[mythtv-users] Modeline works in Powerstrip/Windows, but not in Xorg/Linux

James Buckley xanium4332 at googlemail.com
Sat Dec 23 12:20:50 UTC 2006

Hi all,

Basically, I have a problem...
I have my MythTV box connected to my TV using a DVI link (striaght
DVI->DVI, no HDMI, converters or anything like that). My TV has two
modes for the DVI connection, DVI-PC and DVI-DTV (It's an LG 37LP1D).
When switched to DVI-PC mode, I can output almost any resolution I
like and get a picture (it even outputs the correct E-DID info to let
me get 1:1 pixel mapping, and no overscan). However, this ability
comes at a price.

It seems that the TV drops frames, as watching video is impossible,
and dragging windows clearly shows a terrible frame rate. I know this
is a problem with the TV (as I'll explain later). Obviously I
want/need to use the DVI-DTV mode on the TV, however that dragged in
the typical problem of getting the correct modeline. The TV outputs
the same E-DID info as when switched to the DVI-TV mode, but none of
the generated resolutions work. I guessed that when in the DVI-DTV
mode, my TV expects stricter modelines, but won't drop any frames.

My guess was correct. I loaded up XP on my box, installed powerstrip,
and using one of it's default/inbuilt resolutions/modelines (the
1280x720 (DTV)) I actually managed to get a picture when in the DTV of
my TV. You can clearly see a difference between the two modes. In PC
mode, no overscan, low framerate. In DTV mode, little overscan, high
framerate (things are actually smooth, and video's watchable).

OK, all I needed to do is cut and paste the modeline from powerstrip
to Xorg. No problem, so I generated the modeline from Powerstrip
(using the copy to clipboard thing), and pasted it into my xorg.conf.
Now here's the problem: no picture (at least not in DTV mode). I've
checked all the logs, and the modeline is confirmed, correct, accepted
and applied, but I don't get any picture.

Now, here's my question, does anybody know why this is? I've been
working on this project since Easter, and this is the only problem I
have left (but quite a severe one). I'd really like to have a pure
digital connection, as the component (yes, component) out from my
motherboard (an MSI K8NGM2-FID), isn't very good.

If anyone has an idea as to why all this is, or has any info at all
regarding the subject/problem, pleaassseee speak up.

Thanks in advance, James

P.S. I've posted my xorg.conf, just in case somebody notices anything
wrong / problematic. Oh, and I'm running on Gentoo, using the nvidia
1.0.9631 binary drivers.

Section "ServerLayout"
        Identifier     "X.org"
        Screen      0  "Screen" 0 0
        InputDevice    "Mouse" "CorePointer"
        InputDevice    "Keyboard" "CoreKeyboard"

Section "Files"
        RgbPath      "/usr/share/X11/rgb"
        ModulePath   "/usr/lib/xorg/modules"
        FontPath     "/usr/share/fonts/misc/"
        FontPath     "/usr/share/fonts/TTF/"
        FontPath     "/usr/share/fonts/OTF"
        FontPath     "/usr/share/fonts/Type1/"
        FontPath     "/usr/share/fonts/CID/"
        FontPath     "/usr/share/fonts/100dpi/"
        FontPath     "/usr/share/fonts/75dpi/"

Section "Module"
        Load  "extmod"
        Load  "dbe"
        Load  "record"
        Load  "xtrap"
        #Load  "dri"
        Load  "glx"
        Load  "freetype"
        Load  "type1"

Section "InputDevice"
        Identifier  "Keyboard"
        Driver      "kbd"

Section "InputDevice"
        Identifier  "Mouse"
        Driver      "mouse"
        Option      "Protocol" "auto"
        Option      "Device" "/dev/input/mice"
        Option      "ZAxisMapping" "4 5 6 7"

Section "Monitor"
        Identifier   "TV"
        VendorName   "LG"
        ModelName    "37LP1D"
        Option       "ModeValidation" "NoMaxSizeCheck,
NoHorizSyncCheck, NoVertR

        Option       "DPMS"
        VertRefresh  56-75
        HorizSync    31-70
        DisplaySize  325 182

        Modeline     "720p" 77.50 1280 1600 1648 1648 720 720 725 748
+hsync +vsync

Section "Device"
        Identifier  "GFX Card"
        Driver      "nvidia"
        VendorName  "nVidia Corporation"
        BoardName   "C51PV [GeForce 6150]"
        BusID       "PCI:0:5:0"
        VideoRam    65536
        Option      "NoLogo" "true"
        Option      "ConnectedMonitor" "DFP"

Section "Screen"
        Identifier "Screen"
        Device     "GFX Card"
        Monitor    "TV"
        DefaultDepth 24
        SubSection "Display"
                Viewport   0 0
                Depth     24
                Modes     "720p"

Section "dri"
        Mode 0666

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