ZeroCopy + AppSink + VAAPI + Qt

[Timtchenko, Michael]

Hi folks,

i'm trying to implement an efficient, zero copy image handling on a EGL-System without a window manager. Unfortunately this seems to be a quite hard job. :-/

My application uses the following pipeline:

"udpsrc port=55555 caps=\"application/x-rtp, media=(string)video, clock-rate=(int)90000, encoding-name=(string)H264, payload=(int)96\" "
                                         "! rtph264depay "
                                         "! vaapih264dec "
                                         "! vaapipostproc name=postproc "
                                         "! video/x-raw, format=RGBA "
                                         "! appsink name=sink emit-signals=true sync=false max-buffers=1 drop=true"

As you can see, i'm using vaapi elements as well as the appsink. I'm getting notified by signal, when a new frame is received.
Afterwards i'm pulling the frame by the following code:

#####

GstSample* sample = gst_app_sink_pull_sample( m_data->appSink );
GstBuffer* buffer = gst_sample_get_buffer( sample );

GstMapInfo* map = new GstMapInfo();
gst_buffer_map( buffer, map, GST_MAP_READ );

and access the data by

map->data()

####

This is the status quo, but my goal is to put/bind the data into a texture and render it within the qt screnegraph without any additional copy actions. To achieve this,
I need to get a already rendered texture or a direct access to the framebuffer object. Currently i'm  uploading the data with the OpenGL-function glTexImage2D which isn't very efficient at all.

In (1) they said, that this can be done by:

[...Using memory:VASurface you can map it as a normal gst video frame:
gst_video_frame_map ...]

Unfortunately i don't have a clue, how i can access a texture or a framebufferobject
from the VASurface. Is that even possible?

Is there someone who can share his knowledge? Any help is welcome! :)

Thanks in advance,
Michael

(1) http://gstreamer-devel.966125.n4.nabble.com/How-to-use-VAAPI-appsink-with-zero-copy-mmap-td4688670.html


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