OSSC Pro: Dreamcast VGA 480p A-LM 720×480 passthrough mode aspect ratio issue?

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  • July 11, 2024 at 12:27 AM #62382
    spacetime66
    Participant

      So when I try to do try use Dreamcast 640×480 VGA into the OSSC Pro and set the OSSC Pro to A-LM 720×480 1x passhrough mode the OSSC Pro detects the signal as 704×480 which results in aspect ratio error and if I set A-LM 720×480 to 1920x1080i line 1x mode for output on my HD CRT the detected signal is 1280×480 and the aspect ratio looks correct

      I’m actually not sure which one is the way the dreamcast is supposed to look like…

      Does this happen to anyone else with dreamcast?

      • This topic was modified 2 years, 3 months ago by spacetime66.
      • This topic was modified 2 years, 3 months ago by spacetime66.
      • This topic was modified 2 years, 3 months ago by spacetime66.
      • This topic was modified 2 years, 3 months ago by spacetime66.
      July 11, 2024 at 9:18 AM #62395
      marqs
      Participant

        704×480 sampling preset does not necessarily cause aspect ratio error in itself since its sampling rate is correct for DC (858), but your display may scale 480p to 4:3 instead of keeping 1:1 PAR which then does. If the display supports VGA 640×480 timings, you can change 480p output preset timings to match that from output opt -> adv. display timing.

        July 12, 2024 at 1:55 AM #62412
        spacetime66
        Participant

          So it sounds like A-LM 480p to 1080i is actually the wrong aspect ratio then as I’m actually using custom timing to output 854×480 in a 960×540 window with A-LM 480p passthrough and 480p to 1080i looks thinner than 480p passthrough to 854×480… I compared the Shenmue PC port set to 4:3 and compared to the Dreamcast outputting 480p passthrough to 854x480p on the HD CRT and it looks like the same aspect ratio…

          July 21, 2024 at 12:36 AM #62535
          spacetime66
          Participant

            after playing around more with settings I think H output timings is what determines aspect ratio if you have a fixed output resolution

            • This reply was modified 2 years, 3 months ago by spacetime66.
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