External monitor resolution problem

[Howard]

I use a Dell Inspiron mini10v netbook with LXDE (fully updated).

I have just bought a Samsung T27A300 small-TV/large-monitor.  The problem is that the Samsung only has HDMI inputs (+RCA type audio-video or composite) while the external monitor output on the Dell is 15 pin VGA.  (It came with a HDMI to DVIa cable, but that isn't much use.)
I've bought a VGA to HDMI converter box and that works, but there is a catch 22 situation.  I cannot set the resolution of the external monitor using the PCC "in absentia" - it has to be plugged in.  The converter box determines its resolution from what it is plugged in to, and picks up the 1024x600 from the Dell.  Then the PCC says "this is a 1024x600 monitor" and won't let me go higher.

I tried in windows XP and was able to set the second screen at 1080p settings - but what would I want to run XP for when I've got LXDE .   
 
The main reason I want to hook up the Samsung is that we have a number of Zone 2 DVDs from the UK and would like to watch them on the larger screen.  (Can't do that from XP without purchasing(!!!) some extra add ons for the WM player - and why do that when it runs well with free Linux software.)

So how can I set the external monitor signal to 1080p dimensions before I plug it in?  The 1024x600 isn't bad, but it would be nice to get the maximum sharpness.

[Just17]

What happens if you turn on the TV and the converter box without being connected to the PC .....  and then connect to the PC ......  or cold boot (not reboot) the PC with the connection made?

It just might cause something different to happen .......   only guessing ......

[Howard]

I think I've already tried all possible combinations!

[Yankee]

I think I've already tried all possible combinations!

There is a way to do it with xrandr.   Can't find the exact thread.

But when using xrandr selecting option "0" will give the highest
resolution and so forth.   Syntax has to be exact.   The highest
resolution is "0".   Invoke the command using that.   You could
write a short script to use when using the bigger monitor.
Sorry can't find the exact syntax right now, but a clue is a clue.

[Howard]

Thanks, I thought this thread had become dead! 

I had a look at xrandr via man xrandr and xrandr -help and it looks as though it should do the job.  but I'm not too experienced and while I'm happy to experiment  I'm reluctant to do so in this case in case I screw up my display and it isn't cured on a reboot.  In the meantime here's what I get from a plain xrandr:

#xrandr
Screen 0: minimum 320 x 200, current 1024 x 600, maximum 4096 x 4096
VGA1 disconnected (normal left inverted right x axis y axis)
LVDS1 connected 1024x600+0+0 (normal left inverted right x axis y axis) 223mm x 125mm
   1024x600       60.0*+   60.0 
   800x600        60.3     56.2 
   640x480        59.9 

So it looks as thought I can set the VGA independently of the normal display - if I can work out the syntax.

I presume this is a root thing.

[agmg]

Maybe my similar experience with xrandr can help you sort it out:

http://www.pclinuxos.com/forum/index.php/topic,103010.0.html

I think you must have the tv connected on boot so you can configure it properly with xrandr...

[Howard]

Thanks very much.  That might work, but my situation is a bit different as I'm going from netbook to TV via a VGA-HDMI converter which looks back at the computer for its resolution settings.  Still it's worth experimenting with when I've an hour to spare!

[agmg]

You do that and share your results

[Howard]

Just tried that.  I've got the xrandr syntax sorted out thanks to your other posting. but even with the VGAtoHDMI adaptor and TV plugged in and switched on I only get the internal options of 1024x600, 800x600, and 640x480.  As I said it's a catch 22 situation. 

The VGA adaptor will recognise up to 1920x1080, but PCLOS won't allow me to set it.  XP will, so it's not a hardware limitation.

[agmg]

What resolutions gives you the command "xrandr -q" in console with the external monitor connected?

[Howard]

What resolutions gives you the command "xrandr -q" in console with the external monitor connected?

I get exactly the same for both screens i.e:

1024x600       60.0*+   60.0
   800x600        60.3     56.2
   640x480        59.9


But I have got a little further myself, I found this posting elsewhere which suggests a way to add additional modes using --newmode:

http://dound.com/2010/01/overcoming-linux-screen-resolution-limitations/

I tried his figures and the mode appeared, but I'm puzzled, as he says his monitor is 1920x1080, but actually uses 1920x1200 in his mode - and I have no idea what all those other numbers mean.

Using his values it appears to work, but I got an "invalid mode" message on my TV screen not surprisingly.  Still it looks like a step in the right direction - all I need to do is to find the right values for all those parameters!

Just going to settle down and watch a UK DVD at 1024x600 scaled up, it isn't too bad!

[agmg]

Did you try setting your TV to 1920X1080 with the "--newmode" parameter?
The other numbers following the resolution, define the monitor's modeline:

http://en.wikipedia.org/wiki/XFree86_Modeline

This guide you found is rather old (since 2010) and modelines are no longer defined on xorg.conf.
What does YOUR xorg.conf look like? Give the command "kwrite /etc/X11/xorg.conf" as root (su) and paste its contents here to let me have a look.

It is strange though that xrandr doesn't report resolutions up to 1920x1080 for the monitor. Do have the monitor connected before you turn on your computer and boot to PCLinuxOS?

