Alternating scanlines with 480/576i sources

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  • November 8, 2016 at 6:32 PM #9474
    markiemarcus
    Participant

      I’m experiencing a strange rendering issue with this mode on both the scart and component input. My TV allows for the correcting scaling that avoids moire patterns on regular scanlines and those work brilliantly. The alternating scanlines mode however shows strong moire and fixed fine lines; it doesn’t look right to me at all. Same issue across multiple screens. I’ll see if I can link an image of it below. Any help or suggestions would be appreciated!

      https://s13.postimg.org/jv3elh9zb/IMG_20161108_013541.jpg

      November 8, 2016 at 9:50 PM #9480
      BuckoA51
      Keymaster

        I wonder if this is because you’re using PAL material? I’ll ask Markus to chime in here.

        November 8, 2016 at 9:59 PM #9482
        markiemarcus
        Participant

          Appreciate that, thank you. Definitely possible! Unfortunately I don’t have any native NTSC consoles to test. Although it isn’t strictly speaking NTSC, it’s still present in PAL 60hz mode on PS2 via RGB scart and Gamecube games via component on the Wii.

          November 9, 2016 at 12:58 AM #9488
          marqs
          Participant

            Does any of your screens allow 1:1 pixel mapping? I can guess that displays’ internal scaling may potentially ruin the result.

            November 9, 2016 at 2:10 AM #9492
            markiemarcus
            Participant

              Thanks for getting in touch! My monitor does 1:1 but the results are different. In ALTERNATING SCANLINE mode I get VERTICAL banding in addition to the alternating scanline effect, which makes no sense at all. Furthermore, at 50hz there is noticeable strobing with alternating scanlines that disappears at 60hz. Regular horizontal scanlines work perfectly on both the monitor and TV using its exact integer mode (4x480p with black bars). Disabling scanlines altogether also works fine. Here’s an image of 1:1 using alternating scanlines:

              https://s11.postimg.org/y70ovtecj/IMG_20161109_005127.jpg

              Again, it could very well just be bad scaling, but these seem like odd results for 1:1 mode…

              November 16, 2016 at 10:48 AM #9618
              BuckoA51
              Keymaster

                I gave them a try on my setup using PS2.. they look… okay I guess. You still get the flicker from the bob deinterlacing though, plus you can really see on the VP50 where some scanlines are thicker. It’s hard to capture with a digicam to the TV but I tried…

                alternating scanlines take 2

                This is going OSSC->VP50 Pro->TV

                I don’t think this is going to get any better with a line doubler. You’re going to need to use a full blown video processor if you want better results. Or better still just avoid interlace games wherever possible.

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