IPin::QueryId method (strmif.h)

Article
02/22/2024

[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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 QueryId method retrieves an identifier for the pin.

Syntax

HRESULT QueryId(
  [out] LPWSTR *Id
);

Parameters

[out] Id

Receives a string containing the pin identifier.

Return value

Returns an HRESULT value. Possible values include the following.

Return code	Description
S_OK	Success.
E_OUTOFMEMORY	Insufficient memory.
E_POINTER	NULL pointer argument.

Remarks

This method supports graph persistence. Use this method to save a pin's state, and the IBaseFilter::FindPin method to restore the state. The pin's identifier string is defined by the filter implementation. The identifier must be unique within the filter.

Note The pin identifier is not necessarily the same as the pin name that the QueryPinInfo method returns.

The filter allocates the returned string using the CoTaskMemAlloc function. The caller must free it using CoTaskMemFree.

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