[Interest] I.MX6 and QT5

[Thomas Senyk]

On Thu, January 17, 2013 13:52:06 Mandeep Sandhu wrote:
> On Wed, Jan 16, 2013 at 4:22 AM, Eric Nelson
> 
> <eric.nelson at boundarydevices.com> wrote:
> > On 01/15/2013 03:43 PM, qtnext wrote:
> >> thanks for the info ... I hopes that with I.MX6 it's possible to decode
> >> HD video in hardware and for example remap to an opengl texture or
> >> quick2 item , but I have checked on freescale website and I am not sure
> >> if accelerated decoding is not only for overlay display...
> >> 
> >  > <snip>
> > 
> > Possible? yes.
> > 
> > Easy? Maybe for someone with a very precise set of knowledge...
> > 
> > The VPU decoder natively supports YUV output, which, as you mention
> > can be directly fed to a hardware overlay layer.
> > 
> > The Vivante GPU also supports a variety of YUV planes though, so
> > there's a possibility that a memory buffer known to the GPU can
> > be used as the 'sink' for a gstreamer element and the GPU could
> > work with or convert it as necessary.
> 
> We're also using a media SoC with Vivante GPU and Qt 4.8 (on
> DirectFB). We have a media player application (2D gfx only) that uses
> GStreamer with Fluendo gst elements for audio/video decoder and sinks.
> Both media decoding and 2D gfx are h/w accelerated. The SoC offers 4
> h/w planes with
> 
> We merge the o/p of Qt and Gstreamer on the various h/w planes made
> available by the SoC (there are 4 of them). The z-order is such that
> the OSD plane (used by Qt) comes on top of video plane. The video is
> visible by making the required area on the OSD plane transparent.
> 
> I don't have much exp with openGL, but wouldn't that work for merging
> opengl surface with the decoded video o/p as well? Why would you want
> to give the GPU buffer to the Gstreamer sink?
> 
> Though I understand that any effects applied on the OSD layer (i.e in
> Qt) would not work on the video as that would be a different plane.

They concept is to use the GPU-buffer (maybe a FBO) as a texture
(that's how it's done on the desktop and other embedded HW)

That why you can use the video in the same matter as any other item in your 
SceneGraph (e.g. transform, translate, shadereffect, mapping on 3D-items,....)

... so it's about features and flexibility.

If you want a straight, simple, pixel- and color-perfect video-player... the 
HW-plane sounds like the better choice.
If you want to apply shadereffects to it 
(http://www.youtube.com/watch?v=SMRln8FJvKc) you have to have a video-texture.


Greets
Thomas


> 
> -mandeep
> 
> > Just how that magic would happen, and what else is needed to
> > expose the buffer(s) to Quick2 is left as a rather large exercise
> > for the reader(s).
> > 
> > Regards,
> > 
> > 
> > Eric
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