[Libva] encode surfaces created from prime fd (backed by OpenGL 2D texture)

[Víctor M. Jáquez L.]

On 05/25/16 at 09:45am, Víctor M. Jáquez L. wrote:
> On 05/25/16 at 01:22am, Anon wrote:
> > Hi All,
> > 
> > I want to implement the following use case on Intel Haswell CPU with HD
> > graphics:
> > 
> > offscreen OpenGL rendering to OpenGL 2D texture -> use
> > EGL_MESA_image_dma_buf_export
> > to export the texture as prime fd -> vaCreateSurfaces from the prime fd ->
> > use vaapi to hw acclerate h264 encoding
> > 
> > Is this supported by the latest va-api and libva-intel-driver release
> > (i.e., 1.7.0)? If so, is there any example I can start with?
> > 
> > I did read the sample application h264encode.c and thought it might be a
> > good starting point. However, the first major issue I encountered is when
> > creating context through vaCreateContext, a number of pre-allocated va
> > surfaces are required and thus statically associated with the new va
> > context. However, with prime fd, the fd will change so a new va surface is
> > created with every new prime fd. I don't see any API can be used to
> > dynamically add/remove va surfaces after the context is created. Can you
> > please give me some suggestions?
> 
> You can look at the gstreamer-vaapi[1] code, which supports it, though right
> now is under discussion and rewriting.
> 
> 1. https://cgit.freedesktop.org/gstreamer/gstreamer-vaapi

Ugh... morning coffee is not kicking yet.

This specific pipeline is not supported out-of-the-box, perhaps hacking
gldownload element to export dmabuf elements from a specific texture grabber
by glsrcbin. I don't know the details.

Anyway, from the VA side, afaik, encoders/decoders need pre-allocate the
output surfaces, not the input ones.

You can associate the prime fd to a surface and encode it. Don't release the
fd until the surface is already processed.

vmjl