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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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.
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