Name String

    cl_intel_d3d11_nv12_media_sharing

Contributors

    Krzysztof Laskowski, Intel
    Ben Ashbaugh, Intel
    Eric L Palmer, Intel

Contact

    Krzysztof Laskowski, Intel (krzysztof.laskowski 'at' intel.com)

Version

    Version 4, June 25, 2014

Number

    OpenCL Extension #31

Status

    Complete

Extension Type

    OpenCL platform extension

Dependencies

    OpenCL 1.2 with cl_khr_d3d11_sharing extension support is required 
    and a D3D11 implementation supporting sharing of surfaces with 
    OpenCL is required. This extension is written against revision 19 
    of the OpenCL 1.2 Extension specification.

Overview

    The goal of this extension is to extend the interoperability between 
    OpenCL and D3D11 with planar surface formats for media applications.  
    This is designed to reuse existing D3D11 interoperability infrastructure
    defined in the OpenCL 1.2 specification.

Additions to chapter 9.11.7.4 of the OpenCL 1.2 Extension Specification

    Replace the description of CL_INVALID_D3D11_RESOURCE_KHR 
    error value under clCreateFromD3D11Texture2DKHR with:

    "CL_INVALID_D3D11_RESOURCE_KHR if <resource> is not a Direct3D 11 texture 
    resource, if <resource> was created with the D3D11_USAGE flag 
    D3D11_USAGE_IMMUTABLE, if <resource> is a multisampled texture, if a cl_mem from  
    subresource <subresource> of <resource> has already been created using 
    clCreateFromD3D11Texture2DKHR, if <resource> format is a planar format and 
    <resource> was not created with the D3D11_RESOURCE_MISC_FLAG flag 
    D3D11_RESOURCE_MISC_SHARED, or if <context> was not created against the same 
    Direct3D 11 device from which <resource> was created."

    Add the following to the section above the table 9.11.3:

    "Sharing of arrays of NV12 surfaces is supported.
    For NV12 surface format <subresource> is defined as follows:
        <subresource> = Plane + (ArraySlice * 2),
    where Plane = 0 corresponds to the luminance (Y) channel data and Plane = 1 
    corresponds to the  chrominance (UV) channel data and the ArraySlice is the 
    zero-based index for the array level to address."

    Add the following to table 9.11.3:

   "-----------------------------------------------------------------------
                 DXGI format                  CL image format
                                        (cl_channel_order, cl_channel_type)    
    ---------------------------------   -----------------------------------
    
    DXGI_FORMAT_NV12, Plane 0           CL_R, CL_UNORM_INT8
    DXGI_FORMAT_NV12, Plane 1           CL_RG, CL_UNORM_INT8
    -----------------------------------------------------------------------"

Issues

    - There is a limitation regarding using of ID3D11DeviceContext::CopySubresourceRegion
      method not allowing to copy Y and UV portions of the NV12 planar surface
      independently. This is the only known method that would allow for sharing
      of NV12 textures without D3D11_RESOURCE_MISC_SHARED flag via a staging resource.
      Therefore this functionality is disabled and only sharing of resources 
      created with D3D11_RESOURCE_MISC_SHARED flag will be supported.

Revision History

    Version 1, 2013/11/11 (Krzysztof Laskowski) - Initial version.
    Version 2, 2013/12/12 (Krzysztof Laskowski) - Added description for sharing of arrayed NV12 
                                                  surfaces
    Version 3, 2014/28/05 (Krzysztof Laskowski) - Added explanation that sharing of arrays of
                                                  NV12 surfaces is supported.
    Version 4, 2014/25/06 (Krzysztof Laskowski) - Marked as complete.