CTransInPlaceOutputPin::DecideAllocator

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Windows Embedded CE 6.0 R3

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 IMemInputPin interface 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::DecideAllocator member 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::NotifyAllocator on the downstream input pin with that allocator.

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

Requirements