This document includes the steps of using libva buffer sharing, the way to build and run corresponding example.
Signed-off-by: Chuanbo Weng <[email protected]> --- docs/Beignet.mdwn | 1 + docs/howto/libva-buffer-sharing-howto.mdwn | 66 ++++++++++++++++++++++++++++++ 2 files changed, 67 insertions(+) create mode 100644 docs/howto/libva-buffer-sharing-howto.mdwn diff --git a/docs/Beignet.mdwn b/docs/Beignet.mdwn index fea56b8..8845ea1 100644 --- a/docs/Beignet.mdwn +++ b/docs/Beignet.mdwn @@ -238,6 +238,7 @@ Documents for OpenCL application developers ------------------------------------------- - [[Cross compile|Beignet/howto/cross-compiler-howto]] - [[Kernel Optimization Guide|Beignet/optimization-guide]] +- [[Libva Buffer Sharing|Beignet/howto/libva-buffer-sharing-howto]] The wiki URL is as below: [http://www.freedesktop.org/wiki/Software/Beignet/](http://www.freedesktop.org/wiki/Software/Beignet/) diff --git a/docs/howto/libva-buffer-sharing-howto.mdwn b/docs/howto/libva-buffer-sharing-howto.mdwn new file mode 100644 index 0000000..94f1631 --- /dev/null +++ b/docs/howto/libva-buffer-sharing-howto.mdwn @@ -0,0 +1,66 @@ +Libva Buffer Sharing HowTo +========================== + +Beignet has extensions (clCreateBufferFromLibvaIntel/clCreateImageFromLibvaIntel) +to share gpu buffer object with libva. So users can utilize OpenCL to do processing +on VASurface or VABuffer without buffer copy. + +Prerequisite +----------------------------------- + +Libva api version >= 0.36.0. Please check your libva api version by command +`pkg-config --modversion libva`. + +Steps +--------------------------------------------------------- + +In order to use the extension clCreateBufferFromLibvaIntel/clCreateImageFromLibvaIntel +in your program, please follow the steps as below (We have added an example of using +clCreateImageFromLibvaIntel, please read next section for details): + +- Get the address of this extension by the function: + clGetExtensionFunctionAddress("clCreateBufferFromLibvaIntel") + or clGetExtensionFunctionAddress("clCreateImageFromLibvaIntel") + +- Invoke vaAcquireBufferHandle to get VASurface/VABuffer's handle, which you want + to do processing by OpenCL. + +- Use clCreateBufferFromLibvaIntel/clCreateImageFromLibvaIntel to create corresponding + cl memory object from VASurface/VABuffer's handle. You should use clCreateImageFromLibvaIntel + to create a cl image object from VASurface, because VASurface is a tiling gpu buffer + object. And we suggest use clCreateBufferFromLibvaIntel to create a cl buffer object + from VABuffer. + +- Use OpenCL to do post-processing. + +- Release this cl buffer object by clReleaseMemObject. + +- Unlock this VABuffer by vaReleaseBufferHandle. + +Sample code +------------------------------------------------- + +We have developed an example of using clCreateImageFromLibvaIntel in examples/libva_buffer_sharing +directory. This example read a source nv12 file to a VASurface, and create a target VASurface. +Then create corresponding cl image objects from them. After using ocl to change this VASurface +to a gray image, target VASurface is saved as a file. + +- Add option -DBUILD_EXAMPLES=ON to enable building examples when running cmake, such as: + `> mkdir build` + `> cd build` + `> cmake -DBUILD_EXAMPLES=ON ../` + +- Build source code: + `> make` + +- Run: + `> cd examples` + `> . ../utests/setenv.sh` + `> ./example-libva_buffer_sharing` + +You can use gst-launch-1.0 to see the result(nv12 image). Just install gstreamer1.0-plugins-base, +gstreamer1.0-plugins-bad and gstreamer1.0-x by apt on Ubuntu. Then running the following +command: + `> gst-launch-1.0 filesrc location=file_name ! videoparse format=nv12 width=xxx height=xxx \ + ! imagefreeze ! videoconvert ! video/x-raw, format=BGRx ! ximagesink` + -- 1.9.1 _______________________________________________ Beignet mailing list [email protected] http://lists.freedesktop.org/mailman/listinfo/beignet
