Sending GLMemory buffers into VAAPI plugins

[Víctor M. Jáquez L.]

On 01/04/17 at 11:08am, Matt Fischer wrote:
> Hi, I hope this is the right place for VAAPI questions, I didn't see a
> dedicated mailing list for it.  Please redirect me if I missed it. :)

Gee! This is really nice. Thanks!

In order to follow this development, the gstreamer community use
bugzilla. Please open a bug here

https://bugzilla.gnome.org/enter_bug.cgi?product=GStreamer&component=gstreamer-vaapi

And upload your patch so we could make code reviews and discuss it.

> 
> I'm trying to set up a GStreamer configuration where I produce GL buffers,
> and then send them off to a VAAPI encoder.  Currently there's no direct way
> to do that without a software download in between, so I've been trying to
> figure out how to add that support.  I've hacked something together that
> seems to work, based largely on the code which is already present for
> importing dmabuf buffers.  However there are still several pieces of it
> that aren't right, and I'm not exactly sure how to proceed, so I was hoping
> somebody here could give me some guidance.
> 
> I've attached a copy of my patch as it currently stands.  Essentially I've
> just added a new block in gst_vaapi_plugin_base_get_input_buffer() which
> can detect GLMemory buffers, and which uses gst_vaapi_texture_new_wrapped()
> to get the texture into a GstVaapiSurfaceProxy.  Here are the parts I still
> haven't completely worked out:
> 
> 1. Right now I have to fake the chroma_type so that
> is_chroma_type_supported() in gstvaapiencoder.c doesn't reject the
> surface.  Is this check actually necessary when creating a VASurface the
> way I'm doing?  The colors in the encoded video seem to be right, even
> though it's an ARGB texture.
> 
> 2. I had to punch a hole through GstVaapiTexture to get at the
> GstVaapiSurface that is created in the EGL backend.  That doesn't
> generalize to the other texture backends...is there a better way for me to
> turn a GstVaapiTexture into a GstVaapiSurface that would be more portable?
> 
> 3. I'm creating a new GstVaapiTexture every time a buffer comes in, which
> obviously isn't ideal.  I'd like to cache these things somehow...maybe a
> new meta on the incoming GLMemory buffer or something like that?
> 
> 4. I had to add code to gstvaapipluginbase.c to ensure that we have a GL
> context before creating the VAAPI display.  I'm not exactly sure how this
> plays with the existing code that tried to get a GL context during
> decide_allocation for GLTextureUploadMeta.  Would that still be necessary,
> or could it just use the same mechanism that I added, which queries for the
> context like other GL plugins do?
> 
> I'd appreciate any feedback you can provide.

Besides what Hyunjun has already said, I wonder, since you're already
importing only EGLImages, why not extract the dmabuf in it and export it as a
VASurface?

vmjl

> 
> Thanks,
> Matt


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