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EGL Pixbuffer is slow

Ahmed Tolba
Note: This was originally posted on 25th February 2013 at http://forums.arm.com

Hi All,

I'm having a 1k*1k*rgb texture that is rendered using shader and I want to copy the pixels to buffer so that I use Opencv with it. I tried glreadpixels and its very slow, I tried Pixbuffer of Egl, it has the same perforamance its very slow 7FPS. I'm using Mali400 on Exynos4412

Here is the code
  Please view it in pastebin, there is a problem with code posting here

http://pastebin.com/TwrtF0EG
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  • Arm Employee Badge
    Note: This was originally posted on 12th July 2013 at http://forums.arm.com

    Hi Ahmed,

    On GLES3, this can be done with PBO's bound to the GL_PIXEL_PACK_BUFFER target, causing glReadPixels to write to that pbo instead of returning pixel data to the application, which avoids the pipeline stall and flush. The fence is used to signal to the application when this operation has completed and the buffer can be mapped to retrieve the pixel data. There is some sample code in the works but I can't give a date on when this will be available unfortunately. For GLES2, I think for now the only option is pixmaps, but the fence is still supported.

    Hope this helps,
    Chris
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  • Arm Employee Badge
    Note: This was originally posted on 12th July 2013 at http://forums.arm.com

    Hi Ahmed,

    On GLES3, this can be done with PBO's bound to the GL_PIXEL_PACK_BUFFER target, causing glReadPixels to write to that pbo instead of returning pixel data to the application, which avoids the pipeline stall and flush. The fence is used to signal to the application when this operation has completed and the buffer can be mapped to retrieve the pixel data. There is some sample code in the works but I can't give a date on when this will be available unfortunately. For GLES2, I think for now the only option is pixmaps, but the fence is still supported.

    Hope this helps,
    Chris
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