Runtime file time

I am currently working on a hobby project to control/search/display info
in a windows application made with VB6.

Using Kodi 16.1 Libreelec.

Using jasonrpc to get movie data.
I have noticed that if i have a movie in the library that has not been played
then there is no runtime. Either in Movie Runtime or Streamdetails. Both return 00:00:00

{“jsonrpc”: “2.0”, “method”: “VideoLibrary.GetMovieDetails”, “params”: {“movieid”: 19, “properties”: [“title”, “genre”, “plot”,”runtime”,”rating”,”art”,”file”,”year”,”streamdetails”, “lastplayed”]}, “id”: 1}

Once i play the movie in Kodi , and re display the same data, the runtime
apears.

It there a Jsonrpc already to initiate reading the file and getting the runtime before displaying the data

or will i need to check files and try to extract the runtime from the files myself.

thanks