Did you wonder why Whiplash was nominated for Best Adapted Screenplay rather than Best Original Screenplay at the Oscars?
That's because director Damien Chazelle originally conceived it as a short film, which focused in on one of the eventual film's best scenes - Neiman's trial by fire in studio band.
The rehearsal room was different and not lit as gorgeously, the soundtrack was yet to get its sparkling precision, Johnny Simmons played Neiman before being replaced by Miles Teller and the dialogue is a little different, but apart from that not a huge amount was changed.
JK Simmons plays Fletcher with the same intensity (and black t-shirt and hat combo), his signature 'stop' hand signal and "not my tempo" were already there and a lot of the visual cuts are the same.
Watching the 17-minute film it's easy to see why it excited producers into giving the film a full feature-length run time and how early on Simmons had the Oscar-winning role nailed.