The only way to produce .dsb projects is to of course use the WonderShare DVD Slideshow Builder which is the software that uses this type. It accepts all kinds of multimedia data, including MPEG-4 (both audio and video) saved usually with mp4 extension.
Convert MPEG-4 video file format to WonderShare DVD Slideshow Builder project file.
We found one software available in the database for this conversion.
Microsoft Windows software - convert mp4 to dsb on Windows
A program for making DVD photo slideshows
Convert from mp4 file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.