IMSLP Forums

I found this lovely little piece, "Core 'ngrato" composed by Salvatore Cardillo who died in 1947. I was thinking about making an arrangement of it myself for commercial purposes but was worried about the copyright. I know it extends 70 years after the death of the copyright holder, which would mean it's been in the public domain since 2017, but I am unsure if there can be other things that can hold the copyright further. For example, if a composer writes a song for a film, and 70 years later after his death would the copyright expire? Or will the studio hold the copyright? Would it never expire if the company never dissolves? Or will it expire when every person involved in the production of the piece dies and 70 years pass?