Kenneth Branagh has admitted he did not know much about opera before directing his film of Mozart's The Magic Flute.
Branagh's opera is also being shown at the Toronto Film Festival
"I wasn't very familiar with opera full stop. But I started educating myself slowly," he said.
He was speaking ahead of a Venice Film Festival screening of his £15m movie at the city's La Fenice opera house.
Branagh, 45, said it was "provocative" to set the film during World War I but that he hoped it could say "something meaningful about peace".
He heard "a kind of plea for peace" in Mozart's music, he said.
Branagh, who also appears in the film, admitted he was initially unfamiliar with The Magic Flute, which was first performed in Vienna in 1791.
"Although the comedy and the charm of the music hit me first, I was struck by the intensity and the drama of it."
The adaptation, based on a screenplay by Stephen Fry, depicts the 1914 Christmas Day truce when British and German soldiers played football in No Man's Land between the trenches.
"Whatever piece of art you attempt, you try and bring your own originality to it," said Branagh.
Novice actress Amy Carson won the film's key role of Pamina straight out of university, with no previous experience of performing professionally.
"Ken has such an enthusiasm and energy. To work with him has been a great joy," said the 23-year-old.
Branagh's previous films include Dead Again, Peter's Friends and the Shakespeare adaptations Hamlet and Henry V.
The Teatro La Fenice opera house re-opened in 2004 following a fire in 1996.