IAsyncReader::RequestAllocator

A version of this page is also available for

Windows Embedded CE 6.0 R3

4/8/2010

This method retrieves the actual allocator to be used.

Syntax

HRESULT RequestAllocator(
  IMemAllocator* pPreferred,
  ALLOCATOR_PROPERTIES* pProps,
  IMemAllocator** ppActual
);

Parameters

• pPreferred
  [in] Preferred allocator.

• pProps
  [in] Preferred allocator properties (size, count, and alignment).

• ppActual
  [out] Actual allocator used.

Return Value

Returns an HRESULT value that depends on the implementation of the interface. Current DirectShow implementation return values include the following.

Remarks

The preferred allocator and preferred allocator properties must be passed in. This method returns the actual allocator to be used.

IMemAllocator::GetProperties should be called on the returned allocator to learn the alignment and prefix chosen. This allocator will not be committed and decommitted by the asynchronous reader, only by the consumer. This method must be called before calling IAsyncReader::Request.

Requirements