IVMRSurfaceAllocator::AllocateSurface 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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 AllocateSurface method allocates a DirectDraw surface.

Syntax

HRESULT AllocateSurface(
  [in]  DWORD_PTR            dwUserID,
  [in]  VMRALLOCATIONINFO    *lpAllocInfo,
  [in]  DWORD                *lpdwActualBuffers,
  [out] LPDIRECTDRAWSURFACE7 *lplpSurface
);

Parameters

[in] dwUserID

An application-defined DWORD_PTR cookie that uniquely identifies this instance of the VMR for use in scenarios when one instance of the allocator-presenter is used with multiple VMR instances.

[in] lpAllocInfo

Specifies the VMRALLOCATIONINFO structure. See Remarks.

[in] lpdwActualBuffers

[out] On input this parameter is used to request the number of buffers desired. On output it receives the actual number of buffers created.

[out] lplpSurface

Address of a pointer that receives the Direct3D surface.

Return value

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

Remarks

Before calling AllocateSurface explicitly, a client application should call IVMRSurfaceAllocator::FreeSurface to be sure that the DirectDraw decoding surface front buffer is NULL. If it is not NULL at the time an application calls AllocateSurface, the debug version of quartz.dll will cause an assertion.

When implementing this method in a custom allocator-presenter, you must examine the value of lpAllocInfo->lpHdr->biBitCount. If biBitCount is zero, then you must set it to the pixel depth for the current display. If BiBitCount is left at zero, the surface allocation will fail and a new (default) VMR will be created.

Requirements

See also

Error and Success Codes

IVMRSurfaceAllocator Interface

Using the Video Mixing Renderer