Certain version of Pinnacle Studio used .st4 files to store projects, saved work in progress. Generally speaking, you can export Pinnacle Studio projects to several multimedia formats, including MPEG-4. The catch here would be to find which version of the software used this project file type and can work it, unless the latest version of the program support all the previously used formats.
Convert Pinnacle Studio 400 project file to MPEG-4 video file format.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert st4 to mp4 on Windows
A professional video editing application
Convert from st4 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.