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.

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

See also

Alphabetical List of Media Foundation Attributes

Media Foundation Attributes

Picture Aspect Ratio

Video Media Types

IMFAttributes::GetBlob

IMFAttributes::SetBlob

IMFMediaType

MF_MT_MINIMUM_DISPLAY_APERTURE

MF_MT_PAN_SCAN_APERTURE