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From: Peter van Merkerk on 17 Jan 2006 13:16 Jason wrote: > A936(a)hotmail.com wrote: >> Those are big numbers but I think you are seriously overestimating the >> processor equivalent of the c64 sprite hw. > > Actually, i'm *under* calculating because i'm assuming 16x16 pixel > objects at the Spectrum end; that's only two thirds the size of the > C64's hardware sprites. Actually it is closer to half the number of pixels (16x16 = 256, 24x21=504).
From: Chris Cowley on 17 Jan 2006 13:17 On Tue, 17 Jan 2006 16:51:36 GMT, The Starglider <thestarglider(a)wibble.co.uk> wrote: >On Tue, 17 Jan 2006 15:25:49 +0000 (UTC), Pasi Ojala ><albert(a)pikkukorppi.cs.tut.fi> wrote: > >>On 2006-01-17, The Starglider <thestarglider(a)wibble.co.uk> wrote: >>> That's just nonsense though. If that were the case, any television in PAL >>> territories would look wrong, which it doesn't. >> >>PAL is 50 Hz. Every sports show is 50Hz interlaced. > >Yes, but it's two of the same image interlaced, so the result is a total of >25fps. It isn't, you know. The two fields are different - there wouldn't be a lot of point transmitting two interlaced fields if they were both exactly the same! -- Chris Cowley
From: Pasi Ojala on 17 Jan 2006 14:01 On 2006-01-17, The Starglider <thestarglider(a)wibble.co.uk> wrote: >>PAL is 50 Hz. Every sports show is 50Hz interlaced. > > Yes, but it's two of the same image interlaced, so the result is a > total of 25fps. No, really. Sports is always shot 50Hz interlaced, not 25Hz progressive. One field is captured, and sent, another is captured and sent. 50 fields per second. Fifty fields per second. 50. fields. per. second. (Except 60 in NTSC.) And what do you mean "the same image interlaced"? That does not make any sense at all. Even in progressive: not the same image. Different lines of the image. And when it is 50 fields per second, it means if there is movement, there is movement 50 times per second. Remember, I was talking about 50Hz interlaced. I was specifically NOT speaking of 25Hz progressive, transmitted as interlaced. Movies are another thing completely. 24fps movies are shown in PAL as 25Hz progressive (4% too fast), although they are transmitted in the 50Hz interlaced format. In NTSC you get so-called pull-down, where one 24fps frame is shown for 2 fields and the next is shown for 3 fields. That converts the 24fps to 30fps exactly, although you get other problems like jerky movement because of this pull-down. (See e.g. http://www.iki.fi/leopold/AV/FilmToVideo/) > I did an experiment here: > > http://www.thestarglider.pwp.blueyonder.co.uk/fps/ > > Here you will find 4 videos of exactly the same thing, each running at 17,24,25 > and 30fps. Each video is 15 seconds long, and are encoded in XVID format. You > can see that even at 24fps, a pan of a cube across the screen is smooth. 17 is jerky. 24 is acceptable, if your display is 24fps. Otherwise you see a ghost image, because the display shows the image twice (or more) in the same location, but your eyes have followed the movement and expect the cube to be in another position. This happens in movies also, because each frame is shown twice (48 Hz) or three times (72 Hz). Otherwise you would get terrible flicker (because of the illumination properties of the projection system). Because of this ghosting (and jerkiness for rates that do are not integer fractions of the display rate) you really should always update at the native display frequency. C64 and VIC20 games normally are 50fps because they update their display at that rate. Their displays are 50Hz progressive (312 lines), although you can get interlaced out of a (NTSC) VIC20. > Hell, even at 17fps (generally accepted to be the lowest you can move something > and fool the human eye into smooth motion), the cube moves with quite acceptable > smoothness, so your theory of a pan in film is quite wrong. What theory? I said that some people don't see it, 24fps is perfectly fine for them. -Pasi -- "Everything changes, Aram." /He had just never thought that he would have to change, too./ -- Perrin in The Wheel of Time:"The Path of Daggers"
From: Daniel Mandic on 17 Jan 2006 16:29 The Starglider wrote: > Okay, faster versions are now available to view. > > Do remember this though, a movie shown on a TV is shown at the > framerate of the TV system it's on. In the UK, television stations > will show a 24fps film at 25fps, and the same happens to NTSC areas > too. > > So anyone who is thinking of looking carefully at a video (DVD is > fine) will not get an accurate comparison. I don?t know. I prefer a standard VHS. It?s not sharper but more calm and the sound-quality (Hi-Fi) is more than satisfying (I am still listening FGTH with VHS, recorded with an old tuned [AT OC9.... SME.] Record Player aaeehh Turntable). S-VHS with its higher bandwith can compare in sharpness (easy), not to mention the analog-class it still have, makes camera pannings more smooth than DVD, and even Standard VHS. The Standard Video, PAL, PAL+ or NTSC, it does not matter, consists of four compressing stages (IMhO) without the (today) known data-reduction effect. The only effect is that it saves even more bandwidth and blows the picture four times up, at once. And after all that compressing and decrompressing the side effects get even more. Splendid. Best Regards, Daniel Mandic P.S: One of the best things in the times of Speccy and XL, C64 and so on was, that the TV-Stations had a good Broadcast Quality. Well, German Public TV Stations are great, till now. P.S.S.: I know I write much about this TV stuff... but I like it, and the Speccy with its nice black (w/o bright) is a good thing to connect to.
From: Daniel Mandic on 17 Jan 2006 16:41
Pasi Ojala wrote: > What theory? I said that some people don't see it, 24fps is perfectly > fine for them. > > -Pasi Yes, of course. It exceeds the frame-rate of any known human. 19 maybe 20 is the maximum..... I would say. Mutants not included :-( The World consists of that framerate your eyes and brain are capable of. Some see more pictures in the same time, other can see lower but therefore maybe more details. The Nature compensates itself, a weakness is a Strenghth, and otherwise as well. Best Regards, Daniel Mandic P.S.: 25 came from 50HZ Electric Frequence. 30 Ntsc from 60HZ Voltage. |