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Thread: Screen lines at 75 hz

  1. #21
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    Re: Screen lines at 75 hz

    I think the native is 1152x864 but 75Hz refresh is greater than max pixel clk in EDID..

    Code:
    $xrandr --newmode "1152x864_60.00"   81.75  1152 1216 1336 1520  864 867 871 897 -hsync +vsync
    $xrandr --addmode HDMI-0 "1152x864_60.00"
    $xrandr --output HDMI-0 --mode "1152x864_60.00"
    $xrandr --output HDMI-0 --scale 1x1
    $xrandr --fbmm 475x267
    Last edited by BicyclerBoy; January 28th, 2013 at 09:00 AM.

  2. #22
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    Re: Screen lines at 75 hz

    trash unity no good for nothing stupid make it better cant find nothing eny more
    worse then windows

  3. #23
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    Smile Re: Screen lines at 75 hz

    BicyclerBoy: Am I supposed to add your code at the end of the file, or in place of something else? And is it safe (meaning, is there a risk for my computer to break down if it's not a resolution that's supported)? I've never seen a choice for such resolution, even on Windows.

    heli1: Actually, I would be quite satisfied with it were it not for this problem... I've had my share of problems over the year, but in recent years, Ubuntu seemed to work perfectly for me, with Unity. So if I can solve the problem without resorting to something other than Unity, I'd prefer that!

  4. #24
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    Re: Screen lines at 75 hz

    Just enter those cmds in terminal or stick them in a text file/script & run it from terminal..

    I don't believe you can damage any modern monitor (inc CRT).

    The 75Hz rates of 1280x1024 & 1152x864 are excluded from "video mode pool" because the pixel clock is greater than max in EDID.
    The 60Hz refresh makes more sense.
    Alternatively it is possible to force the max pixel clock freq test to be ignored, I just don't know the ati/radeon keywords..

    If you want to try 1280x768 60p:
    Code:
    $xrandr --newmode "1280x768R"   68.00  1280 1328 1360 1440  768 771 781 790 +hsync -vsync
    or
    $xrandr --newmode "1280x768_60.00"   79.50  1280 1344 1472 1664  768 771 781 798 -hsync +vsync
    you have to craft the remaining cmds to use the "mode label".

    The problem with Unity was forcing it on users with no obvious/easy way to get to gnome-fallback or similar.
    There should have been a Canonical version of "cinnamon" desktop.
    Last edited by BicyclerBoy; January 29th, 2013 at 10:31 PM.

  5. #25
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    Smile Re: Screen lines at 75 hz

    Great! I think the problem is nearly solved.

    I entered those commands (1152x864_60.00 just didn't work, resolution not supported):

    xrandr --newmode "1280x768_60.00" 79.50 1280 1344 1472 1664 768 771 781 798 -hsync +vsync
    xrandr --addmode HDMI-0 "1280x768_60.00"
    xrandr --output HDMI-0 --mode "1280x768_60.00"
    And it worked!

    However, when I restart the computer, it goes back to the 1024x768 resolution, even after I deleted the command line in Startup Applications.

    So I decided to put each one of those three lines of code into a different startup application (or is there a way to maybe put all three into one "application?"), but it doesn't seem to do anything: it still goes to 1024x768.

    Would you have any idea of how to set those three marvelous lines of code so that I don't have to type them every time I start the computer?

  6. #26
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    Re: Screen lines at 75 hz

    I would try placing them in /etc/rc.local
    or into a script with the script (full path) invoked/run from /etc/rc.local

    Your script needs a shebang (#!/bin/sh) & execute bit set..

    It is possible to create/use /etc/X11/xorg.conf but the syntax is a little different & not as flexible.

    Try the reduced VB 60Hz timing as well. Should work on any DFP.
    FYI.
    The timings were generated from:
    $cvt -r 1280 768 60

  7. #27
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    Smile Re: Screen lines at 75 hz

    Hi BicyclerBoy,

    I spent a few hours trying what you said, but I'm afraid much of what you wrote is way too technical for me. I don't know whether to add those lines before or after the "exit 0" of the rc.local, I don't understand what you mean by "Your script needs a shebang (#!/bin/sh) & execute bit set.." and I don't know how to "Try the reduced VB 60Hz timing as well."

    If this is too much work to explain, please disregard: you've helped me so much already, and the screen display now works fine if I enter those three commands each time I start the computer. Trying to do that automatically is just a minor issue.

    Thank you,

    FlyingMandarine

  8. #28
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    Re: Screen lines at 75 hz

    Put the cmds in the rc.local file just before "exit 0"..

    The "exit 0" sets the exit value to 0 (no error) if the script completes/gets to end.

    The reduced (vertical blank) timings are the default 60Hz video modes over HDMI/DVI.

    This cmd generates reduced blanking timings:
    $cvt -r 1280 768 60

    just try the reduced video modeline in place of the other "1280x768_60.00".
    You need to change all 3 commands..
    Last edited by BicyclerBoy; February 4th, 2013 at 08:22 PM.

  9. #29
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    Smile Re: Screen lines at 75 hz

    Hi BicyclerBoy, sorry for the late answer,

    I put the commands in /etc/rc.local; it looks like this:

    # By default this script does nothing.

    xrandr --newmode "cvt -r 1280 768 60" 79.50 1280 1344 1472 1664 768 771 781 798 -hsync +vsync
    xrandr --addmode HDMI-0 "cvt -r 1280 768 60"
    xrandr --output HDMI-0 --mode "cvt -r 1280 768 60"

    exit 0
    But it still didn't do anything -- although writing them separately one after another in the Terminal works very well.

  10. #30
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    Re: Screen lines at 75 hz

    I should try out cmds before suggesting them..

    I guess the above failed because the rc.local file is run before the X server is loaded..

    Short of using an xorg.conf file (to be avoided)...
    a script in ~/.xinitrc/ (private to user; "~" means home path)

    The suggested system wide Xinit script location seems to have vanished..
    Last edited by BicyclerBoy; February 9th, 2013 at 09:44 AM.

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