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MF_MT_GEOMETRIC_APERTURE attribute

Defines the geometric aperture for a video media type.

Data type

Byte array

Remarks

The value of this attribute is an MFVideoArea structure.

The picture aspect ratio is calculated relative to the geometric aperture, using the following formula: Picture aspect ratio = (geometric aperture width / geometric aperture height) × pixel aspect ratio.

If this attribute is not set, the geometric aperture is assumed to be the entire video frame. You should set this attribute only when the media type describes a video standard with a defined active area.

For example, in NTSC television the video frame is 720 × 480 with an active area of 704 × 480 and a 10:11 pixel aspect ratio. The resulting picture has an aspect ratio of (704/480) × (10/11) = 4:3.

Note  The default presenter for the Enhanced Video Renderer (EVR) shows the geometric aperture of the video, if specified.

The GUID constant for this attribute is exported from mfuuid.lib.

Examples


HRESULT SetGeometricAperture(
    IMFMediaType *pMediaType, 
    const MFVideoArea& area
    )
{
    return pMediaType->SetBlob(
        MF_MT_GEOMETRIC_APERTURE, 
        (UINT8*)&area, 
        sizeof(MFVideoArea)
        );
}

Requirements

Minimum supported client

Windows Vista [desktop apps | Windows Store apps]

Minimum supported server

Windows Server 2008 [desktop apps | Windows Store apps]

Header

Mfapi.h

See also

Media Foundation Attributes
Picture Aspect Ratio
Video Media Types
IMFAttributes::GetBlob
IMFAttributes::SetBlob
IMFMediaType
MF_MT_MINIMUM_DISPLAY_APERTURE
MF_MT_PAN_SCAN_APERTURE

 

 

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