The background option in dvd-slideshow sets or displays the background image.
The default background image can be set on the command-line in the following way:
dvd-slideshow -b background_image.jpg inputfile.txt
or, it can be set within the input file using the syntax:
If the duration is nonzero, then the background image will be displayed for that amount of time in seconds. If the duration is 0, then no image will be displayed, but the background image will be set for later use.
Subtitle is optional. Most people probably won't want to use a subtitle in this case anyway. For no subtitle, just leave it out, but keep every colon:
Used with the following effects: