UK Film Speed Fact Check: 25fps and Audio Pitch Explained
“in the UK used to be sped up to 25fps (film is 24fps), which resulted in the audio being slightly higher in pitch. It's likely the 'slower' version is actually the film being shown in the correct 24fps with the correct audio pitch.”
Summary
Historically, UK PAL broadcasts converted 24 fps film to 25 fps by speeding it up about 4 %, which raised the audio pitch and shortened the runtime. Modern versions that run at the original 24 fps retain the correct pitch, confirming that the slower version reflects the proper film speed and audio.
Sources 57 searched
- Proceedings of the Institute of Acoustics Vol. 38. Pt. 2. 2016
Proceedings of the Institute of Acoustics · Vol. 38. Pt. 2. 2016
- Correcting the speed of American programmes - Page 2 - TV Forum
Modern phones and computer editing software is often set to 30fps because of Hollywood/US influence which is fine on your screen, but as soon as it's transmitted on a UK TV programme - unless it's been adjusted - will flicker like hell. That will also explain why older feature films shot the ...
- Correcting the speed of American programmes - TV Forum
One rare example of the latter was Torchwood: Miracle Day, presumably because it was thought that UK audiences would be too likely to notice the pitch-shift on the familiar character's voices. It made it an ache to watch for me, though, as years of video work has left me sensitive to stuttering video. (Fresh Prince shouldn't have suffered any of this, because it was shot and edited on video, not film.
- US - UK frames per second — Digital Spy
I think they used the same thing on "24". Fortunately, for series 6 of Buffy they're using the proper speed up by 4% approach. The downsides to the speeding up is a shift in audio pitch, and shorter programme lengths.
- Help needed with 24fps to 25fps Pitchcorrected 5.1 - Gearspace
24/30 is film speed. there are 3 main speeds. its a simplified audio version of course. the different is about 4% faster in pal so pal files will be shorter. and since it goes faster the pitch will change so a pitch change is needed.
- Change from 25fps to 24FPS | Community
To fix the audio pitch, export the audio from the 25 fps timeline and use Audition to change the pitch by stretching it and using a pitch filter.. You want the length of the 25 fps audio to be the same as the duration of the 24 fps timeline.
- Programme Extraction, Transport Stream Analysis and transportx Package | hummy.tv
Although I have to agree that examining the .ts file isn't likely to further the evidence. The contents of post #1 should be enough. Whether they do anything about it . ... Click to expand... Chewing this over with other members of the BBC Engineering Facebook group, it's likely we've identified the problem with the programme, namely production at 24fps and then poor conversion to 25fps.
- What is the fps of various sources? | AVS Forum
24P video is commonly slower by .1% @23.98fps to match the NTSC standards pulldown. Conversion from 24P to 25hz has often used a 4% speedup. Audio pitch is usually compensated. This may be why some cuts seem faster. Obviously material shot at 25fps wouldn't be affected this way.
- theatres in the UK... 25fps or 24? - Avid Pro Audio Community
theatres in the UK... 25fps or 24? Post - Surround - Video
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