clCreateFromDX9MediaSurfaceKHR

Creates an OpenCL image object from a media surface.

cl_mem clCreateFromDX9MediaSurfaceKHR ( cl_context context,
  cl_mem_flags flags,
  cl_dx9_media_adapter_type_khr adapter_type,
  void *surface_info,
  cl_uint plane,
  cl_int  *errcode_ret )

Parameters

context

A valid OpenCL context created from a media adapter.

flags

A bit-field that is used to specify usage information. Refer to the table of allowed values for flags for clCreateBuffer. Only CL_MEM_READ_ONLY, CL_MEM_WRITE_ONLY, and CL_MEM_READ_WRITE values specified in the table of allowed values for flags for clCreateBuffer can be used.

adapter_type

A value from enumeration of supported adapters described in the table of cl_dx9_media_adapter_type_khr values for clGetDeviceIDsFromDX9MediaAdapterKHR. The type of surface_info is determined by the adapter type. The implementation does not need to support all adapter types. This approach provides flexibility to support additional adapter types in the future. Supported adapter types are CL_ADAPTER_D3D9_KHR, CL_ADAPTER_D3D9EX_KHR, and CL_ADAPTER_DXVA_KHR.

If adapter_type is CL_ADAPTER_D3D9_KHR, CL_ADAPTER_D3D9EX_KHR, or CL_ADAPTER_DXVA_KHR, the surface_info points to the following structure:

typedef struct _cl_dx9_surface_info_khr
{
    IDirect3DSurface9 *resource; HANDLE shared_handle;
} cl_dx9_surface_info_khr;
                    

For D3D9 surfaces, we need both the handle to the resource and the resource itself to have a sufficient amount of information to eliminate a copy of the surface for sharing in cases where this is possible. Elimination of the copy is driver dependent. shared_handle may be NULL and this may result in sub-optimal performance.

surface_info

A pointer to one of the structures defined in the adapter_type description above passed in as a void *.

plane

The plane of resource to share for planar surface formats. For planar formats, we use the plane parameter to obtain a handle to thie specific plane (Y, U or V for example). For nonplanar formats used by media, plane must be 0.

errcode_ret

An appropriate error code. If errcode_ret is NULL, no error code is returned.

Notes

The width and height of the returned OpenCL 2D image object are determined by the width and height of the plane of resource. The channel type and order of the returned image object is determined by the format and plane of resource and are described in tables 9.10.3 and 9.10.4.

This call will increment the internal media surface count on resource. The internal media surface reference count on resource will be decremented when the OpenCL reference count on the returned OpenCL memory object drops to zero.

DX9 Media Surface Sharing

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_media_sharing" will be present in the CL_PLATFORM_EXTENSIONS or CL_DEVICE_EXTENSIONS string described in the table of allowed values for param_name for clGetDeviceInfo.

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

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 two tables below.

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_MEDIA_ADAPTER_TYPE_KHR, CL_MEM_MEDIA_SURFACE_INFO_KHR and CL_IMAGE_MEDIA_SURFACE_PLANE_KHR as described for clGetImageInfo and in the information below about accessing mapped regions of a memory object.

Accessing mapped regions of a memory object

This section describes the behavior of OpenCL commands that access mapped regions of a memory object.

The contents of the region of a memory object and associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) mapped for writing (i.e. CL_MAP_WRITE or CL_MAP_WRITE_INVALIDATE_REGION is set in map_flags argument to clEnqueueMapBuffer or clEnqueueMapImage) are considered to be undefined until this region is unmapped.

Multiple commands in command-queues can map a region or overlapping regions of a memory object and associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) for reading (i.e. map_flags = CL_MAP_READ). The contents of the regions of a memory object mapped for reading can also be read by kernels and other OpenCL commands (such as clEnqueueCopyBuffer) executing on a device(s).

Mapping (and unmapping) overlapped regions in a memory object and/or associated memory objects (sub-buffer objects or 1D image buffer objects that overlap this region) for writing is an error and will result in CL_INVALID_OPERATION error returned by clEnqueueMapBuffer or clEnqueueMapImage.

If a memory object is currently mapped for writing, the application must ensure that the memory object is unmapped before any enqueued kernels or commands that read from or write to this memory object or any of its associated memory objects (sub-buffer or 1D image buffer objects) or its parent object (if the memory object is a sub-buffer or 1D image buffer object) begin execution; otherwise the behavior is undefined.

If a memory object is currently mapped for reading, the application must ensure that the memory object is unmapped before any enqueued kernels or commands that write to this memory object or any of its associated memory objects (sub-buffer or 1D image buffer objects) or its parent object (if the memory object is a sub-buffer or 1D image buffer object) begin execution; otherwise the behavior is undefined.

Accessing the contents of the memory region referred to by the mapped pointer that has been unmapped is undefined.

The mapped pointer returned by clEnqueueMapBuffer or clEnqueueMapImage can be used as ptr argument value to clEnqueueReadBuffer, clEnqueueWriteBuffer, clEnqueueReadBufferRect, clEnqueueWriteBufferRect, clEnqueueReadImage, and clEnqueueWriteImage, provided the rules described above are adhered to.

Errors

Returns CL_SUCCESS returns a valid non-zero 2D image object and errcode_ret is set to CL_SUCCESS if the 2D image object is created successfully. Otherwise, it returns a NULL value with one of the following error values returned in errcode_ret:

  • CL_INVALID_CONTEXT if context is not a valid context.
  • CL_INVALID_VALUE if values specified in flags are not valid or if plane is not a valid plane of resource specified in surface_info..
  • CL_INVALID_DX9_MEDIA_SURFACE_KHR if resource specified in surface_info is not a valid resource or is not associated with adapter_type (e.g., adapter_type is set to CL_ADAPTER_D3D9_KHR and resource is not a Direct3D 9 surface created in D3DPOOL_DEFAULT).
  • CL_INVALID_DX9_MEDIA_SURFACE_KHR if shared_handle specified in surface_info is not NULL or a valid handle value.
  • CL_INVALID_IMAGE_FORMAT_DESCRIPTOR if the texture format of resource is not listed in tables 9.10.3 and 9.10.4.
  • CL_INVALID_OPERATION if there are no devices in context that support adapter_type.
  • CL_OUT_OF_RESOURCES if there is a failure to allocate resources required by the OpenCL implementation on the device.
  • CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.

Specification

OpenCL Specification

Also see

cl_khr_dx9_media_sharing, clGetDeviceIDsFromDX9MediaAdapterKHR, clEnqueueAcquireDX9MediaSurfacesKHR, clEnqueueReleaseDX9MediaSurfacesKHR

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