The Hotel Rwanda star plays Davis in the film, which he also directs, and co-star Ewan McGregor admits it was often tough to understand the man behind - and in front of - the camera.

The Scottish star tells The Hollywood Reporter, "It was like I was directed a little bit by Miles Davis. When people ask me about this movie, I always say, 'I made this film with Miles Davis'."

But Cheadle admits he occasionally had to drop his character's raspy whisper to make sure some cast members knew what he wanted them to do.

"If the actors were too far (from their role), I'd have to raise my voice and Don would have to come out and be like, 'Over here!' Then I'd go back into my whisper."