When I see shows from America being on air on a British TV channel (I watch on the BBC), I noticed that the sound of the films, music or in general, they go up by one. Why does that happen?
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Movies (and some, but not all modern US TV shows tend to be shot at 24 frames a second)
British TV runs at 50hz thus to fit nicely in with the refresh rate they play the movie at 25fps.
This results in a tiny speed increase, and also audio pitch shifting up ever so slightly.
It has to do with the [telecine](https://en.wikipedia.org/wiki/Telecine) process where film gets converted to another media. In a mastered film strip, the film itself is a long ribbon of plastic with sprocket holes cut into it at regular patterns. In the center of the film strip is the series of still frames that when played at the same speed that it was recorded at will show smooth motion (Provided it’s running at about 24 frames per second – has to do with some compromises persistence of vision and some limitations on how long you wanted to be able to shoot in a single run before changing out recording magazines in cameras). The audio however, has to go somewhere. It was crammed into what was previously unused margin between the video frame and the sprockets. **The pitch of the audio is married to the playback speed of the film strip – play it slower and the pitch will go down – play it faster, the pitch goes up.**
When they converted film stock movies (analog) into the at the time best possible magnetic master tapes (also analog) they had to adjust the frame rates in such a way as to cram 24 FPS motion film into 30 FPS video (US) or 50 FPs (PAL) for most of Europe [I forget what standard French used for SECAM but it may also be 50 FPS]. The frame rates of the video were themselves dependent on the frequency of the electrical generation of the countries involved. To get the 24 FPS to fit into the target framerate, schemes were devised to double frames in set patterns to fill in the missing frame info. The audio would then be dubbed back over the finished master played from the original recording. This would potentially introduce slight timing errors on the order of a fraction of a second vs when the audio “hit” in the original film due to it being possible an off frame but nothing you would likely catch.
The telecine process, when done right, was very expensive – however, you could fake it on the cheap by just playing back the film at a speed higher than intended while recording your tape master. It’s possible that the rebroadcast are from the “cheap process” tapes.
American TV is 59.94 fields per second, while British TV is 50 fields per second.
Movies are shot at 24 frames per second.
So in order to broadcast a movie:
1. If it’s for British TV, 24 and 25 are so close to each other that you can just get away with speeding up the movie by ~4%. While this gets unnoticed for video, you can hear the change in audio pitch, especially if a song you know is playing in the film. After the 24fps to 25fps speed change, you just double each frame so it’s 50 fields per second.
2. If it’s for American TV you can’t get away with speeding it by 25%. So a process called 3:2 pulldown is used. First you slow it down by 0.1% so you get 23.976 frames per second and then you split every frame into two fields and every second frame into two fields with one duplicated, so you get a 2-3-2-3-2-3.. pattern and with that 59.94 fields per second with only 0.1% speed change.
So why aren’t British TV shows faster when broadcast on domestic TV? Because they are shot at 25 frames per second and then you just have to duplicate each frame to fit into 50 fields per second. While American TV shows are shot at 24 fps.
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When shows are syndicated in the US, I noticed a higher pitch on some channels. This is because they speed up the show slightly to squeeze in more commercials.
beside what has been mentioned here already with FPS differences it may also be another reason that some channels simply show any movie sped up by 10% because that allows you to fit in an entire extra ad break.
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Me and my girl watch movies over discord, could this explain why she somehow is always drifting ahead of me even though we start at the exact same time? She’s in Australia
A lot of modern TVs in the UK can do 24fps when paired with the right source, for example my old Sony does it with certain Blu-rays, can’t tv channels do that?
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