Why is TV 29.97 frames per second?
Why Hacker News recommends it
Go-to explanation whenever the strange 29.97 frame rate comes up, praised for its clarity and presenter.
What it is
Matt Parker explains the history behind NTSC television running at 29.97 frames per second rather than 30, tracing it to the backward-compatible addition of color. He walks through the arithmetic behind the odd ratio.
Recommended by 4 HN commenters across 4 different months, 2016 to 2025.
What Hacker News said
Strong rec mikepurvis · 2020-10 · on “My Eight-Year Quest to Digitize 45 Videotapes”
Vaguely related, anyone who hasn't seen it, definitely go and watch Matt Parker's legendary explanation of why NTSC runs at 29.97fps: [this video]
Recommends mxfh · 2016-10 · on “The “432 Hz vs. 440 Hz” conspiracy theory”
If anyone wonders where the odd NTSC frame-rate ratio originated from, Matt Parker (standupmaths) did a comprehensive video, with some original write-up on this recently: [this video]
Recommends santix · 2018-01 · on “Color Television: NTSC Tutorials”
Cool video. I found another interesting one: Why is TV 29.97 frames per second? [0], which refers to NTSC's frame rate. [0]: [this video]
Recommends walkerbrown · 2025-12 · on “The biggest CRT ever made: Sony's PVM-4300”
For anyone this deep on the thread, check out this video (great presenter!) explaining TV spectrum allocation, NTSC, PAL, and the origin of 29.97 fps. [this video]
Cites djsumdog · 2018-01 · on “Learn FFmpeg the hard way”
That comes from the old NTSC standard and the history of adding colour in a backwards compatible way: [this video] In the case that the above posters are mentioning, this probably has less to do with NTSC compatibility and more to do with bad timing hardware or cameras that attempt to do too much in PIO mode instead of using real encoding hardware.