240p passthrough resolution?

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  • November 20, 2018 at 4:03 AM #23819
    marsh
    Participant

    When using 240p content on the OSSC using the pass through function my TV (on hdmi) reports the resolution as 720x480i. Is this output intended? That’s a 16:9 ratio. For 4:3 shouldn’t the resolution be more like 640x480i? I tried changing various settings but nothing brought the resolution to 640x480i.

    Using analog connections directly into the tv, it displays things fine. I don’t think it explicitly says the resolution however. But the aspect ratio is off with the OSSC and can only be fixed with the TVs resize function.

    I ask because from what I’ve read the pass through function only digitizes the signal so it seems weird something was changed in the output. Although this works with one of my TVs it confuses another since 720×480 seems to be an odd resolution. Unless that’s just what it’s supposed to be. Is this the intended output of pass through 240p content?

    November 20, 2018 at 4:38 AM #23821
    Anonymous
    Inactive

    It’s likely just how the TV is handling the 240p which it doesnt support on hdmi. What console or consoles are you trying to pass through?

    November 20, 2018 at 5:01 AM #23822
    marsh
    Participant

    It displays the same resolution for 480p content as well. I’m getting the impression the OSSC isn’t outputting a traditional hdmi signal and is somehow “hacking” it to get the desired result. Either that or I just haven’t set it up right. I’m using it for a snes. All of the line doubling options seem to work fine, it upscales the output as necessary. It’s just the pass through that seems to be acting odd.

    November 20, 2018 at 7:25 AM #23823
    nmalinoski
    Participant

    A 720-wide frame is entirely normal and expected; there may be only 640 active pixels, but the standard frame shape has been 3:2 (not 16:9) for SD and ED content for a very long time. It’s DTV, not VGA. Read up on 480i and 480p.

    It’s also not unusual for TVs to not accept 240p over HDMI, as it’s not exactly an accepted standard video mode as far as manufacturers go. It’s interesting that your TV even bothers accepting that kind of signal over HDMI, but that it would interpret it as 480i (and it probably tries to deinterlace it, too) is not unexpected, as it’s an abuse of 480i (uses only the even or odd field to display content; I forget which).

    If you have a non-CRT display that actually supports 240p over HDMI, or any other inputs, consider yourself lucky. This is the entire point of the OSSC; why pass-through 240p? Line-double it to 480p.

    November 20, 2018 at 2:46 PM #23829
    Steo
    Participant

    I found the whole thing comfusing at one stage too and how that 3:2 image was 4:3 until I realised that CRTs resize/morph the pixels making them no longer square.

    I had a Samsung UE32H5000AK TV before that accepted 240p over component without reporting 480i and trying to deinterlace it, but I never did try it over HDMI as I didn’t have the OSSC back then.

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