phonon-gstreamer with vaapi

[VITIELLO Fabien]

Dear Mailing-list,

I'm Fabien VITIELLO. I'm new in the phonon-gstreamer mailing list.
I'm working on a project which needs to use phonon-gstreamer with vaapi from a qt player (like qmediaplayer for instance).

In my mind, the good architecture is the one as below :

qmediaplayer
phonon
phonon-gstreamer
gstreamer
gstreamer-vaapi
libva
xvba library
fglrx video driver
--------------------------------------
fglrx.ko
--------------------------------------
HD 6570 amd graphic card

I tried to use only gstreamer to play a H264 video with xvba acceleration (AMD acceleration with HD6570 card) and it works very good (only 20 % of CPU) with the following command:

# gst-launch-0.10 playbin2 uri=file:///videofile.h264 
<or>
# gst-launch-0.10 filesrc location= /videofile.h264 ! matroskademux ! vaapidecode ! vaapisink 

The video shows in fullscreen mode.

Then, I tried to install these components below in order to use the qt demo software "qmediaplayer" and make the same gstreamer pipeline:
- qt 4.8.3, 
- phonon 4.6.0 
- phonon-gstreamer 4.6.2

This doesn't work and I thought it was because decodebin2 wasn't able to call vaapidecode. 
I thought phonon-gstreamer since version 4.6 uses playbin2 as in pipeline.cpp. 

I tried to change xvimagesink to vaapisink in the x11renderer.cpp source file and the vaapidecode was called but it seems that the link between vaapidecode and vaapisink was not enabled.
Is there a location where I can find some documentation about the phonon-gstreamer project in order to create a custom pipeline using this project ? 

Thank you for your answer and for any help about this subject.

Fabien