clEnqueueAcquireDX9MediaSurfacesKHR

Acquire OpenCL memory objects that have been created from a media surface.

cl_int clEnqueueAcquireDX9MediaSurfacesKHR( cl_command_queue  command_queue,
  cl_uint  num_objects,
  const cl_mem *mem_objects,
  cl_uint num_events_in_wait_list,
  const cl_event  *event_wait_list ,
  cl_event *event)

Parameters

command_queue

A valid command-queue.

num_objects

The number of memory objects to be acquired in mem_objects.

mem_objects

A pointer to a list of OpenCL memory objects that were created from media surfaces.

num_events_in_wait_list, event_wait_list

Specify events that need to complete before this particular command can be executed. If event_wait_list is NULL, then this particular command does not wait on any event to complete. If event_wait_list is NULL, num_events_in_wait_list must be 0. If event_wait_list is not NULL, the list of events pointed to by event_wait_list must be valid and num_events_in_wait_list must be greater than 0. The events specified in event_wait_list act as synchronization points.

event

Returns n event object that identifies this particular command and can be used to query or queue a wait for this particular command to complete. event can be NULL in which case it will not be possible for the application to query the status of this command or queue a wait for this command to complete.

Notes

Used to acquire OpenCL memory objects that have been created from a media surface. The media surfaces are acquired by the OpenCL context associated with command_queue and can therefore be used by all command-queues associated with the OpenCL context.

OpenCL memory objects created from media surfaces must be acquired before they can be used by any OpenCL commands queued to a command-queue. If an OpenCL memory object created from a media surface is used while it is not currently acquired by OpenCL, the call attempting to use that OpenCL memory object will return CL_DX9_MEDIA_SURFACE_NOT_ACQUIRED_KHR.

If CL_CONTEXT_INTEROP_USER_SYNC is not specified as CL_TRUE during context creation, clEnqueueAcquireDX9MediaSurfacesKHR provides the synchronization guarantee that any media adapter API calls involving the interop device(s) used in the OpenCL context made before clEnqueueAcquireDX9MediaSurfacesKHR is called will complete executing before event reports completion and before the execution of any subsequent OpenCL work issued in command_queue begins. If the context was created with properties specifying CL_CONTEXT_INTEROP_USER_SYNC as CL_TRUE, the user is responsible for guaranteeing that any media adapter API calls involving the interop device(s) used in the OpenCL context made before clEnqueueAcquireDX9MediaSurfacesKHR is called have completed before calling clEnqueueAcquireDX9MediaSurfacesKHR.

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 CL_SUCCESS if the function is executed successfully. If num_objects is 0 and mem_objects is NULL then the function does nothing and returns CL_SUCCESS. Otherwise it returns one of the following errors:

  • CL_INVALID_VALUE if num_objects is zero and mem_objects is not a NULL value or if num_objects > 0 and mem_objects is NULL.
  • CL_INVALID_MEM_OBJECT if memory objects in mem_objects are not valid OpenCL memory objects or if memory objects in mem_objects have not been created from media surfaces.
  • CL_INVALID_COMMAND_QUEUE if command_queue is not a valid command-queue.
  • CL_INVALID_CONTEXT if context associated with command_queue was not created from a device that can share the media surface referenced by mem_objects.
  • CL_DX9_MEDIA_SURFACE_ALREADY_ACQUIRED_KHR if memory objects in mem_objects have previously been acquired using clEnqueueAcquireDX9MediaSurfacesKHR but have not been released using clEnqueueReleaseDX9MediaSurfacesKHR.
  • CL_INVALID_EVENT_WAIT_LIST if event_wait_list is NULL and num_event_in_wait_list > 0, or event_wait_list is not NULL and num_event_in_wait_list is 0, or if event objects in event_wait_list are not valid events.
  • 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, clCreateFromDX9MediaSurfaceKHR, clEnqueueReleaseDX9MediaSurfacesKHR, clEnqueueAcquireDX9MediaSurfacesKHR

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