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4/8/2010

Negotiates the allocator to use, which uses the allocator from the upstream output pin.

Syntax 

HRESULT DecideAllocator(
  IMemInputPin* 
pPin,
  IMemAllocator** 
ppAlloc 
);

Parameters

pPin

Pointer to the IMemInputPininterface of the downstream input pin.

ppAlloc

Returned allocator pointer.

Return Value

Returns NOERROR if successful. Otherwise, returns VFW_E_NO_ALLOCATOR if there is no allocator, or an error from calling GetAllocator, InitAllocator, GetAllocatorRequirements, DecideBufferSize, or NotifyAllocator.

Remarks

This member function overrides the CBaseOutputPin::DecideAllocatormember function.

This implementation uses the allocator that is negotiated by its input pin because a transform-inplace filter does not supply its own allocator. It then calls IMemInputPin::NotifyAllocatoron the downstream input pin with that allocator.

If you want to use your own allocator, it is better to derive from CTransformFilterthan from CTransInPlaceFilter, because the purpose of a transform-inplace filter is to use an existing allocator.

Requirements

Windows Embedded CE Windows CE 2.12 and later
Note Microsoft DirectShow applications and DirectShow filters have different include file and Library requirements
For more information, see Setting Up the Build Environment,
Version 2.12 requires DXPAK 1.0 or later