RPI3B+ WS2801 flickering when black

1st Official Post

    Hello,


    i would like some help.
    My configuration is Raspberry Pi 3 B+ with WS2801 connected to the DI to BCM10 and the CI to the BCM 11.
    The power supply is a 10A one. I tried with an Arduino Nano and with a 74HCT125 level shifter too. The cables are 20 cm long.
    The effects are working great.
    The problem is When the USB capture is enabled.
    If some part of the screen goes dark there is some random flickering which eventually turns off (after 3-4 seconds) if that part remains dark.
    On the live view i cannot see any flickering on the leds.


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    i tried with 4,2 and with 1,1 but there is still flickering if the part of the image goes dark.
    my led layout is 16, 24, 16 and the input position is 44 to start from the lower left edge.
    the last led in the layout seems defect, i changed the layout to 16,24,15 and the input position to 43
    with disabled blackbar detection seems ok, i will play with the threshold


    there is a setting to adjust the sensitivity of the color detection, to not detect the dark colors ?

    Hi, i have the same issue with similar hardware, i belive that in previous versions it has a color treshold, but i can't find it in hyprion.ng, it would be helpfull for this, it's just on the darkest colors (most of the time flicker is green), to prevent that at the moment, i reduced the amount of green by setting green gamma at 1.7, and setting a backgroung treshold at 2, it prevents the led from being totally off, while not getting too bright, and it prevents this type of flicker, but it would be nice to have a red/green/blue treshold as well to adjust the sensitivity of color detection

    Edited once, last by Drakal ().

    Interestingly this is occuring only with a capturing device. With simple effects the leds are going dark.

    Yea that's because analogue grabbers don't support true black. I've moved to a digital grabber for that reason and since then black=black meaning the leds will actually turn off in dark scenes. Don't get the cheap 10 dollar ones from ali, they are really just analogue ones

    https://a.aliexpress.com/_BPNrTn
    This capture card and tweaking the gamma values in h.ng
    Note that the capture card requires usb3 for both the data and the right voltage/amp to work. So it probably doesn't work on a rpi3 but it should on rpi4. I use an ubuntu machine that is running some other stuff like home assistant.

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