The ludicrously young Chazelle, who was a mere 31 when he made the film, has already shown the ability to turn music into great cinema. Whiplash, featuring turns from Miles Teller and an Oscar-winning J.K. Simmons was the calling card, but with La La Land, the director has upped his game and hit new heights.
As our video shows, though, it was no easy task.
Ryan Gosling spent months learning to play the piano and his efforts have paid off in spectacular fashion. Emma Stone, who recently won a BAFTA for her performance in the film, also had to put on her dancing shoes and deliver a number of show-stopping tunes.
Let us know if you think their efforts were worth it.
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