|Microsoft DirectX 9.0|
The PrepareSurface method prepares the DirectDraw surface to have the next video frame decoded into it.
HRESULT PrepareSurface( DWORD_PTR dwUserID, LPDIRECTDRAWSURFACE7 lpSurface, DWORD dwSurfaceFlags );
[in] 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] Specifies the DirectDraw surface
[in] Double word containing the surface flags. See Remarks.
If the method succeeds, it returns S_OK. If it fails, it returns an error code.
The only flag that the VMR currently checks here is AM_GBF_NOTASYNCPOINT (0x00000002), which indicates that you are not going to fill this buffer with a sync point (keyframe).