DXVAHD_STREAM_STATE_LUMA_KEY_DATA structure (dxvahd.h)

Specifies the luma key for an input stream, when using Microsoft DirectX Video Acceleration High Definition (DXVA-HD).

Syntax

typedef struct _DXVAHD_STREAM_STATE_LUMA_KEY_DATA {
  BOOL  Enable;
  FLOAT Lower;
  FLOAT Upper;
} DXVAHD_STREAM_STATE_LUMA_KEY_DATA;

Members

Enable

If TRUE, luma keying is enabled. Otherwise, luma keying is disabled. The default value is FALSE.

Lower

The lower bound for the luma key. The range is [0…1]. The default state value is 0.0.

Upper

The upper bound for the luma key. The range is [0…1]. The default state value is 0.0.

Remarks

To use this state, the device must support luma keying, indicated by the DXVAHD_FEATURE_CAPS_LUMA_KEY capability flag. To query for this capability, call IDXVAHD_Device::GetVideoProcessorDeviceCaps. If the device supports luma keying, it sets the DXVAHD_FEATURE_CAPS_LUMA_KEY flag in the FeatureCaps member of the DXVAHD_VPDEVCAPS structure.

If the device does not support luma keying, the IDXVAHD_VideoProcessor::SetVideoProcessStreamState method fails for this state.

If the input format is RGB, the device must also support the DXVAHD_INPUT_FORMAT_CAPS_RGB_LUMA_KEY capability. This capability flag is set in the InputFormatCaps member of the DXVAHD_VPDEVCAPS structure. If the flag is not present, the device ignores the luma key value for RGB input.

The values of Lower and Upper give the lower and upper bounds of the luma key, using a nominal range of [0...1]. Given a format with n bits per channel, these values are converted to luma values as follows:

val = f * ((1 << n)-1)

Any pixel whose luma value falls within the upper and lower bounds (inclusive) is treated as transparent.

For example, if the pixel format uses 8-bit luma, the upper bound is calculated as follows:

BYTE Y = BYTE(max(min(1.0, Upper), 0.0) * 255.0)

Note that the value is clamped to the range [0...1] before multiplying by 255.

Examples

HRESULT DXVAHD_SetLumaKey(
    IDXVAHD_VideoProcessor *pVP,
    UINT stream,
    BOOL bEnable,
    float fLower,   // Lower bound for the luma key.
    float fUpper    // Upper bound for the luma key.
    )
{
    DXVAHD_STREAM_STATE_LUMA_KEY_DATA luma = { bEnable, fLower, fUpper };

    HRESULT hr = pVP->SetVideoProcessStreamState(
        stream,
        DXVAHD_STREAM_STATE_LUMA_KEY,
        sizeof(luma),
        &luma
        );

    return hr;
}

Requirements

See also

DXVA-HD

DXVAHD_STREAM_STATE

Direct3D Video Structures

IDXVAHD_VideoProcessor::SetVideoProcessStreamState

Media Foundation Structures