Koryuu video output shimmering ?

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  • #35446
    Guld
    Participant

    I just got my new Koryuu and testing it with a PS1 console connected via composite. Since it is a US PS1, I presume it is NTSC if that matters?

    When I connect the PS1 composite to the composite input on the Koryuu and the component output to the component input on the TV. I get shimmering on some of the menu items from the basic PS1 startup (no disc inserted). However when I connect the component from the PS1 directly to the television the signal is solid and does not shimmer at all. I tried the different input selections (both composite inputs look nearly the same). I also tried pressing the option button in case I had accidentally pressed it and the video only gets blurry when I press that button.

    Additional testing: My Game Cube connected through the Koryuu via composite and S-Video looks great through all input modes.

    Any advice?

    • This topic was modified 7 months, 2 weeks ago by Guld.
    • This topic was modified 7 months, 2 weeks ago by Guld.
    #35505
    megari
    Participant

    Hi!

    Sorry for not getting back to you sooner.

    Could you tell us more about the kind of signal your PSX was outputting in each case? 240p/480i/something else?

    If the PSX outputs an interlaced signal which is then fed to the Koryuu, the output of the Koryuu should be interlaced as well (it does not attempt to deinterlace), and most TVs will apply deinterlacing to the signal.

    If the PSX output is 240p, the Koryuu should likewise output 240p. Some non-CRT TVs do not handle 240p well, but that is a bit less unlikely in this particular case.

    As in both cases you end up passing the picture to the TV through the component connectors, there should, in theory, be no categorical difference between the [PSX -> YPbPr -> TV] and [PSX -> CVBS -> Koryuu -> YPbPr -> TV] chains in terms of how the TV interprets the signal. The picture quality of a direct component connection will be much better, of course.

    Would it be possible for you to provide us a video clip of the shimmering? Also, if you have an OSSC, could you provide the information shown on the OSSC LCD?

    #35686
    Guld
    Participant

    Sorry for the late reply, I didn’t get an e-mail telling me there was a message despite being subscribed.

    How do I check what signal is being output from the PS1? I was using the original connection adapter that has composite, and left/right audio RCA outputs. I have also tried a generic adapter that also includes S-video. Interestingly enough, the S-video output looks great.

    It only seems to be that one screen that looks at all strange though, everything else I have tried looks perfect.

    Here is a link to a video, which unfortunately makes the image look far worse than it actually is due to compression artifacts. But if you look at the “R” above Memory Card you can see where the green box and stray green pixels bounce around a little bit (again, try to ignore the compression artifacts). It is not obnoxious and may even be what it originally looked like, so feel free to tell me that’s how it’s supposed to look :). It’s been a while since I’ve seen the unit plugged into a CRT.
    https://photos.app.goo.gl/TrmR9gWaCsBrDU9eA

    I tried to capture the OSSC screen in the video but it didn’t quite take. It says:
    AV2: YPbPr 525i
    15.72kHz 59.90Hz

    #36065
    megari
    Participant

    Thank you for your response and sorry for mine being late again. The video and the information you provided gave some clues.

    The video input (and thus also the output) seems to be pretty much standard 525i NTSC. From the video it seems as if this could be a problem with field reversal, as details in the supposedly static elements of the UI are constantly “twitching”.

    On the other hand, the shimmering could be caused by the inherent weaknesses of composite video signals. For instance, this Youtube video seems to show a similar effect, although the video is rather blurry and I don’t know how it was captured: https://www.youtube.com/watch?v=i_HYGZtGQTw

    S-Video constantly looking good suggests that this might simply be a particularly bad case of composite artifacts caused by luma and chroma channels interfering with each other. Could you try and check if you can make the shimmering effect appear with S-Video, please? That should allow us to make a more educated guess at what might be going on.

    #36369
    Guld
    Participant

    Megari,

    Yes, that youtube video you linked is what I see if I use the composite output. I don’t know how to get the S-video to output that way. Do you have any suggestions for how to make it appear?

    #39506
    Jarrah White
    Participant

    Sorry to bump up this old thread. But I was watching My Life In Gaming‘s episode on the Koryuu and noted that Try was also getting the field reversal issue on interlaced games. Has this issue since been solved?

    #39509
    megari
    Participant

    Jarrah White, debugging the field reversal issue has been delayed due to COVID-19 related disruption, sorry. I hope to be able to address the issue in a firmware update and I do have some ideas I’d like to try. If you happen to have an AVR ICSP programmer, you can even try an alternate firmware image. Please see here for general instructions and information regarding updating the firmware on the Koryuu.

    Please give me a holler if you’re interested.

    #39511
    megari
    Participant

    As for the Playstation menu in Guld’s case, the shimmering may be normal, while ugly composite artifacts orthogonal the field reversal issue, but this needs more looking into to tell conclusively.

    #39512
    Jarrah White
    Participant

    You’re asking the wrong person, I’m not a computer programmer.

    I don’t have a Koryuu. I have a RetroTINK 2X, though not being able to use the 3X mode on composite and S-video sources is a bit of a bummer. I have considered getting a Koryuu, though that field reversal issue has me concerned. I only use the passthrough mode on interlaced sources.

    #39536
    Guld
    Participant

    I haven’t had time to look at this in quite a while (newborn kiddo ZZzzzzz). But I look forward to trying out a new firmware when one is available. I write C++ code for a living, but don’t have a ICSP programmer and don’t have any friends that do unfortunately. Overall it works great for my needs as is.

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