CBaseAllocator::SetProperties

  • Articolo
 
Microsoft DirectShow 9.0

CBaseAllocator::SetProperties

The SetProperties method specifies the number of buffers to allocate and the size of each buffer. This method implements the IMemAllocator::SetProperties method.

Syntax

  HRESULT SetProperties(
    ALLOCATOR_PROPERTIES *pRequest,
    ALLOCATOR_PROPERTIES *pActual
);

Parameters

pRequest

Pointer to an ALLOCATOR_PROPERTIES structure that contains the buffer requirements.

pActual

Pointer to an ALLOCATOR_PROPERTIES structure that receives the actual buffer properties.

Return Value

Returns one of the following HRESULT values.

Value Description
S_OK Success.
E_POINTER NULL pointer argument.
VFW_E_ALREADY_COMMITTED Cannot change allocated memory while the filter is active.
VFW_E_BADALIGN An invalid alignment was specified.
VFW_E_BUFFERS_OUTSTANDING One or more buffers are still active.

Remarks

This method specifies the buffer requirements, but does not allocate any buffers. Call the CBaseAllocator::Commit method to allocate buffers.

The caller allocates two ALLOCATOR_PROPERTIES structures. The pRequest parameter contains the caller's buffer requirements, including the number of buffers and the size of each buffer. When the method returns, the pActual parameter contains the actual buffer properties, as set by the allocator. In the base class, assuming that the method succeeds, the actual properties always match the requested properties. Derived classes might override this behavior.

The allocator must not be committed, and must not have outstanding buffers. In the base class, the alignment must equal 1. The CMemAllocator class overrides this requirement.

Requirements

**  Header:** Declared in Amfilter.h; include Streams.h.

**  Library:** Use Strmbase.lib (retail builds) or Strmbasd.lib (debug builds).

See Also