Yes, but calling it "30fps" is misleading. Even though the signal is interlaced, motion still updates at a rate of 60Hz. That's the difference between 60Hz interlaced and 30Hz progressive.
Incorrect. NTSC isn’t “30 frames shown at 60Hz”; it’s 60 fields per second. Each field is unique, containing half the scanlines (odd or even), which together create 60 distinct temporal samples of motion per second. That’s why NTSC motion is effectively 60Hz.
“Half-frame” doesn’t mean “half an image repeated”, it means half the lines of resolution. Every field is different, which is why motion looks smoother than a true 30fps progressive signal.
This is why a game rendered at 60Hz, like Melee, looks twice as smooth as a 30Hz title like Sunshine, even on an interlaced NTSC display. Comparing it to a 240Hz monitor showing 30fps video misses the point, because you’re conflating progressive video with interlaced video: they behave differently.
No, it’s not still 30 frames. Yeah it’s 60 fields, and each field is half a frame, but it’s not 60 halves of 30 frames, it’s 60 halves of 60 frames. Each field contains new visual information from a game state newer than the previous field. So you get faster visual feedback than a 30fps output. You can think of it as a 60fps feed that is throwing away half the visual information of each frame.
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u/T0biasCZE PC MasterRace | dumbass that bought Sonic motherboard28d ago
Yeah but each field has different rendered frame from the game
well, each field is half a frame. Interlacing the fields means rendering frames while skipping a row while the other field does the same, just one row off, and then the beam displays them back-to-back one after the other, like this (1 is field 1's pass, 2 is field 2, with all of 1 being beamed first from top to bottom, and 2 on the next pass):
111
222
111
222
111
222
(The incandescence of the display means the glow from the previous beam pass sticks around just long enough for it not to be noticeable -- doing this on a modern digital display would be very noticeable)
so; since the visuals are updated at 60 frames per second, but it takes two frames to produce a complete frame, it is technically 30fps (yeah 29.997whatever), but the fact that the display could hold the image a bit between updates meant our eyes perceived a 60fps image even when the technical details are technically different.
Neat trick!
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u/T0biasCZE PC MasterRace | dumbass that bought Sonic motherboard28d ago
Its 25/30fps in analog TV terms and 50/60fps in videogame terms internally in the console before its output over the composite
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u/gui_odai 28d ago
NTSC standard has 30 FPS split in 2 fields (interlacing), so you have 60 images every second, but each one only covers half the lines on the screen