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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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

The GetAllocator method retrieves the memory allocator proposed by this pin. After the allocator has been selected, this method returns a pointer to the selected allocator.

Syntax

HRESULT GetAllocator(
  [out] IMemAllocator **ppAllocator
);

Parameters

[out] ppAllocator

Receives a pointer to the allocator's IMemAllocator interface. The caller must release the interface.

Return value

Returns an HRESULT value. Possible values include those shown in the following table.

Return code	Description
S_OK	Success.
VFW_E_NO_ALLOCATOR	No allocator is available.

Remarks

When an output pin connects to an input pin, it negotiates with the input pin to decide on a memory allocator. The output pin calls this method to retrieve the input pin's proposed allocator. It calls the IMemInputPin::NotifyAllocator method to specify which allocator it selected.

If this method succeeds, the IMemAllocator interface has an outstanding reference count. Be sure to release it when you are done.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	strmif.h (include Dshow.h)
Library	Strmiids.lib