IVMRMixerControl::GetAlpha method (strmif.h)
[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 GetAlpha method retrieves the constant alpha value that is applied to this video stream.
Syntax
HRESULT GetAlpha(
[in] DWORD dwStreamID,
[out] float *pAlpha
);
Parameters
[in] dwStreamID
Specifies the input stream.
[out] pAlpha
Pointer to a variable of type float that receives the current alpha value.
Return value
If the method succeeds, it returns S_OK. If it fails, it returns an error code.
| Return code | Description |
|---|---|
|
pAlpha is invalid. |
|
The pin is not connected. |
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 |