Sega Genesis and Composite Video

Discussion in 'General Sega Discussion' started by Taylor, May 6, 2021.

  1. Taylor

    Taylor

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    I was reading an old forum thread comparing Genesis output through composite video signals vs RGB video signals and this part made me think:

    [​IMG]

    With the sheer amount of info we have on Sonic development (and Genesis games as a whole), do we have any info on how developers would design art assets for display through composite video? It would be interesting stuff to read about if it was ever disclosed publicly.

    I admit, I've only played Genesis games through RGB, so the idea of some effects only being possible through inferior video signals never occurred to me until I read about. 90s gaming is so interesting!
     
  2. Gryson

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    Yasushi Yamaguchi (Judy Totoya of Sonic 2 fame) discussed this in that recent interview I've posted some translations of here. I don't have it with me right now, but going from memory: He said that when they first started developing games on the Mega Drive, they didn't take into account how composite output affected the graphics. They were just designing at the pixel level.

    However, when they saw how horrible the early model Mega Drive's composite output was and how it was distorting what they had designed, they started to consider it more carefully and started to design the graphics for composite output. I don't think he says when this change occurred, but it seemed to be early on in the MD's lifespan.

    So when they included vertical dithering in Sonic games, it was with composite output in mind. But yeah, this topic is a can of worms and there are so many factors at play (personal preference, MD model, CRT model, etc.).

    I'll try to get that interview posted later.
     
  3. Gryson

    Gryson

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    Here is the translation:

    Excerpt from a 2017 interview with Naoto Ohshima and Yasushi Yamaguchi (Judy Totoya) in the book Phantasy Star: 31 Nenme no Genten by Yuzumo Design
    pp. 80-81

    Ohshima: Back then, the TVs were CRTs. With the Mega Drive’s limited number of colors, we made use of the CRT’s blurriness.

    Yamaguchi: At the very beginning, we were making everything on RGB monitors, and we expected it to appear on the TV like that. But when we actually saw the output from a Mega Drive on a TV, it was totally blurry.

    ----Yeah, there were problems with red colors and such.

    Yamaguchi: As time went by, the Mega Drive’s components were revised and became more efficient, so the later Mega Drive models had less blurriness than the earlier ones. But the first models were truly horrible. We’d draw each pixel of a row individually, and it would all be blurred together on the TV. I remember thinking, “What the hell happened?”

    Ohshima: We’d use that blurriness to create intermediate colors (laughs).

    Yamaguchi: Yeah. We started designing everything to make use of the blurriness, but the surprising problem now is that recent re-releases on the PS3 or PS4 just display the pixels as-is. I want to say, “Stop that!” (laughs). Another point is that pixels on the Mega Drive are not actually square. The height is about 108% of the width. At first, nobody realized that when we were drawing art, but when we saw it on a TV, the vertical balance looked off. Once we realized that, we purposefully compressed the RGB monitor output that we used to draw the art. If you don’t do that, you can’t make correct squares. That’s what happened at the beginning when we were just using RGB to draw everything, but partway through we started to take into consideration how it would be shown on the TV. Back then, Sega was trying to save ¥100 or ¥200 on the circuits, and that led to the blurriness (laughs). The PC Engine had really sharp output so it was totally frustrating for us. I thought, “Why does the PC Engine have such beautiful output while the Mega Drive looks awful?”
     
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  4. DigitalDuck

    DigitalDuck

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    For what it's worth, back in the Spectrum days RF colour bleed would be used (along with dithering) to add additional colour to what would otherwise be monochrome games. This is something that was known about and used before the Mega Drive was even a thing, so I would fully expect Mega Drive game to use similar techniques.
     
  5. Blastfrog

    Blastfrog

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    It's blatantly obvious that the Sonic games' graphics were drawn with composite blur in mind. I really do wish that the Tax/Stealth remakes redrew the art to look as intended but in a clean display. I realize that'd take longer, you'd have to hire another artist to do all of that, and would cost more money, but I think it would've been worth it. To some small extent they did account for it on some transparent objects, but for the most part left the art assets alone.
     
  6. Black Squirrel

    Black Squirrel

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    That so-called "rainbow banding" isn't intended behaviour and from what I understand, can differ between console models* and cables and televisions. They wouldn't have been designing for that, just like CRTs might have slightly curved screens or have overscan, or were just inherently not good at showing crisp things.

    But graphics were definitely drawn knowing that the pixels weren't going to be sharp, much like the audio was composed knowing it would come out a bit softer. Kega Fusion has filters to better replicate what you actually get on a Mega Drive console, as opposed to the default "perfect" settings that the internet likes to pretend were the real deal, and it's good not just for the pseudo semi-transparency, but the 256x224 resolution mode that's set to look like liquid arse if stretched to 4:3 without filtering.


    *there's a reason earlier models read "high definition graphics" - because they genuinely are better at reproducing "defined" graphics. Consoles were kitted out with lesser parts as the years went on, but they were retailing for a lot less, and most of the audience was using RF.
     
  7. Gryson

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    Read the interview I translated above - it contradicts some of what you're saying. At least on the first MD revisions in Japan, the quality of the composite output was very poor (I've heard this other places outside that interview as well). Whether graphics were drawn with composite in mind has to be determined on a case-by-case basis. As Yamaguchi said, at first they were not taking composite into mind; it was only when they saw how awful the MD's composite was that they started to make use of composite effects more. Since he also designed games on the Master System, I assume he was not factoring in composite there either.
     
  8. Impish

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    Just looking at OP's image for a second and yeah, I think the "rainbow" tubes look more like the glass tubes I think they're intended to portray than the stale grey lines you get in RGB.
     
  9. Black Squirrel

    Black Squirrel

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    Apologies - my post was more of a "they didn't expect rainbows in Sonic 2" response than Mega Drive games as a whole - in the early days I can fully believe they weren't compensating for poor video quality.
     
  10. nesboy43

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    Just wanted to chime in and say if you use a 32x on your model 1 genesis both the RGB and composite out are much better (and takes away the rainbow banding).
     
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  11. Gryson

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    Very true - the difference is really striking and shows the lower quality of the composite encoder on the MD.
     
  12. Mentski

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    The video circuitry of early Mega Drives is one big mess, not only do you get the rainbow banding through composite (due to the CXA1145 just not being up to the job), you also get the jailbarring via RGB on the blue channel due to the blue trace being right next to the composite subcarrier on the PCB (which has become infinitely more noticeable when connecting to an LCD, but is still there on a decent CRT TV or monitor). Different VA revisions can suffer at different levels of this, but AFAIK, there isn't a single board from VA0-VA6.8 that doesn't have some kind of video issue on composite or RGB.

    (VA7 is basically MD2 hardware in an MD1 case, so has cleaner video, but that integrated ASIC MD2 sound)