Re: Switching between virtual desktops
Luca, The project you describe is much harder than is reasonable for a single person on a tight budget and has some problems you might not recognize. Driving multiple monitors off of one video in a way that is usable isn't as simple as rapidly switching the signal lines. I believe it takes at least one full video frame for any monitor to sync on the signal. Many probably take more. I doubt switching the signal would work acceptably even if you could send one complete frame to one monitor then the next to another monitor then back again. But unless the switching is synchronized with the video signal you will loose a frame each time you switch. I suggest you put something together to rapidly drop and recover the signal to one monitor to verify that the whole idea will work with a specific monitor. I am very sceptical. Switching the signal without all kinds of signal bounce (as with a button, switch or relay) isn't trivial, there might be an IC for the task though. You probably only need to switch the horiz and vertical sync signals for VGA. The monitor will defiantly "notice" a lost signal. The LCD controller needs to know where in the data stream that the current pixel is when it is delivered to know what pixel on the screen to set. I don't think most LCDs buffer the frame, there is no need. What could work is using an FPGA like the Xilinx Spartan III (I think this has enough power) on a custom circuit board feed by a dual-link dvi (more expensive card) with single link DVI outputs. But you will have to develop Verilog or VHDL code to decode part of the DVI signal produce an appropriate clock for each output, buffer each video line and shift it out to each output appropriately. This is a good month project to prototype for someone who knows what they are doing and has all the right equipment. The Matrox Graphics eXpansion Modules are basically this, but the price tag is over $300. I have considered developing such devices but I would never sell a 1 to 6 head DVI line buffering splitter for less than $150 (assuming I could sell over 10,000 units), nobody else will either. You could only drive 4 1280x1...@60hz panels from one dual link DVI port. You either have to reduce the res/refresh rate or have a device that buffers the whole frame, and that will be more expensive. Even with this the current Xserver can't be setup to have multiple independent displays on one monitor. Maybe this will change one day. A video splitter that actually works well is a significant design project for one person and easily justify 6 credit hours of design class credits for an electrical engineer major. As the Matrox product proves it can be done. Packing a system with a bunch of PCI video cards really is your best bet. I would look harder for those cards. Someone probably has a bunch laying around they would be happy to sell for little or nothing. Check around campus or other companies, or computer parts auctions. I have 2 or 3 on a shelf somewhere. But the legacy VGA arbiter problem might make the whole thing not work http://www.x.org/wiki/VgaArbiter LCD's aren't exactly cheap. If you where building this new, the total LCD cost would probably be more than the system cost for a 6 display system. Probably total new cost of about $1200 for 6 displays. Can you procure the whole thing new? I expect you could find a single vendor that will sell the whole thing. ___ xorg mailing list xorg@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/xorg
Re: Switching between virtual desktops
Luca, X windows systems have a display for each desktop environment (KDE, Gnome). All X windows applications look for a display server usually specified by the DISPLAY environment variable then connect to that server via local mechanism or a network socket. Go to a terminal and type "echo $DISPLAY" you will probably get ":0.0" that number specifies what local display to use. If your system is setup for multiple simultaneous X logins (newer distros) each login will have a different xserver and display, the environment variable is how processes launched in each environment know what xserver to connect to. Only one xserver process can use a video card at one time, though they can hand off control from one server to another and the text console typically using the Ctrl+Alt+Fx keys. Until the recent xrandr 1.2 implementation, if an xserver was setup to use two monitors it would create two displays one for each monitor unless the Xinerama option was on. In this case a different desktop environment could be run on each display with a common keyboard and mouse which I think is what you are asking. If you have two separate video cards, it is possible (though there can be issues) to run a different xserver instance for each card with an independent mouse and keyboard. So one computer with two sets of video, keyboard and mouse could act like two different computers. This can also be done with one dual headed video card using Xephyr, but lacks some features (3D) and will be a little slower. Check out http://www.x.org/wiki/Development/Documentation/Multiseat Why do you need to switch between virtual desktops rapidly from a script? Are you sure this is the right solution to your problem? Quinn ___ xorg mailing list xorg@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/xorg
Re: No MergedXinerama for xrandr
On Sunday 31 May 2009 8:02:31 pm Alex Deucher wrote: > On Sun, May 31, 2009 at 6:49 PM, Quinn Harris wrote: > > Before many video drivers changed from MergedFB to xrandr 1.2 for a dual > > head video card they had an option like "NoMergedXinerama" > > for the Radeon driver that would make the two screens appear as one to > > the window manager. Does a similar option exist somewhere now > > with xrandr 1.3? Is there a way to completely disable a window managers > > awareness of multiple screens? > > > > I have a Viewsonic VP2290b that needs to be driven by two DVI ports to > > run at full resolution at a usable refresh rate (24hz). But I > > don't want the desktop (KDE 4.2) to treat the single monitor like two in > > any way. > > It's all handled in the common xserver code now for xrandr 1.2 rather > than in the drivers. Your best bet is probably to turn off xinerama > support in your window manager. > > Alex I also noticed mplayer and Xine also recognized multiple monitors. The Firefox "awesome bar" adjusts where it shows based on the monitor edge that doesn't actually exist in my configuration. I wasn't able to find an option in KDE 4.2 to ignore Xinerama or the like, but haven't looked hard. Something at the xserver level would be nice. A global option or better yet a way to instruct xrandr to treat two or more specified screens as one to all X software. This is basically another feature regression with xrandr and should probably be considered to be resolved in a future revision. Quinn Harris ___ xorg mailing list xorg@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/xorg
No MergedXinerama for xrandr
Before many video drivers changed from MergedFB to xrandr 1.2 for a dual head
video card they had an option like "NoMergedXinerama"
for the Radeon driver that would make the two screens appear as one to the
window manager. Does a similar option exist somewhere now
with xrandr 1.3? Is there a way to completely disable a window managers
awareness of multiple screens?
I have a Viewsonic VP2290b that needs to be driven by two DVI ports to run at
full resolution at a usable refresh rate (24hz). But I
don't want the desktop (KDE 4.2) to treat the single monitor like two in any
way.
I was using the proprietary nVidia drivers with the "NoTwinViewXineramaInfo"
option for a similar effect.
My current xorg.conf file:
Section "Monitor"
Identifier "Monitor0"
VendorName "ViewSonic"
ModelName "VP2290b"
Modeline "1920x2400_24" 119.40 1920 1928 1980 2044 2400 2402
2405 2435
ModeLine "1920x2400_30" 149.3 1920 1928 1980 2044 2400 2402 2405
2435
EndSection
Section "Monitor"
Identifier "Monitor1"
VendorName "ViewSonic"
ModelName "VP2290b"
Modeline "1920x2400_24" 119.40 1920 1928 1980 2044 2400 2402
2405 2435
ModeLine "1920x2400_30" 149.3 1920 1928 1980 2044 2400 2402 2405
2435
Option "LeftOf" "Monitor0"
EndSection
Section "Device"
Identifier "Device0"
Driver "ati"
Option "AccelMethod" "EXA"
Option "AccelDFS""true"
Option "monitor-DVI-0" "Monitor0"
Option "monitor-DVI-1" "Monitor1"
EndSection
Section "Screen"
Identifier "Screen0"
Device "Device0"
Monitor"Monitor0"
DefaultDepth24
SubSection "Display"
Virtual3840 2400
Depth 24
Modes "1920x2400_24"
EndSubSection
EndSection
Section "ServerLayout"
Identifier "Layout0"
Screen 0 "Screen0" 0 0
EndSection
Section "ServerFlags"
Option "DontZap" "False"
EndSection
---
Quinn Harris
qu...@qutek.net
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