Early film music: Published when the film is released?

[Amelia.pd]

Herbert Stothart wrote the background music for the famous musical film, "The Wizard of Oz". If this music appeared in the film in 1939 is it likely that it was published then? Are films legally published the year they are released?
As Stothart died in 1949 isn't it possible that his music from "The Wizard of Oz" or other compositions are public domain?

[pml]

A recording of a musical score is treated completely differently to the score itself - so the music included in the film would have a ? or "phonograph" copyright, but the actual score would have the normal copyright © for documents and sheet music: note that the issuing of a recording (?) doesn't mean the corresponding musical score is considered to have been published (©).

If Stothart died in 1949 he would be PD in Canada by now, but was the score ever published, as opposed to recorded? Also, there would be the post-1923 US copyright to consider, which doesn't take the decease date of the author into calculating the copyright duration.

Regards, Philip