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>Because audio for 23.976fps film is playing at the same speed as 29.97fps video. Which is really interlaced video at 59.94 fields per second. 3:2 pulldown is u

• erik 4y ago
  NTSC television video is interlaced. First you draw the even lines of the image, then you draw the odd lines. Each set of lines is called a field. Originally NTSC was 60 fields per second, based on the 60hz frequency of the North American power grid. 60 interlaced fields per second is pretty similar to 30 frames per second, but is not the same thing. The interlaced signal refreshes twice as quickly, but with half the vertical resolution per refresh. When colour was added to NTSC, the frequency was shifted to 59.94 fields per second. Movies shot on film are filmed at 24 frames per second. To convert a 24fps film to 60 field per second video, something called a 2:3 pulldown is used. The wiki explanation for how this works is pretty good: https://en.wikipedia.org/wiki/Telecine#2:3_pulldown https://en.wikipedia.org/wiki/Telecine#2:3_pulldown A 2:3 pulldown on 24fps film matches the 60 fields per second of the original black and white NTSC signal, but is slightly off for colour NTSC. The original article talks about how this can lead to problems like audio desync in production workflows. Digital cameras offer the option to capture at 23.976fps. When you apply a 3:2 pulldown to 23.976fps video, you get an interlaced 59.94 fields per second video.
  • grouchomarx 4y ago
    Fantastic. Thank you