IVMRMixerBitmap9::SetAlphaBitmap method (vmr9.h)

Articolo
4/26/2023

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The SetAlphaBitmap method specifies a new bitmap image and the source location of the bitmap and how and where it should be rendered on the destination rectangle.

Syntax

HRESULT SetAlphaBitmap(
  [in] const VMR9AlphaBitmap *pBmpParms
);

Parameters

[in] pBmpParms

Pointer to a VMR9AlphaBitmap structure that contains information about the bitmap.

Return value

The method returns an HRESULT. Possible values include those in the following table.

Return code	Description
S_OK	The method succeeded.
E_POINTER	pBmpParms is NULL.
E_INVALIDARG	Invalid argument. See Remarks.
E_OUTOFMEMORY	Could not create a destination DC or DIBSection for the bitmap.
E_FAIL	BitBlt to bitmap surface failed.

Remarks

To remove the bitmap, set the VMR9AlphaBitmap_Disable flag in the VMR9AlphaBitmap structure and call SetAlphaBitmap again.

The application can provide the bitmap either as a Direct3D surface or as a GDI bitmap. To use a Direct3D surface, set the pDDS member of the VMR9AlphaBitmap structure. To use a GDI bitmap, set the hdc member of the structure.

The bitmap is mixed onto the video frame by the VMR's mixer component. The mixer draws the bitmap once per frame. If you change the bitmap while the filter graph is paused or stopped, the mixer does not use the new bitmap until the graph restarts. You can work around this limitation by calling IMediaControl::StopWhenReady, although a better solution is to write a custom allocator-presenter to draw the bitmap. For more information, see Supplying a Custom Allocator-Presenter for VMR-9.

If the method returns E_INVALIDARG, possible reasons include the following:

The Direct3D surface was not allocated from the D3DPOOL_SYSTEMMEM pool.
Invalid surface format. If a Direct3D surface is used, the surface format must be D3DFMT_X8R8G8B8 or D3DFMT_A8R8G8B8. If the surface format is D3DFMT_A8R8G8B8, the VMR9AlphaBitmap_SrcColorKey flag cannot be used.
The source rectangle (rSrc) exceeds the boundaries of the Direct3D surface.
The source rectangle is empty.
The source rectangle exceeds the maximum texture width or maximum texture height for the Direct3D device. To find the maximum texture size, call IDirect3DDevice9::GetDeviceCaps.
The dwFilterMode member contains an invalid combination of flags.

Include DShow.h and D3d9.h before Vmr9.h.

Requirements

Requirement	Value
Minimum supported client	Windows XP with SP2 [desktop apps only]
Minimum supported server	Windows Server 2003 R2 [desktop apps only]
Target Platform	Windows
Header	vmr9.h
Library	Strmiids.lib

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