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PFND3D11_1DDI_VIDEOPROCESSORSETSTREAMALPHA callback function (d3d10umddi.h)

  • Article

Sets the planar alpha for an input stream on the video processor.

Syntax

PFND3D11_1DDI_VIDEOPROCESSORSETSTREAMALPHA Pfnd3d111DdiVideoprocessorsetstreamalpha;

void Pfnd3d111DdiVideoprocessorsetstreamalpha(
  D3D10DDI_HDEVICE unnamedParam1,
  D3D11_1DDI_HVIDEOPROCESSOR unnamedParam2,
  UINT unnamedParam3,
  BOOL unnamedParam4,
  FLOAT unnamedParam5
)
{...}

Parameters

unnamedParam1

hDevice [in]

A handle to the display device (graphics context).

unnamedParam2

hVideoProcessor [in]

A handle to the video processor object that was created through a call to the CreateVideoProcessor function.

unnamedParam3

StreamIndex [in]

The zero-based index of the input stream.

unnamedParam4

Enable [in]

If TRUE, alpha blending is to be enabled on the video processor.

unnamedParam5

Alpha [in]

A pointer to a FLOAT value that specifies the planar alpha value. The value can range from 0.0 (transparent) to 1.0 (opaque).

Note  If the Enable parameter is FALSE, this parameter is ignored.
 

Return value

None

Remarks

By default, alpha blending is disabled.

For each pixel, the destination color value is computed as follows:

Cd = Cs * (As * Ap * Ae) + Cd * (1.0 - As * Ap * Ae)

where:

  • Cd = The color value of the destination pixel
  • Cs = The color value of the source pixel
  • As = The per-pixel source alpha
  • Ap = The planar alpha value
  • Ae = The palette-entry alpha value, or 1.0
Note  Palette-entry alpha values apply only to palettized color formats, and only when the device advertises support for the D3D11_1DDI_VIDEO_PROCESSOR_FEATURE_CAPS_ALPHA_PALETTE capability through the GetVideoProcessorCaps function. Otherwise, this factor equals 1.0.
 
The destination alpha value is computed according to the alpha fill mode. For more information, see VideoProcessorSetOutputAlphaFillMode

The driver reports its ability to support stereo alpha blending for an input stream in the D3D11_1DDI_VIDEO_PROCESSOR_CAPS structure that is returned through the GetVideoProcessorCaps function. If the driver supports the D3D11_1DDI_VIDEO_PROCESSOR_FEATURE_CAPS_ALPHA_STREAM capability, it can be enabled or disabled to produce stereo video frames.

Note  If the driver does not support the D3D11_1DDI_VIDEO_PROCESSOR_FEATURE_CAPS_STEREO capability, the Microsoft Direct3D runtime does not call the VideoProcessorSetStreamAlpha function.
 

Requirements

Requirement Value
Minimum supported client Windows 8
Minimum supported server Windows Server 2012
Target Platform Desktop
Header d3d10umddi.h (include D3d10umddi.h)

See also

CreateVideoProcessor

D3D11_1DDI_VIDEO_PROCESSOR_CAPS

GetVideoProcessorCaps

VideoProcessorSetOutputAlphaFillMode