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Thread: Some video questions (really confused now)

  1. #1
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    Blinky Some video questions (really confused now)

    So, I've been reading some very interesting threads here at sega-16 but because my technical knowledge in also very limited my mind got messed up!

    Please bear with me for a while.


    Let's see if I can get this straight:

    The genesis/megadrive can output various screen resolutions.

    Games have to use some resolution, but it may not always be the same? I mean, the sega logo, intro, selection screens, etc, and main gameplay screen they all can vary the resolution?

    Is it possible to tell what resolution the game is running at, just by looking at the screen...?

    But, regardless of the game resolution, CRT television always show the picture fitted to 4 corners, in 4:3 aspect ratio (even if the correct resolution ratio isn't 4:3)?


    I ask this because I've been using GENS and I noticed some games are "wider" than others.
    For example, Turbo outrun looks smaller, whereas T2 arcade game occupies the game window.
    Does this mean that when we play these games, for example, on a 4:3 CRT TV, T2 arcade game is shown correctly but Turbo outrun is not?


    Now, has this something got to do with H40 mode and H32 mode?


    I read somewhere about Klax and marble madness Widescreen modes having something to do with switching H40 and H32 modes, no sure if it's actually called like this.

    Would that mean that games in H32 mode (and with its assets made for h32 mode) when forced to h40 mode would be in widescreen mode, and correctly viewed on a widescreen 16:9 CRT TV?

    Is it possible to build a H40/H32 switch?
    Last edited by MegaDriver; 05-17-2020 at 06:33 PM.

  2. #2
    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert Aleste's Avatar
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    Megadrive mainly uses two resolutions for its games, "H40" (320 pixels wide) and "H32" (256 pixels wide, like NES and SNES).
    The software can change resolutions at will and usually does: for example, logo screen, menu, cutscenes in hi-res, gameplay in low-res.

    Neither of these resolutions have anything to do with a 16:9 widescreen: all games are of course conceived to be played on 4:3 CRT TVs, the difference is that "H40" games will have smaller pixels and more pixel density, in other words, more way to cram detail into an image. That's probably what Sega was touting with its "High-Definition Graphics" slogan. Both an H40 image and an H32 image will of course be presented full screen on your television.

    A switch like the one you mention is therefore not possible, and wouldn't make any sense anyway.

    Is it quite easy most of the times, when you've got your eye trained, to distinguish the games (or the portions of a game) running in low-res from the hi-res one. As you easily spotted, the British port of Turbo Outrun is in low-res. The Hertz port of the original Outrun is in hi-res.

    If you aren't sure of your eyes, one way is to try an emulator: Genesis Plus on Mac for example resizes the window accordingly.

    Firebrandx has a pretty accurate list
    of the US Genesis releases whose main gameplay is in low-res.
    From a developer point of view, choosing one resolution over the other is for a series of reasons: may it be purely aesthetics, but more often it's because one video mode offers certain advantages compared to the other.

    One thing you can quite easily infer by scrolling the list is that when you have a low-res game that's also on Snes, that's an almost sure sign that the main development was done on the Snes, and later ported to Megadrive.



    *Not sure if this needed to open a third thread, but try to modify the title to include the word "resolution" or you won't find it easily again.
    Last edited by Aleste; 05-17-2020 at 10:26 PM.

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    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert Aleste's Avatar
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    Does this mean that when we play these games, for example, on a 4:3 CRT TV, T2 arcade game is shown correctly but Turbo outrun is not?
    Actually, both resolutions have a different ratio from 4:3

    4 : 3 = 1,33 (the "full frame" or "Academy Ratio" in cinema talk) means that base is 1,33 times the height;

    320 : 224 = 1,42. Base here is quite wider than height, almost one time and half. 1,42 doesn't have a cinema equivalent, sound movies went from 1,33 o 1,37 to 1,66. Here's however a still in 1,40.

    256 : 224 = 1,14 Base here is almost the same as height. The image is shaped in almost a square. Cinema doesn't do 1,14 but early sound movies were in 1,19 (to make some space on the negative for the audio strip). Here's Peter Lorre in 1,19

    Since the difference between 1,42 and 1,33 is much lower than the one between 1,33 and 1,19, the H40 "hi-res" mode of the Genesis is less distorted from the 4:3 output (it gets a little compressed from the sides). This means the graphic artist can be less careful and draw pretty much as he sees fit. (of course if he takes into consideration image correction it's better, especially ovals, rounds, circles etc.)

    The graphic artist working in H32 low-res mode must be much more careful because the final image in 4:3 output gets significantly more squashed (from top & bottom). I'm sure you can notice the effect playing SNES on an emulator and on a real TV.


