SNES + OSSC Noise in image

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  • #40227
    Maka8295
    Participant

    Hello! Does anyone know what could cause this problem? (https://imgur.com/a/g206uYv)
    it’s mainly visible in the black areas above and below, but it sometimes can encroach into the actual game screen during certain screens. My console is a modded 1chip03 with an RGB bypass. The problem also doesn’t seem to be visible at all over AV. Its also visible across multiple TVs.

    It also seems to be visible on my PS2 with the OSSC, albeit much much fainter. It may be unrelated, as it seems to behave slightly differently.

    Could it be a power issue? Cable issue?

    Any help at all would be much appreciated!! 🙂

    • This topic was modified 5 days, 20 hours ago by Maka8295.
    #40229
    Zacabeb
    Participant

    Something is triggering the ALC (automatic level control) in the video ADC to raise the black level incorrectly.

    First try reducing the pre-ADC gain in the Video in proc menu by a step or two and see if that helps.

    If not, try reducing the ALC V filter setting in the Video in proc menu. This will make the ALC respond faster and possibly fix the varying black level, but might also cause flicker if reduced too much.

    Note that adaptive backlight in the display can interact with this.

    • This reply was modified 5 days, 20 hours ago by Zacabeb.
    #40232
    Maka8295
    Participant

    Thank you very much for the response! I’ll try this and report back!

    #40233
    Maka8295
    Participant

    I’ve tried reducing the pre-ADC gain and it doesn’t fix the problem unfortunately. Forgive me if i’m missing something simple but I can’t find the ALC V filter settings anywhere. I found the setting on the junkerhq site but It doesn’t seem to be on my OSSC. I’m pretty sure i’m on the latest firmware as I updated it a few months ago.

    • This reply was modified 5 days, 17 hours ago by Maka8295.
    #40234
    Zacabeb
    Participant

    The lastest firmware at the time of writing is 0.85, and that’s the firmware in which the ALC settings were added.

    #40236
    Maka8295
    Participant

    Oops! I’ll update again and get back to you! Thank you very much 🙂

    #40247
    Maka8295
    Participant

    I can get rid of 90% of the problem by setting the ALC V filter all the way down to 1. There’s still a little bit left at the part closest to the game image on the bottom. Its a flickery line that goes from the center of the screen to the right and its the first row right under the game window, it looks to be 1 pixel tall. I don’t notice any flicker in the game itself thankfully!

    Thank you so much for the help! 🙂 Do you have any inkling as to what may have caused the black level to be increased? Could it be indicative of some kind of problem? For what’s its worth, the issue appears as a red noise on my PS2, and was also red on my SNES to begin with, but after I redid my RGB bypass it changed from red to the white I posted in those pictures.

    • This reply was modified 5 days, 5 hours ago by Maka8295.
    • This reply was modified 5 days, 5 hours ago by Maka8295.
    • This reply was modified 5 days, 5 hours ago by Maka8295.
    #40257
    Zacabeb
    Participant

    You’re welcome. 🙂

    Alas, I don’t know enough about electronics to have a definitive answer. I’m going to have to let someone else answer that.

    I had the same problem myself with some PS/PS2 games using an official Sony component cable from the PS2. In my case it sufficed to reduce the ALC V filter to 16 lines.

    • This reply was modified 5 days ago by Zacabeb.
    #40259
    Maka8295
    Participant

    Hopefully its just my cable as well thats causing it rather than the SFC or OSSC itself having problems. I’m getting another 1chip in the mail soon so I’ll mod that and see if that narrows down what’s causing it! 🙂

    Thanks again!

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