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Sometimes when playing along to music, you notice that the recording is transposed not by a semitone or a whole tone (whereby you could just play along on any normally tuned instrument), but by an interval that requires tuning down/up by a quarter tone. I have noticed that it is commonly found in movies.
My question is, quite simply: why?
log (25 / 24) / log (2) * 1200 = 70.67, so the conversion of a standard movie (24 frames per second), to be broadcast on European TV (25 frames per second) will shift all pitches up 70 cents; that's one common situation that you may be referring to.
It's probably not transposed, but speeded up or slowed down by a little bit. Sometimes to fit exactly into a sequence, sometimes changed to fit better with the mood of the film at that point. With digital sound, nowadays, this is not a necessary operation to do, as the tempo can be altered without affecting the pitch. Previously, to slow a piece down (to make if fit a longer scene), would have dropped its pitch, maybe by as little as you've found.
What user12864 said, it's the PAL speedup.
Luckily, these days it's easy to reverse by telling your movie player to play at 96% (24/25) speed.
THX films correct the pitch, by the way.