    By the way, the PAL Megadrive also has an additional 320x240 (QVGA) resolution mode which is in a perfect 1,33 aspect ratio :-)
    Last edited by Aleste; 05-17-2020 at 11:18 PM.

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    Quote Originally Posted by Aleste View Post

    The graphic artist working in H32 low-res mode must be much more careful because the final image in 4:3 output gets significantly more squashed (from top & bottom). I'm sure you can notice the effect playing SNES on an emulator and on a real TV.


    Ok then, that's what I noticed when played Turbo outrun on my CRT TV, it looked very squashed!

    So, unless the display has geometry controls available to the user, on a TV we may not see some games in the correct proportion.

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    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert Aleste's Avatar
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    It's a misconception. These were programmed by professionists in the nineties. People that perfectly knew they were doing a console videogame, that would have been played on 4:3 TVs at home. The proportions have therefore been taken into account. Remember: there was no internet, no emulators... Programmers and beta testers were using cathode equipment too. The notion that they would overlook such a thing borders ridiculous.

    I've seen a post by sik in another thread with an image showing Super Mario World vertical climbing animation, is purposedly bulkier so that 4:3 will adjust it. It's a perfect example.

    Wherever you read that a chosen pixel ratio is "flawed" you can stop reading. These were all the tools of the trade...

    Just play on a 4:3 set-up or set your retroarch to "CRT" and It'll be good.
    Last edited by Aleste; 05-18-2020 at 08:46 AM.

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    Hedgehog-in-Training Hedgehog-in-TrainingOutrunner Stifu's Avatar
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    Quote Originally Posted by Aleste View Post
    I've seen a post by sik in another thread with an image showing Super Mario World vertical climbing animation, is purposedly bulkier so that 4:3 will adjust it. It's a perfect example.
    I haven't seen that post, but isn't it the other way around? Ie: the animation should be drawn thinner, as forcing a 4:3 ratio will make it bulkier.

  7. #7
    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert Aleste's Avatar
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    Quote Originally Posted by Stifu View Post
    I haven't seen that post, but isn't it the other way around? Ie: the animation should be drawn thinner, as forcing a 4:3 ratio will make it bulkier.
    Normally yes but here we have Mario climbing a wall vertically, which means that he is horizontal on the screen... He's drawn bulkier so that the screen squashes him. Genius. :-)

    Edit: found it
    Last edited by Aleste; 05-18-2020 at 08:46 AM.

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    Quote Originally Posted by MegaDriver View Post
    Ok then, that's what I noticed when played Turbo outrun on my CRT TV, it looked very squashed!

    So, unless the display has geometry controls available to the user, on a TV we may not see some games in the correct proportion.
    Sadly, yes.
    Some games have art originally designed for a different resolution than the one they're running on. Some artists overlooked such details; some games were just rushed out of the door with reused assets, etc.
    Fatal Fury 2 on the MD is another example. The sprites weren't reworked to be displayed at 256 x 224, so they look fatter than they should be.

  9. #9
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    @MegaDriver
    Also, you may find this video interesting if you still haven't watched it:

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    Just couple of things to note: H40 is ~0.91 pixel aspect ratio. Frame aspect ration doesn't tell you the whole story. PAR tells you exactly how big you pixel is (in a ratio of width and height), and is the most important attribute you of them all. 1.0 would be square pixels.

    "Square" pixels wasn't defined until sometime in the 90's (and was largely ignored, giving rise to some confused today). NTSC has a maximum display resolution of 720x484. For purposes of standards, it was decided 720x480 would be digital standard with a PAR of 0.909090. To used a more absolute term.. the NTSC "dot clock" frequency is 13.5mhz. Remember this number, and remember that phrase.

    So NES, SNES, SMS, PCE low res, and H32 on the Genesis are all 5.369mhz dot clock. H40 is 6.711mhz dot clock. PCE mid res is 7.159mhz dot clock, and high res is 10.738mhz dot clock. The higher the number, the skinny your pixel gets (horizontally).

    On NTSC, 5.369mhz dot clock gives you a PAR of ~1.14, 6.711mhz (or H40) gives you a PAR of ~0.91, and 7.159mhz gives a PAR of ~0.857.

    If your PAR was 1.0, then your pixel would be exactly square. The H40 zealots say H32 is wrong or "incorrect", but it's "fat". Your pixel is literally 14% wider. But H40 isn't square either! It's skinnier. If you find the average between the two.. you pretty much get ~1.02 near perfect square. Guess what system basically has square pixels? The Neo Geo haha.

