Projects saved in Cyberlink PowerDirector (.pds) may be exported to several multimedia formats, including MP3, however this will produce audio only file.
There doesn't seem to exist any other program that would otherwise support .pds projects, so PowerDirector is your only choice for this particular type of pds to mp3 conversion.
Important Note: You will of course also require the relevant multimedia data which are references in the project, without them it will be most likely impossible.