The NES, and many other early computer/game systems, don't bother sending an interlaced display. Basically, they omit the half scan line at the end of one frame that positions the next frame lines in between the prior frame.
That's what 288p is.
And the result is half the vertical resolution but at full frame rate. 50fps
Pal, intended for viewing movies, television broadcast does output that half scan line for the full vertical resolution, and the result is a full frame is seen every other frame.
That's what 576i is.
Twice the vertical resolution, half the frame rate or 25fps.
Ok, so standard PAL is 25FPS, but half vertical resolution PAL is “50FPS”. Thanks for the detailed explanation of why you call it 50FPS (as seen from game’s perspective, not the PAL spec as GP implied).
> And the result is half the vertical resolution but at full frame rate
This is incorrect. It would be correct if you said “full field rate” here. The PAL standard is 50 fields per second. Two fields comprise one frame.
Now as to the NES specifically, this link breaks down more precisely the game’s FPS (tl;dr, it’s neither PAL or NTSC’s frame or field rate exactly):
You should consider editing the downvote comment away. Wasn't from me, and my advice is to just ignore all that. I do.
Yes, that article is right about the timings. The signal standards were abused in small ways to improve graphic quality, get speed and more.
Similar things happen in NTSC land too. Those deliver 60 fps. Many TV sets will permit further abuse and deliver NTSC with more PAL like timings to get 50fps, but still with NTSC color encoding.
An Amiga and Color Computer 3 can both do this. It is correct to do in some parts of the world too. I have done it in video signal projects.
Whether my comment is incorrect depends on POV.
From the NES pov, and how gaming generally thinks of frames, its fine.
From the signaling POV field is more descriptive.
Consider when there is no interlace, what happens to the concept of a field? There aren't any. Just frames, as in one complete image completely displayed.
Many people think in simple frames per second terms. This is why many, particularly those who grew up during retro times, will say PAL 50fps. To them, PAL does in fact deliver 50 complete frames per second.
Edit, oh yes! I do see where I should have said field early on. Too late to edit now. Basically, when the half scanline is not part of the signal output, fields go away.
When it is, there are fields and they get displayed sequentially, interlaced fashion, one full frame displayed every two fields.
> This is why many, particularly those who grew up during retro times, will say PAL 50fps. To them, PAL does in fact deliver 50 complete frames per second.
That doesn’t make it correct, but I agree now in retrospect and thus edited my post.
(Also, agree re: intro part to your reply. The problem I have is when factually correct comments without anything wrong about them get greyed out)
Ignore it. Over time you get thicker skin, handle exchanges better[1], as I did here, and your net upvotes go up
Yes, not worrying about it improves it. Strange world sometimes, isn't it?
[1]not saying you are bad. No judgment here. And that's the point. I basically don't do judgment and treat you the same way whether I see upvotes or not. That really improves things.
BTW, some contributors to that forum thread are incorrect about interlace being about the number of scanlines.
Interlace requires there be one half scanline.
Whether there are an odd or even number of scanlines can impact color phase shifting, depending on whether the source signal is phase shifting the color burst.
Older machines, such as the 8 bit Apple 2, did not phase shift at all so color artifacting would be predictable and useful. Even vs odd scan lines would affect precise frames per second only.
PAL is 25FPS, no?