.
In the given directory, among files that have the same name as the video file, a file that has the extension with highest priority will be used.
With heuristic search unchecked, you can specify priority of extensions.
You can explicitly specify external subtitles file here.
If checked, changes to the subtitles file are reflected on the fly.
If this is checked, ffdshow accepts embedded subtitles even if “Subtitles” is unchecked so that users can toggle subtitles during playback. If you want to other DirectShow filters handle embedded subtitles, uncheck this.
DVDs subtitles are usually bitmaps which have poor quality. Some DVDs have text subtitles embedded in their MPEG-2 streams more than just bitmap subtitles. They are called closed captions. As they are text subtitles, you can control font, size, color and so on. They are usually English. Please make sure to decode MPEG-2 in ffdshow to use this feature. To disable bitmap subtitles, use the menu of DVDs.
To move subtitles below the image, turn on letterboxing to desired aspect ratio.