IAMBufferNegotiation::SuggestAllocatorProperties method (strmif.h)

[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 SuggestAllocatorProperties method informs the pin of the application's preferred allocator properties. Call this method before the pin connects.

Syntax

HRESULT SuggestAllocatorProperties(
  [in] const ALLOCATOR_PROPERTIES *pprop
);

Parameters

[in] pprop

Pointer to an ALLOCATOR_PROPERTIES structure that contains the requested properties. A negative value for any member indicates that the pin should use its default setting for that property.

Return value

Returns an HRESULT value. Possible values include the following.

Remarks

If both pins in the connection expose the IAMBufferNegotiation interface, call this method on each pin, to ensure that one pin does not override the other.

To request a particular number of buffers, set the cBuffers member of the ALLOCATOR_PROPERTIES structure. To request a particular buffer size, set the cbBuffer member. An application typically should not specify the alignment or prefix. If the number of buffers or size of each buffer is too small, the filter graph might drop samples.

Examples

ALLOCATOR_PROPERTIES AllocProp;
AllocProp.cbAlign = -1;  // -1 means no preference.
AllocProp.cbBuffer = dwBytesPerSec *  dwLatencyInMilliseconds / 1000;
AllocProp.cbPrefix = -1;
AllocProp.cBuffers = -1;
pIAMBufferNegotiation->SuggestAllocatorProperties(&AllocProp);

Requirements

See also

Error and Success Codes

IAMBufferNegotiation Interface