SEA_Reroll

Hello there, I'm currently planning to make a new standalone modification for the game, that requires unpacking some of the in-game voice. I've found out that .idx files in the bin/<game number>/idx folder is connected to the .pkg files inside res_packages folder, however I have no idea how to connect the metadata inside the .idx files with the data inside .pkg files. Since I'm thinking that this program knows how to do such thing, can you give an insight about it? Thank you.