MFOverlay Method (IMFFrame)

Mixes frames: overlays _pFrameOverlay frame over this frame. By default audio gain is calculated based on overlay size and transparency or can be specified via 'audio_gain' property.

Syntax

VB.Net
C#
Delphi
C++

Sub MFOverlay( _
   ByVal _pFrameOverlay As IMFFrame, _
   ByVal _pFrameMask As IMFFrame, _
   ByVal _nPosX As Integer, _
   ByVal _nPosY As Integer, _
   ByVal _dblAlpha As Double, _
   ByVal _bsPropsList As String, _
   ByVal _bsAudioBufferID As String _
)

void MFOverlay( 
   IMFFrame _pFrameOverlay,
   IMFFrame _pFrameMask,
   int _nPosX,
   int _nPosY,
   double _dblAlpha,
   string _bsPropsList,
   string _bsAudioBufferID
)

procedure MFOverlay( 
    _pFrameOverlay: IMFFrame;
    _pFrameMask: IMFFrame;
    _nPosX: Integer;
    _nPosY: Integer;
    _dblAlpha: Double;
    _bsPropsList: String;
    _bsAudioBufferID: String
);

void MFOverlay( 
   IMFFrame* _pFrameOverlay,
   IMFFrame* _pFrameMask,
   int _nPosX,
   int _nPosY,
   double _dblAlpha,
   BSTR* _bsPropsList,
   BSTR* _bsAudioBufferID
)

Parameters

_pFrameOverlay: frame that is used for overlay
_pFrameMask: a mask frame
_nPosX: horizontal position of overlay
_nPosY: vertical position. The position is calculated from top-left corner
_dblAlpha: transparency (0 means transparent, 1.0 means solid)
_bsPropsList: additional properties
_bsAudioBufferID: ID of audio buffer

Example

Here is an example of how to make an overlay from "Live input with file mixing sample":

/// <summary>
/// make overlay on the frame
/// </summary>
/// <param name="pFrame">frame to be overlayed</param>
private void FrameOverlay(MFFrame pFrame)
{
    if (checkBox1.Checked && textBoxFilePath2.Text != "")
    {
        MFFrame ppFrame2scaled, ppFrame2;
        m_objReader.SourceFrameGetByTime(-1, -1, out ppFrame2, "");
        ppFrame2.MFResize(eMFCC.eMFCC_Default, widthScale, heightScale, -1, out ppFrame2scaled, "", "ch2");
        pFrame.MFOverlay(ppFrame2scaled, null, posXScale, posYScale, ovAlpha, "", "ch2");
        Marshal.ReleaseComObject(ppFrame2);
        Marshal.ReleaseComObject(ppFrame2scaled);
    }
}

Reference

IMFFrame Interface
IMFFrame Members