I am remastering sound and music for a film made in the 80s which was recently converted from film to digital. Some of the music is recorded by a European string quartet, and may have been recorded at 442 Hz. In some cases 445 Hz seemed to match best. Besides using one’s ear, are there any techniques to come up with an accurate estimate of a recording’s tuning?
As an example, if I were to take a recording of a Beethoven symphony and transpose it by an arbitrary amount (.767 semitones) it seems like there should be a way to detect this via software, rather than guessing by ear. It’s primitive, but by holding a tuning app to the speaker, I was able to tell that it thought each note was consistently sharp (the app was set to 440Hz equal temperament).