    In a perfect world, your SDTVs and RGB CRT monitors, etc would all be calibrated perfectly and PAR and DAR (screen ratio) would be spot on. But guess what? Unless you had a calibrated NTSC professional monitor.. your PAR and DAR were off. I saw it first hand on many sets back in the late 80's and 90's. Not only that, but a lot of TVs and monitors (yes, VGA) had horizontal and vertical adjustments. I personally believed most TV sets were adjusted to be slightly skinnier than fatter (for obvious reasons). If anything, your old SDTV set probably made H32, or "snes res", closer to 1.0 PAR than it should have been.

    FYI - your Amiga and ST didn't have square pixels either. Also, the Easter bunny isn't real.

    What is my point in all of this? Don't get hung up on exact PAR. Chances are, even your console artist BITD using a CRT to draw graphics, probably didn't have a 2000$USD professionally calibrated TV monitor either.. or "close enough' was close enough.

    When I played these systems BITD, I had everything adjusted the way I liked it; color, brightness, contrast, H and V width, etc. Same for emulators today.


    EDIT: I figured I should give some reference:

    Tiles on the snes and genesis are 8x8 pixels. 8 pixels wide. If you use H32 resolution mode, that means for every 8 pixels across a tile, it would take up the width if ~9.12 pixels after adjusted for PAR.
    Last edited by turboxray; 05-19-2020 at 01:42 AM.

  11. #11
    Raging in the Streets Sik's Avatar
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    You forgot another detail: the PAR is different for 60Hz and 50Hz as well (50Hz puts the lines closer together, so those pixels are actually shorter). Most people will never acknowledge 50Hz in these discussions though, let alone the big bars at the top and bottom (even the rarely used 240px high mode didn't necessarily cover the screen).

    This said, something that may be more of a '90s~'00s TV thing (rather than '80s TVs which may have been more common back then), but I noticed that for NTSC they were often calibrated such that it would actually show all 224 lines at the middle of the screen (though still getting cut off at the corners since CRTs aren't rectangular), though still a bit too wide so that 320px wouldn't fit on screen. May be just me having loose memory however.

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    Hedgehog-in-Training Hedgehog-in-TrainingWildside Expert Aleste's Avatar
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    Two things: I feel like an old geezer but I'm still surrounded by scores of CRT tvs. I have two multistandard, a Trinitron and a Samsung, which are still my preferred panels for Megadrive (and Light Phaser) gaming.

    I speak for personal experience: at least here in Europe where I grew up, there was no such thing as vertical and horizontal adjustment in commercial, standard Tv sets. Not even in the high tier priced ones. This feature was totally absent at least from 1988 and on. I know because I searched them for quite a time. Of course, we had lots of computer monitor with those feature, and I personally still have two commodore 1084s.

    Anyway, as Black Tiger wrote elsewhere (i believe in the megaman x3 porting thread), it's not much a question of whether developers took correction into account (it's obvious that for many reasons this wouldn't have been feasible in every instance; although personally I'm wary of people submitting as hard evidence the presente of ovals, as if all of a sudden every graphician is a novel Giotto aiming for the perfection of circles everywhere...).
    The most relevant fact here is that, regardless of the original pixelwork, these games were all played in what is an "average 4:3 crt set-up", considering all the possible small differences that came with a lack of standards. It's that look which was the *only* real look these products had once bought from shelves and brought at home.

    Remember, we're also living in a day and age where it is still a conquest to educate new players to not go all 16:9 with retro gaming. This means there's a casual audience looking and longing for a distortion which is incredibly higher than the ones discussed on this thread so far.

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    Quote Originally Posted by Aleste View Post
    This means there's a casual audience looking and longing for a distortion which is incredibly higher than the ones discussed on this thread so far.
    I don't think most of them are actively looking for it, they just get it by chance or by default, and are okay with it.

  14. #14
    Raging in the Streets Sik's Avatar
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    Yeah, I think they end up with 16:9 because they just don't know better. They know it's distorted, just not how to fix the distortion (and decided it wasn't worth the hassle).

    Quote Originally Posted by Aleste View Post
    I speak for personal experience: at least here in Europe where I grew up, there was no such thing as vertical and horizontal adjustment in commercial, standard Tv sets. Not even in the high tier priced ones. This feature was totally absent at least from 1988 and on. I know because I searched them for quite a time. Of course, we had lots of computer monitor with those feature, and I personally still have two commodore 1084s.
    You sure? I really doubt they made any TVs without adjustments… (think about needing to readjust the TV after repairs, etc.) What you may be thinking on though is that they aren't easily accessible. I recall a lot of TVs hide it behind a service menu, which sometimes is buried behind an obscure key combination but sometimes may also require an extra piece of hardware. This usually means you need to take the TV to a serviceman to adjust the screen.

    It is pointlessly annoying as heck though, I'll give that.

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    I'm from France and don't remember such features on TVs either, but I remember them on computer monitors. It's possible I didn't fiddle enough with TVs, though.

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