Re: QtMultimedia on i.MX6

[Thomas Senyk <thomas.senyk@pelagicore.com>]

On Thursday, 11 July, 2013 12:58:34 Robert Winkler wrote:
> On Wed, Jul 10, 2013 at 6:30 AM, Philip Craig <phil@blackmoth.com.au> wrote:
> > On Wed, Jul 10, 2013 at 8:41 PM, Thomas Senyk
> > 
> > <thomas.senyk@pelagicore.com> wrote:
> > > On Wednesday, 10 July, 2013 20:32:05 Philip Craig wrote:
> > >> I'm not sure why it needs to be imx6 specific. Doesn't the opengl API
> > 
> > make
> > 
> > >> it so that it doesn't need to be specific? The Qt eglfs platform is
> > 
> > using
> > 
> > >> the vivante opengl libraries. As I understand it, the parts that need
> > 
> > to be
> > 
> > >> imx6 specific are confined to the eglfs platform plugin.
> > >> 
> > >> qt-gstreamer is at http://cgit.freedesktop.org/gstreamer/qt-gstreamer
> > > 
> > > No. There is no vendor-independent way to map cpu/vpu based memory into
> > 
> > gpu
> > 
> > > (/opengl) memory.
> > > Without 'mapping' one needs to copy/upload via glTexImage2D.
> > > This one single line(!) consumes >100% cpu of one iMX6 core  for 1080p.
> > > If you 'map' the cpu load is very easily <10%
> 
> I was under the same impression as Philip that OpenGL does provide the
> functions glMapBuffer and glMapBufferRange.  Standard OpenGL does provide
> both.
> Then I checked and OpenGL ES 2.0 does not have those functions but OpenGL
> ES 3.0 has the latter (
> https://www.khronos.org/opengles/sdk/docs/man3/xhtml/glMapBufferRange.xml).
> 
> So to clarify, if the i.MX 6 did support OpenGL ES 3 would that qualify as
> a vendor-independent way to map memory?  Sorry it's slightly unrelated I'm
> just curious.

Possibly ... partly! :)
You're still missing YUV support.
So you either have a hardware-converter (unlikely) or you got a opengl-YUV-
extensions (which is part of the vivante api)

So opengl es 3.0 + yuv-extension ... might be possible :)

But then you're back to needing a extension ;) (at least it could be vendor 
independent)


When does the imx6 get opengl es 3.0 anyway?
I've read that the chip (gc2000) is opengl es3.0 capable ..?... so it's just a 
matter of drivers?
I've already seen opengl 3.0 features ... e.g. multisample-texture support!

> 
> > Thanks for the explanation. Just to be sure I understand you: there is
> > no standard way to allocate dma buffers, so the gpu cannot do the copy
> > itself? I see that gst-plugins-gl relies on gstbufmeta from the
> > gst-fsl-plugins package to determine the physical address of dma
> > buffers allocated by the vpu plugin or by the v4l2src.
> > 
> > And yes, qt-gstreamer is using glTexImage2D. I guess that could be
> > patched, but then you may as well just patch QtMultimedia like you
> > were planning.
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