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OpenGL RGB10_A2, Quadro 4000, and DeepColor/10-bit displays Windowed 30-bit OpenGL mode
  • Vote Up3Vote Down thorrablot
    Posts: 5
    I have an OpenGL application (Windows 7) that creates multiple OpenGL RGB10_A2 GCs/viewports (non-full screen application).

    I recently tried the same with a Quadro 4000 to both a Dell U3011 (DeepColor via DP) and NDS Dome E2 (10-bit grayscale via DVI), and although the application acquires the visuals OK, both displays "flash" black for a moment for each RGB10_A2 GC I create (which can be dozens). This is very disruptive, and doesn't occur when using ATI FirePro hardware. I will soon be evaluating a Quadro 2000D on Windows 7, and I suspect it will exhibit the same problem.

    The "flash", I suspect, is the driver and display negotiating some new scanout settings based on the acquisition of each on-screen RGB10_A2 framebuffer. I haven't been able to find any settings in the NVidia control panel that seem relevant to tuning this behavior (e.g. "30-bit desktop mode")

    This is the mode that is described in the NVidia 30-Bit Color Technology for NVIDIA Quadro tech brief, and is documented as suitable for OpenGL windowed applications, however this flashing behavior is clearly not acceptable for a production application.

    Has anyone encountered and resolved this issue?
  • 10 Comments sorted by
  • Vote Up1Vote Down Detlef Roettger
    Posts: 330 Accepted Answer
    The flashing when creating the first 10 bit per channel window is what you suspect. The display driver switches to a different display mode.

    There shouldn't be such flashing after that first one while at least one 10 bpc window is active all the time.
    To clarify, do you create and close these 10 bpc windows or are you opening a dozen windows at the same time?
    For the ealier case, does the flashing go away when you keep one of these 10 bpc windows always active?

    That behavior has been addressed with future drivers under Win7 with the Desktop Windows Manager enabled. I don't know which driver version number will contain that change, yet.
  • Vote Up0Vote Down Detlef Roettger
    Posts: 330
    Could you post the NVIDIA display driver version number(s) on which you've seen this behavior?
  • Vote Up0Vote Down thorrablot
    Posts: 5
    Yes - this happens with both the 276.14 and 285.58 drivers (W7, x32)

    Unrelated - the forum software is marking this as "answered", and telling me to accept/reject the answer. However, I can't find any UI element that will let me do this (I'm using Chrome) - known issue?
  • Vote Up0Vote Down Detlef Roettger
    Posts: 330
    Thanks. Our workstation driver team will try to reproduce the issue.

    The standard forum action is to mark threads as Answered in grey when there is a new comment and when you accept the answer it changes the Answered icon to green. Leave it alone for now. I haven't started a post and don't know where that is, yet.
  • Vote Up0Vote Down thorrablot
    Posts: 5
    I am creating and showing the 10bpc windows sequentially, and they aren't closed until the application shuts down. The windows are losing focus, but they aren't being closed (I'll double check that, as there may some extra window deletion and creation during some layout operations.)

    If I understand your post correctly, you're saying that the current drivers should not be causing flashing after the first 10 bpc window is created and shown - correct? I can make a test app that demonstrates the problem, if that would help isolate the issue.
  • Vote Up0Vote Down Detlef Roettger
    Posts: 330
    Yes, once the display driver has switched to 10 bpc on the first, it shouldn't do that for additional 10 bpc windows.
    A small reproducer project would be highly appreciated. :-)
    Please add the system information text file you can save from the NVIDIA Display Control Panel -> Help -> System Information dialog, that would be helpful to setup a similar reproducer machine here.
  • Vote Up0Vote Down thorrablot
    Posts: 5
    I've returned to this after a few distractions, and found that I can't reproduce it in a simple test application that creates a few viewports - I see the screen switch once for the initial 10bpc window, and then it stays in that mode.

    I believe I've tracked it down to the viewport management (they are inside of a table layout control), and suspect I can avoid the problem by just nailing down a 1x1 window in 10 bpc at application startup.

    Thanks for all the help - much appreciated!
  • Vote Up0Vote Down thorrablot
    Posts: 5
    Final followup - I've confirmed the flashing no longer occurs if I keep a 10bpc window open, which is sufficient for our application. You can close this thread.
  • Vote Up0Vote Down eerriicc
    Posts: 1
    Hi Detlef,

    You mentioned that this first black flash into 10-bit may be fixed in a later driver version and I wondered if this fix is already available and in what version I can find it. Thanks, -eric

    "That behavior has been addressed with future drivers under Win7 with the Desktop Windows Manager enabled. I don't know which driver version number will contain that change, yet."
  • Vote Up0Vote Down Detlef Roettger
    Posts: 330
    Work on that has gone into the imminent Quadro workstation driver release (295.xx or greater). Just keep checking on the NVIDIA driver download site regularly.
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