sharingDX9Inc.adoc

General information about sharing memory objects with DX9 follows.

The goal of this extension is to allow applications to use media surfaces as OpenCL memory objects. This allows efficient sharing of data between OpenCL and selected adapter APIs (only DX9 for now). If this extension is supported, an OpenCL image object can be created from a media surface and the OpenCL API can be used to execute kernels that read and/or write memory objects that are media surfaces. Note that OpenCL memory objects may be created from the adapter media surface if and only if the OpenCL context has been created from that adapter.

If this extension is supported by an implementation, the string "cl_khr_dx9_media_sharing" will be present in the CL_PLATFORM_EXTENSIONS (see clGetPlatformInfo) or CL_DEVICE_EXTENSIONS (see clGetDeviceInfo).

As currently proposed the interfaces for this extension would be provided in cl_dx9_media_sharing.h.

Surface formats for Media Surface Sharing

This section includes the D3D surface formats that are supported when the adapter type is one of the Direct 3D lineage. Using a D3D surface format not listed here is an error. To extend the use of this extension to support media adapters beyond DirectX9 tables similar to the ones in this section will need to be defined for the surface formats supported by the new media adapter. All implementations that support this extension are required to support the NV12 surface format, the other surface formats supported are the same surface formats that the adapter you are sharing with supports as long as they are listed in the tables below (Tables 9.10.3 and 9.10.4).

FOUR CC code	CL image format (channel order, channel data type)
FOURCC('N', 'V', '1', '2'), Plane 0	CL_R, CL_UNORM_INT8
FOURCC('N', 'V', '1', '2'), Plane 1	CL_RG, CL_UNORM_INT8
FOURCC('Y', 'V', '1', '2'), Plane 0	CL_R, CL_UNORM_INT8
FOURCC('Y', 'V', '1', '2'), Plane 1	CL_R, CL_UNORM_INT8
FOURCC('Y', 'V', '1', '2'), Plane 2	CL_R, CL_UNORM_INT8

In the table above, NV12 Plane 0 corresponds to the luminance (Y) channel and Plane 1 corresponds to the UV channels. The YV12 Plane 0 corresponds to the Y channel, Plane 1 to the U channel and Plane 2 to the V channel. Note that the YUV formats map to CL_R and CL_RG but do not perform any YUV to RGB conversion and vice-versa.

D3D format	CL image format (channel order, channel data type)
D3DFMT_R32F	CL_R, CL_FLOAT
D3DFMT_R16F	CL_R, CL_HALF_FLOAT
D3DFMT_L16	CL_R, CL_UNORM_INT16
D3DFMT_A8	CL_A, CL_UNORM_INT8
D3DFMT_L8	CL_R, CL_UNORM_INT8
D3DFMT_G32R32F	CL_RG, CL_FLOAT
D3DFMT_G16R16F	CL_RG, CL_HALF_FLOAT
D3DFMT_G16R16	CL_RG, CL_UNORM_INT16
D3DFMT_A8L8	CL_RG, CL_UNORM_INT8
D3DFMT_A32B32G32R32F	CL_RGBA, CL_FLOAT
D3DFMT_A16B16G16R16F	CL_RGBA, CL_HALF_FLOAT
D3DFMT_A16B16G16R16	CL_RGBA, CL_UNORM_INT16
D3DFMT_A8B8G8R8	CL_RGBA, CL_UNORM_INT8
D3DFMT_X8B8G8R8	CL_RGBA, CL_UNORM_INT8
D3DFMT_A8R8G8B8	CL_BGRA, CL_UNORM_INT8
D3DFMT_X8R8G8B8	CL_BGRA, CL_UNORM_INT8

Note that D3D9 format names seem to imply that the order of the color channels are switched relative to OpenCL but this is not the case. For example, layout of channels for each pixel for D3DFMT_A32FB32FG32FR32F is the same as CL_RGBA, CL_FLOAT.

Properties of media surface objects may be queried using clGetMemObjectInfo and clGetImageInfo with param_name CL_MEM_DX9_MEDIA_ADAPTER_TYPE_KHR, CL_MEM_DX9_MEDIA_SURFACE_INFO_KHR and CL_IMAGE_DX9_MEDIA_SURFACE_PLANE_KHR.