Vertical Sync and Tearing Effect - X

This is a discussion on Vertical Sync and Tearing Effect - X ; Hi, I have an application that directly draws data from the camera driver to the VRAM using DGA Extension. However, when the movement is very fast, the image drawn shows a "tearing effect" because the display is not in sync ...

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Thread: Vertical Sync and Tearing Effect

  1. Vertical Sync and Tearing Effect

    Hi,

    I have an application that directly draws data from the camera driver
    to the VRAM using DGA Extension. However, when the movement is very
    fast, the image drawn shows a "tearing effect" because the display is
    not in sync with the vertical refresh rate.

    I have 16 MB of VRAM and each image is only 2MB. I tried using
    XF86DGASetViewPort and XF86DGAViewPortChanged so that I could write in
    a portion of RAM that is not mapped to the display (double buffering).
    However I found out that the maximum x and y positions possible with
    the XDGASetViewport are both 0s (I used XDGAQueryModes for this).

    My question is it possible to change the maximum x and y positions so
    that I could use double buffering technique? If not, what are my
    alternatives?

    Thanks,
    Ina

  2. Re: Vertical Sync and Tearing Effect

    ina miranda wrote:
    > Hi,
    >
    > I have an application that directly draws data from the camera driver
    > to the VRAM using DGA Extension. However, when the movement is very
    > fast, the image drawn shows a "tearing effect" because the display is
    > not in sync with the vertical refresh rate.
    >
    > I have 16 MB of VRAM and each image is only 2MB. I tried using
    > XF86DGASetViewPort and XF86DGAViewPortChanged so that I could write in
    > a portion of RAM that is not mapped to the display (double buffering).
    > However I found out that the maximum x and y positions possible with
    > the XDGASetViewport are both 0s (I used XDGAQueryModes for this).
    >
    > My question is it possible to change the maximum x and y positions so
    > that I could use double buffering technique? If not, what are my
    > alternatives?


    You have ensured that you've got free VRAM left over after the screen
    takes up its amount?

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