I love Blow Out, it's a criminally underrated movie.
It is indeed based on Blow Up, or rather heavily inspired by it. Only in this movie the central theme revolves around sound rather than picture, with Travolta's character playing a movie soundman who witnesses and recorRAB a car accident, which proves to have sinister undertones.
Though what looks initially like an accident, the characters trained ears hear what sounRAB like a gunshot blowing out the tyres. He rescues a girl from the flooding car, but the driver dies. When the driver turns out to be a senator, and the girl in his car plainly not his wife but a call girl, a conspiracy theme starts to emerge.
There are some great in-jokes too, because Travolta's character works as a soundman for a cheap, tatty producer who makes dreadful, cheap horror movies...which are hilarious!
Then you have an early role for John Lithgow as a psychotic killer, and a wonderfully seedy turn from Dennis Franz (NYPD Blue) as a scruffy pimp.
What really grates with me is that this whole movie is based on the concept of sound, it is central to the core of the movie. Yet almost every video and dvd release of the movie has been poorly inadequate, with tatty old 2 channel stereo or even mono sound mixes. And the picture is no great shakes either, and this being a Di Palma movie there are many great widescreen tracking shots to savour.
Would love to see a blu ray restoration of this movie.