Fixed and updated OpenCL-VA interoperability

[mshabunin]

resolves #18307
supersedes #18318

• added cl_va_api_media_sharing_intel.h to OpenCL headers
• added ability to build with old and new header name (did not check with old file though)
• simplified WITH_VA_INTEL handling
• updated documentation
• use clGePlatformInfo directly to read device name

How to enable the feature:

# prerequisite: libva-dev
cmake -DWITH_VA=ON -DWITH_VA_INTEL=ON ../opencv

Checked in --privileged Ubuntu 20.04 container with system libva2 and OpenCL runtime 20.37.17906:

# ../build/bin/example_va_intel_va_intel_interop ../opencv/samples/data/lena.jpg a b
libva info: VA-API version 1.7.0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/iHD_drv_video.so
libva info: Found init function __vaDriverInit_1_7
libva info: va_openDriver() returns 0
VA display opened successfully
Interop ON : processing time, msec: 1.26111

Note: device name reading have been replaced due to an error with PlatformInfo constructor

Thread 1 "example_va_inte" received signal SIGSEGV, Segmentation fault.
0x00007ffff2fce128 in clGetDeviceIDs () from /lib/x86_64-linux-gnu/libOpenCL.so.1
(gdb) bt
#0  0x00007ffff2fce128 in clGetDeviceIDs () from /lib/x86_64-linux-gnu/libOpenCL.so.1
#1  0x00007ffff4649aff in OPENCL_FN_clGetDeviceIDs_switch_fn (p1=0x7ffff2fa18e0, p2=4294967295, p3=0, p4=0x0,
    p5=0x7fffffffe114)
    at /opencv/modules/core/src/opencl/runtime/autogenerated/opencl_core_impl.hpp:411
#2  0x00007ffff462bbd8 in cv::ocl::getDevices (devices=std::vector of length 0, capacity 0, platform=0x7ffff2fa18e0)
    at /opencv/modules/core/src/ocl.cpp:6521
#3  0x00007ffff462be21 in cv::ocl::PlatformInfo::Impl::Impl (this=0x55555644c1c0, id=0x555555902860)
    at /opencv/modules/core/src/ocl.cpp:6544
#4  0x00007ffff462c029 in cv::ocl::PlatformInfo::PlatformInfo (this=0x7fffffffe220, platform_id=0x555555902860)
    at /opencv/modules/core/src/ocl.cpp:6567
...

[alalek]

Please replace platform => &platform.

With verbose replacements it is better to keep original code (to avoid replacement back):

#if 0  // code doesn't works due to ...
   original code
#else
  ... verbose code ...
#endif

[Odianosen25]

Thanks for this @mshabunin, still couldn't figure out how to fix it.

Please also is there anyway to support if someone has OpenCL 2.2 installed? I think the the only issue was the version was not specified somewhere or something.

You guys are the best

[mshabunin]

@Odianosen25 , OpenCL 2.2 should be backward compatible with 1.x. For example, I tested it with 2.1 runtime.

[Odianosen25]

@mshabunin,

Thanks for the response, and yes it actually is. Just gives out a warning

In file included from /usr/include/CL/cl.h:20,
                 from /tmp/opencv-4.4.0/modules/core/include/opencv2/core/opencl/runtime/autogenerated/opencl_core.hpp:102,
                 from /tmp/opencv-4.4.0/modules/core/include/opencv2/core/opencl/runtime/opencl_core.hpp:68,
                 from /tmp/opencv-4.4.0/modules/core/src/dxt.cpp:44:
/usr/include/CL/cl_version.h:22:104: note: #pragma message: cl_version.h: CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 220 (OpenCL 2.2)
   22 | #pragma message("cl_version.h: CL_TARGET_OPENCL_VERSION is not defined. Defaulting to 220 (OpenCL 2.2)")
      |                                                                                                        ^

But its no show stopper.

Kind regards