Zero copy to OpenGLES texture

[Sebastian Dröge]

On Fr, 2014-02-28 at 23:38 +0000, Chris Tapp wrote:
> Hi Sebastian,
> 
> On 26 Feb 2014, at 08:57, Chris Tapp <opensource at keylevel.com> wrote:
> 
> > Hi Sebastian,
> > 
> > On 25 Feb 2014, at 22:27, Sebastian Dröge <sebastian at centricular.com> wrote:
> > 
> >> On Di, 2014-02-25 at 21:58 +0000, Chris Tapp wrote:
> >>> Are there any examples showing how to use a video frame as an OpenGLES 2 texture without copying the image using glTexImage2d?
> >>> 
> >>> I've got access to the egl image extensions (eglCreateImageKHR), etc., but I can't work out how to convert the buffer into a texture.
> >>> 
> >>> As a further complication, it looks as if the target hardware doesn't support pixmaps - if it did, eglCreatePixmapSurfaceHI would probably be the way to go.
> >>> 
> >>> Is there some way to wrap a pointer to the frame in a buffer to give either a pbuffer or VGImage which I can then pass to eglCreateImageKHR?
> >>> 
> >>> I'm using Gstreamer 0.10 as 1.0 isn't available for the target.
> >> 
> >> Take a look at gst-omx and eglglessink (from gst-plugins-bad). On the
> >> Raspberry Pi those together can exchange EGLImages and render them
> >> zero-copy.
> > 
> > Thanks, I'll have a look at those.
> > 
> >> In general this will be fairly straightforward with 1.x these days, in
> >> 0.10 it's going to be rather painful unfortunately.
> > 
> > I'll first have a good look to see if 1.x is possible on my platform then ;-)
> 
> The good news (for me) is that 1.x is now available :-)
> 
> What should I be looking at to get zero copy to texture going?

As said, take a look at eglglessink and gst-omx's video decoder code :)
And in general the libgstegl lib from gst-plugins-bad too.

There's a GstMemory subclass that wraps a EGLImage and can be passed
between GStreamer elements if all of them support that. And the sink can
use glEGLImageTargetTexture2DOES() on that, or alternatively the decoder
could also put the GstVideoGLTextureUploadMeta on the buffers containing
the EGLImage memory.

-- 
Sebastian Dröge, Centricular Ltd - http://www.centricular.com
Expertise, Straight from the Source
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