C Specification

To acquire OpenCL memory objects that have been created from a media surface, call the function

// Provided by cl_khr_dx9_media_sharing
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);
clEnqueueAcquireDX9MediaSurfacesKHR is provided by the cl_khr_dx9_media_sharing extension.

Parameters

  • command_queue is a valid command-queue.

  • num_objects is the number of memory objects to be acquired in mem_objects.

  • mem_objects is a pointer to a list of OpenCL memory objects that were created from media surfaces.

  • event_wait_list and num_events_in_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 an event object that identifies this command and can be used to query or wait for this command to complete. If event is NULL or the enqueue is unsuccessful, no event will be created and therefore it will not be possible to query the status of this command or to wait for this command to complete. If event_wait_list and event are not NULL, event must not refer to an element of the event_wait_list array.

Description

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 .

clEnqueueAcquireDX9MediaSurfacesKHR 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_events_in_wait_list > 0, or event_wait_list is not NULL and num_events_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.

See Also

cl_command_queue, cl_event, cl_khr_dx9_media_sharing, cl_mem, cl_uint

Document Notes

For more information, see the OpenCL Specification

This page is extracted from the OpenCL Specification. Fixes and changes should be made to the Specification, not directly.

Copyright

Copyright 2014-2025 The Khronos Group Inc.

SPDX-License-Identifier: CC-BY-4.0