I remember having the same issue with the old graphics card of my kids' PC, in which I had to force this resolution each time the system booted. But it worked. Of course this was with another distro and that PC now has a decent ATI card, but it just came up to me so I mention it here.

[Howard]

Thanks for that suggestion I'll try it tomorrow.

I don't think you've quite grasped my set-up though.  The computer has an analogue (VGA) output which goes into an analogue to digital converter and comes out digital - HDMI.  I don't think that EDID is going to get through that and pick up the TV's modes, just whatever the VGA end is set at, and that sets itself by looking back at what the computer is putting out.

However I think that forcing a high resolution mode via --newmode should work if I can get the right values - maybe the ones I tried will work for 1920x1080 as well as 1920x1200 - I'll try it.

Here's the xorg.conf file (as found in leafpad!)

Code: [Select]

Section "ServerFlags"
    Option "DontZap" "False" # disable <Ctrl><Alt><BS> (server abort)
    #DontZoom # disable <Ctrl><Alt><KP_+>/<KP_-> (resolution switching)
    AllowMouseOpenFail # allows the server to start up even if the mouse does not work
EndSection

Section "Module"
    Load "dbe" # Double-Buffering Extension
    Load "v4l" # Video for Linux
    Load "extmod"
    Load "glx" # 3D layer
    Load "dri" # direct rendering
EndSection

Section "Monitor"
    Identifier "monitor1"
    VendorName "Generic"
    ModelName "Flat Panel 1024x600"
    HorizSync 28.8-90
    VertRefresh 60
    
    # TV fullscreen mode or DVD fullscreen output.
    # 768x576 @ 79 Hz, 50 kHz hsync
    ModeLine "768x576"     50.00  768  832  846 1000   576  590  595  630
    
    # 768x576 @ 100 Hz, 61.6 kHz hsync
    ModeLine "768x576"     63.07  768  800  960 1024   576  578  590  616
    
    # modeline generated by gtf(1) [handled by XFdrake]
    ModeLine "1024x600_120"  107.41  1024 1096 1208 1392  600 601 604 643  -HSync +Vsync
    
    # modeline generated by gtf(1) [handled by XFdrake]
    ModeLine "1024x600_100"  87.51  1024 1088 1200 1376  600 601 604 636  -HSync +Vsync
    
    # modeline generated by gtf(1) [handled by XFdrake]
    ModeLine "1024x600_85"  72.83  1024 1080 1192 1360  600 601 604 630  -HSync +Vsync
    
    # modeline generated by gtf(1) [handled by XFdrake]
    ModeLine "1024x600_75"  63.20  1024 1080 1184 1344  600 601 604 627  -HSync +Vsync
    
    # modeline generated by gtf(1) [handled by XFdrake]
    ModeLine "1024x600_60"  48.96  1024 1064 1168 1312  600 601 604 622  -HSync +Vsync
    
    # modeline generated by gtf(1) [handled by XFdrake]
    ModeLine "1024x600_50"  39.55  1024 1048 1152 1280  600 601 604 618  -HSync +Vsync
EndSection

Section "Device"
    Identifier "device1"
    VendorName "Intel Corporation"
    BoardName "Intel 810 and later"
    Driver "intel"
    Option "DPMS"
EndSection

Section "Screen"
    Identifier "screen1"
    Device "device1"
    Monitor "monitor1"
    DefaultColorDepth 24
    
    Subsection "Display"
        Depth 8
        Modes "1024x600"
    EndSubsection
    
    Subsection "Display"
        Depth 15
        Modes "1024x600"
    EndSubsection
    
    Subsection "Display"
        Depth 16
        Modes "1024x600"
    EndSubsection
    
    Subsection "Display"
        Depth 24
        Modes "1024x600"
    EndSubsection
EndSection

Section "ServerLayout"
    Identifier "layout1"
    Screen "screen1"
EndSection

[agmg]

I found the guide I had used to solve the resolution problem on my kids' PC with the old Intel card:

http://superuser.com/questions/311378/how-to-get-a-higher-resolution-on-ubuntu-11-04-using-an-intel-chipset

And here is more info about the "cvt" command:

http://linux.die.net/man/1/cvt

http://www.4ahomes.com/wp/2010/01/01/controlling-multiple-screens-with-xrandr-cvt-and-xvidtune/

You can use "cvt" for the resolution of 1920X1080 to get the TV's mode lines...

Hope this helps a little more...

[Howard]

Thanks agmg, the those references have more or less solved it.  The first one was most useful.  There are still a couple of wrinkles to sort out, which may be hardware limitations, but the principle is established.

1. It changed the screen size for both the external VGA and the internal DVI screen, so my netbook screen was only showing the top left hand corner when the external TV was "full" screen.

2. "Full" screen on the external monitor wasn't the full width of the TV, there was about an inch of blackness each side of the screen, and the display was horizontally squished slightly, making faces a bit thin!  (This is a bit odd as when the TV initially picked up the signal it said it was 1920x1080.)

3. The adaptor/TV didn't pick up 1920x1080 if I set that first (no signal), but if I started with the native 1024x600 and then typed in

Code: [Select]

xrandr --output VGA1 --mode 1920x1080 it switched OK.  (I must go back over my commands to see if there was a typo somewhere.)