OSSC Pro 1440p support?

NewHome › Forums › OSSC, OSSC Pro and DExx-vd isl › OSSC – Discussion and support › OSSC Pro 1440p support?

Viewing 5 posts - 1 through 5 (of 5 total)
  • Author
    Posts
  • March 14, 2020 at 10:54 AM #36324
    Hydra Spectre
    Participant

      I see it has HDMI 1.4 which supports up to 4K 30Hz, 1080p 120Hz and 1440p 60Hz.
      The real deal here is 1440p at 60Hz, since the following resolutions are an integer scale to 1440p:
      144p (Game Boy, Game Boy Color, Game Gear) x 10
      240p x 6
      480p x 3
      720p x 2
      1080p seems to be the only resolution missing, but it’s okay.

      1440p can probably scale well to 4K and would look great with native 1440p monitors and for 8K TVs like LG’s Z9 and ZX OLEDs, since 1440p x 3 is 4320p or 8K.

      But what are you thinking about 1440p support for the OSSC? Is it in your plans?
      What do you think about it?

      March 14, 2020 at 12:19 PM #36327
      BuckoA51
      Keymaster

        Unfortunately that’s not possible on the current hardware, we’re at the limit with 5x.

        Edit – Oops you said Pro, yes it may be possible on the OSSC Pro.

        March 23, 2020 at 6:46 AM #36502
        Hydra Spectre
        Participant

          160p is also a 9X scale to 1440p, so 1440p is one of the best upscaling resolutions for retro games.

          August 11, 2023 at 7:55 AM #57707
          uncle_chopstick
          Participant

            Don’t forget 288p x 5! Very useful for PAL Amigas, and possibly a lot more besides 🙂

            August 12, 2023 at 5:00 PM #57743
            marqs
            Participant

              You need to calculate resulting pixel clock to understand if a mode is realistic for a given HW. For original ossc, the calculation can be roughly made as follows: (H_active_out/0.82)*V_total_in*Linemult*V_Hz. That would result to following pixel clocks for 240p and 288p multiplied into 1920×1440 resolution:

              240pX6: (1920/0.82)*262*6*60 = 221MHz
              288pX5: (1920/0.82)*312*5*50 = 183MHz

              The HDMI chip in original ossc is specced up to 162MHz input clock but likely works at 183MHz if not operated in extreme conditions. 221MHz is too much for the chip and FPGA output to work reliably, but there are ways around it as pixel repetition could be used. The biggest issue perhaps is resulting 1920×1440 timings which are not close to CVT standards, thus having limited monitor compatibility. Anyway, it should be possible to add these options to v1.xx series firmware at some point.

              OSSC Pro has neither of these limitations since it has more capable HW which is also able to decouple input and output timings. 2560×1440@60 (CVT_RB) can be thus output without any specific tricks.

            • Author
              Posts
            Viewing 5 posts - 1 through 5 (of 5 total)
            • You must be logged in to reply to this topic.