Hi Holger,

On Mon, Aug 8, 2011 at 11:32 AM, Holger Freyther <[email protected]> wrote:

>  <gunnar.sletta <at> nokia.com> writes:
>
>
> > The scene graph adaptation layer has support for plugging in decoding
> straight
> to an OpenGL texture. This
> > is similar API to the lighthouse API, in that it is backend API which is
> implemented pr platform/device and
> > which may change over time. The logic is in
> QSGContext::canDecodeImageToTexture() and
> QSGContext::canDecodeImageToTexture().
> >
> > We have no plans to do any more work for DirectFB.
>
> Don't worry, I will not ask you to do the work.
>
> So here is the quiz. From what I understand there is HW where the GPU
> and the VideoDecoder share the same DDR RAM, and the VideoDecoder
> will decode frames to given areas in that RAM.
>
> Would you know how to access this decoded piece of memory as texture
> with OpenGL. Assumingly you only know the physical address and size
> in that memory?
>

Just FYI, there's activity going on in Linaro at the moment for this very
use-case (check out the mailing list set-up for the work):

https://wiki.linaro.org/OfficeofCTO/MemoryManagement

In short - Linaro are developing an in-kernel framework for sharing buffers
between different hardware devices (a video decoder and a GPU say). Once
that's in place, there's plans to hack on various userspace projects to add
support (like GStreamer & DRI2). There's also a plan to define an EGL
extension which allows an EGLImage to be created from a inter-device buffer.
Once you have an EGLImage, you can bind that to a texture (though you might
need to use OES_EGL_image_external for that if the EGLImage is in YUV
format).


I assume once the kernel & userspace pieces are put in place, it should be
fairly easy to add support for them into Qt?



Cheers,

Tom



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