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DisplaysShouldNotBeTVs

The HDMI recorder is unfortunately at my home. But I am currently on a business trip. At the end of September, I will return home and will be able to record and send the images.

WhisperingWind that would be useful. I have a Intel arc a770 LE and can experiment for you if you can help me turn the dithering off. I think it's spatial but I still would like it off so there's no chance of it bothering by scrolling or cursor movement. I did order a epiphan dvi2usb 3.0 framegrabber to test output of the cards I have. I do have a dvi2pcie as well but haven't set it up in a PC yet so gonna try the USB one since it was cheap

    jordan I have a Intel arc a770 LE and can experiment for you if you can help me turn the dithering off.

    That would be great!

    I took a closer look at the i915 module code. It appears that dithering is disabled by default and only enabled for 6-bit displays:

    https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/i915/display/intel_display.c#L4777C2-L4782C37

    In other words, my edits theoretically should not have had any effect.

    Hmm, that's strange. Why do my eyes seem to strain a bit less after the edits? It might be related to my hardware setup: Tecno MEGA MINI M1 PC -> Thunderbolt 4 -> Belkin USB-C Video Adapter -> DVI cable -> BenQ GL2450 monitor (6-bit+FRC). I might have accidentally changed some settings elsewhere, which had such an effect, or it could just be the new kernel version. There are many questions.

    I think I need to start by getting a monitor without dithering and see how Linux looks by default on it (maybe I'm not fighting Linux, but my current monitor). And I need to understand how all this works. Otherwise, there will be a lot of magic and unicorns here), which is not good.

    I think I should first learn how to detect dithering in the video card's output signal (I think I can create some kind of detector in Python) and then build further work based on that.

    I will hold off on fully presenting the results until I am completely sure that I have achieved some outcome and it is 100% not a placebo.

    DisplaysShouldNotBeTVs

    Can you please tell me if you have any developments in the field of image processing for detecting dithering? As I understand it, temporal dithering can be detected using the method proposed by aiaf. But what about other types of dithering? Do you possibly have any links to some materials?

      jordan

      Yes, I did.

      The Thunderbolt 4/USB-C 4 output is recognized as a DisplayPort. Therefore, it is possible to set it to 6-bit through xrandr. In this case, the image on the monitor is less straining on the eyes (in the edits I disabled dithering for 6 bits, at least, I hope it works as I expected).

      I removed this lines https://github.com/torvalds/linux/blob/master/drivers/gpu/drm/i915/display/intel_display.c#L4777C2-L4782C37 from the code. I want to return it later and see if there are any changes.

        WhisperingWind interesting. I own a sun vision 32" rlcd that's 6+2frc that I never tried after learning its not true 8 bit. I wonder if it's truly safe as 6bit only in Linux with the arc after driver edit

          jordan

          Does the monitor have a DisplayPort? Otherwise, it might not work, as HDMI (at least in Linux) does not support 6-bit.

          You can try using a video adapter with a DP input, like the one I have, but I'm not sure which one will work in this case. Mine has a USB-C connector, and it won't be suitable for Intel Arc.

          I came across an interesting thing: https://github.com/skawamoto0/ditherig/blob/master/ditherig/database.csv. As I understand it, this is for integrated graphics cards from Intel and AMD. We can play with addresses to disable dithering. This can be done in Linux using the devmem2 program, which can be downloaded from https://github.com/VCTLabs/devmem2. It can be built by running make in the directory with the source code.

          The app can be run like this (you need to substitute the addresses of your own chip, presumably where it says "Disabled"):

          ./devmem2 0x70030 w 0x00000000

          As I understand, the address can be taken from the 8th column, the size is 4 bytes. For simplicity, you can try filling it with zeros (although, of course, one should properly apply a mask from the 10th column).

          I wonder if this will work.

          UPD. In reality, as usual, it turned out to be more complicated: in the 8th column, it's not the actual address but an offset relative to it. The actual address is calculated based on the values of Bar1/Bar2.

            WhisperingWind if i understand you correctly, you want to use a cature card, cature some video frames straight from the display connection and than analyze them in python?

              jordan I use the most mainstream linux distro - Ubuntu with old Lenovo X1 laptop, Intel UHD 620. Also very important, running X11, NOT WAYLAND. Wayland for me introduces some tension. Not as bad as Windows 11, but kind of feels over time. Some suggested to use Y, X, Z in terms of distros. Well I have tried some of them, and I can clearly suggest, if you really about getting work done, do not branch out. It is as messy as it can be, and overall best experience is on mainstream Ubuntu with most features within UI working quite well. Of course it is still buggy, you can not compare it to windows or especially Mac Os, but it is as good as you can get right now. My suggestion for best machine would be lenovo X1, but definitely not brand new. Also, do not expect this to be a permanent solution if you are a macbook user. Macbooks really make things simple, nice to use and just rock solid like calculators.

                Donux Thank you, i had problems with ubuntu in the past(in a good hardware), but i didn't try running X11. I'll try that.

                autobot

                Yes, I want to try doing this. Because a couple of times during experiments, I mistakenly started thinking that my eyes were feeling better, but that wasn't the case.

                  Stock Fedora (40, Wayland, Gnome) improved a previously unusable device for me (running HD 3000, now with i915 driver).

                  The only tweaks of note is that I always set font antialiasing to grayscale and turn off the hinting, as it helps with my astigmatism.

                  Suprisingly on distros that use X that many people have success on here, I fare much worse.

                    I'm using Debian 12 Gnome, I previously use Archlinux but installation is a hassle.

                    Display: ASUS VG258QM
                    Graphics Card: AMD RX6400

                      Donux did you have a negative experience with a newer igpu with same software setup? Also so x11 is default on latest Ubuntu? I haven't used Linux in soooo long but it seems very promising. I am previously a windows user. I just want something that works I don't care for any bells and whistles anymore tbh haha.

                      WhisperingWind that happens to me too sometimes and catches up to me later

                      zlhr is the font hinting a usual setting in settings on Linux distros ? Or is it something that has to be added?

                      eDenon-2 did you alter any settings? DP or HDMI?

                      • zlhr replied to this.
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