We watch a lot of British TV shows (tonight, Shakespeare: Rise of a Genius). My wife commented on the ‘sparkles’. British TV shows’ costumes and lights have specularity, where the tiny lights seem to sparkle in a regular pattern. Here’s what I know:
- A/C power in England is 50 Hz. A/C power in the U.S. is 60 Hz.
- Video in England is 25 frames per second. In the U.S., it’s 30 fps.
- The U.S. standard film speed is 24 fps. In Europe, it’s 25 FPS.
So this twinkling must be because the original recording is probably 25 frames per second video; and that when it it converted to 24 fps, there are frames that get an extra bit of exposure. Is this correct?
(I only shoot 24 fps, and video conversion is up to someone else.)
I don’t know what you mean by sparkling. It’s not something I ever noticed watching British TV shows in America. Perhaps you could suggest a program where you found it especially prominent.
The suggestion that there are frames of film getting overexposed due to converting frame rates - that I can say with certainty does not happen. If it did, you’d see one sparkle every second, and any smooth action would have a stutter in it which would be more than distracting.
Films shot for cinemas use 24 frames a second universally. In the UK and Europe where PAL is the standard, TV programs shot on film and intended for TV only are as I understand it shot at 25/sec. so no conversion is necessary. Films shot for cinema projection, when run on television, they simply run slightly faster and hope no one notices. At least, it used to be done that way - maybe now they use digital processing to avoid doing that, as even a slight speedup in the soundtrack is noticeable and must be annoying. Someone else will have to answer that, as I’m not familiar with how it’s done.