It is possible to specify how subtitles appear and disappear.
You just need to specify a transition and the kind of effect to use.
You need to add 2 tags:
•Tag "Fade-in on" indicates that the transition effect will be fading.
•Tag "Transition-in duration" specifies the duration of the transition.
If you also want to fade out, you need to add a "Fade-out on" and "Transition-out duration" tags.
The order of the tags is important.
The Transition tags must be added after the Fade ones.
If you want to specify a fade, but you do not want the subpictures to be faded, use the "Transition affect" tag to turn off opacity.
This is important if you are rendering our images. Otherwise the images may be totally transparent.