IVMRMixerControl::SetMixingPrefs method (strmif.h)

Article
07/27/2023

[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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.]

Sets the mixing preferences for the stream.

Syntax

HRESULT SetMixingPrefs(
  [in] DWORD dwMixerPrefs
);

Parameters

[in] dwMixerPrefs

Bitwise OR combination of VMRMixerPrefs flags.

Return value

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

Remarks

The flags for the mixing preferences are divided into three groups: decimation, filtering, and render target. The VMRMixerPrefs enumeration defines bitmasks to isolate these flags:

MixerPref_DecimateMask
MixerPref_FilteringMask
MixerPref_RenderTargetMask

You must specify a valid flag for each group. If you want to change a single flag, you can get the current preferences, remove the flag you don't want, and add the flag you want. For example:

C++
// Get the current mixing preferences. DWORD dwPrefs; pMixControl->GetMixingPrefs(&dwPrefs); // Remove the current render target flag. dwPrefs &= ~MixerPref_RenderTargetMask; // Add the render target flag that we want. dwPrefs \|= MixerPref_RenderTargetYUV; // Set the new flags. pMixControl->SetMixingPrefs(dwPrefs);

C++

// Get the current mixing preferences.
DWORD dwPrefs;
pMixControl->GetMixingPrefs(&dwPrefs);  
// Remove the current render target flag.
dwPrefs &= ~MixerPref_RenderTargetMask;
// Add the render target flag that we want.
dwPrefs |= MixerPref_RenderTargetYUV;
// Set the new flags.
pMixControl->SetMixingPrefs(dwPrefs);

If the VMR is in renderless mode, you must set the allocator-presenter before calling SetMixingPrefs. Otherwise, the VMR cannot determine the capabilities of the Direct3D device.

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