Vaapi. The ability to add input types to the decoders plugin: GstVideoGLTextureMeta and DMABuf

[Víctor Jáquez]

On Wed, 22 Aug 2018 at 15:12, Alexander Yanin wrote:
> > Adding memory:DMABuf caps feature in vaapipostproc sink pad is not
> > implemented. BUT, dmabuf-based buffers don't need to use that caps feature
> > *if they are mappable to user-space*.
> 
> > gldownload can pass dmabuf-based buffers without memory:DMABuf caps feature, as
> > far as I understand. And vaapipostproc can detect if that buffer is dmabuf-based
> > and upload it onto a VA surface (no copy is involved).
> 
> > There is no need to duplicate the code in vaapipostroc in the encoders, when you
> > can just prepend vaapiproc in the pipeline.
> 
> How could gldownload figure out to pass DMABuf instead of raw memory
> if the elements negotiated video/x-raw caps? For example, I've tested
> this pipeline:

Indeed, there's now a code path in gldownload to verify if the generated buffers
are mappable.

I just quick hacked gldownload

diff --git a/ext/gl/gstgldownloadelement.c b/ext/gl/gstgldownloadelement.c
index aefc289ee..429bcb4d2 100644
--- a/ext/gl/gstgldownloadelement.c
+++ b/ext/gl/gstgldownloadelement.c
@@ -137,14 +137,14 @@ gst_gl_download_element_set_caps (GstBaseTransform * bt, GstCaps * in_caps,
   if (gst_caps_features_contains (features, GST_CAPS_FEATURE_MEMORY_GL_MEMORY)) {
     /* do nothing with the buffer */
 #if GST_GL_HAVE_PLATFORM_EGL && GST_GL_HAVE_DMABUF
-  } else if (gst_caps_features_contains (features,
-          GST_CAPS_FEATURE_MEMORY_DMABUF)) {
+  } else {
     dl->dmabuf_allocator = gst_dmabuf_allocator_new ();
-#endif
-  } else if (gst_caps_features_contains (features,
-          GST_CAPS_FEATURE_MEMORY_SYSTEM_MEMORY)) {
+  }
+#else
+  } else {
     dl->do_pbo_transfers = TRUE;
   }
+#endif
 
   return TRUE;
 }


And it seems to work.

The other option is to implement in vaapipostproc the negotiation of
memory:DMABuf caps feature.

vmjl

> 
> gst-launch-1.0 gltestsrc is-live=true ! glvideomixer ! gldownload !
> vaapipostproc ! vaapivp8enc ! webmmux ! filesink location=test.webm
> 
> SVG of this pipeline is attached.
> 
> It is doubtful that gldownload uses DMABuf in this case.
> If I use caps filter with 'memory:DMABuf' specified, negotiation fails.
> 
> Alex


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