IVMRMixerControl::SetAlpha method (strmif.h)

Article
02/22/2024

[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 SetAlpha method sets a constant alpha value that is applied to this video stream.

Syntax

HRESULT SetAlpha(
  [in] DWORD dwStreamID,
  [in] float Alpha
);

Parameters

[in] dwStreamID

Specifies the input stream.

[in] Alpha

Specifies the alpha blending value to be applied to all the pixels in this stream.

Return value

If the method succeeds, it returns S_OK. If it fails, it returns an error code.

Return code	Description
VFW_E_NOT_CONNECTED	The pin is not connected.

Remarks

The alpha value specified can be between 0.0 (fully transparent) and 1.0 (full opaque).

Requirements

Requirement	Value
Minimum supported client	Windows XP with SP1 [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Target Platform	Windows
Header	strmif.h (include Dshow.h)
Library	Strmiids.lib