Microsoft DirectX 8.1 (C++)

ICaptureGraphBuilder::FindInterface

Note   The ICaptureGraphBuilder interface is deprecated.

Looks for the specified interface on the filter, upstream and downstream from the filter, and, optionally, only on the output pin of the given category.

Syntax

HRESULT FindInterface(
    const GUID *pCategory,
    IBaseFilter *pf,
    REFIID riid,
    void **ppint
);

Parameters

pCategory

[in] Pointer to a GUID specifying the output pin category. See Pin Property Set for a list of all pin categories. NULL indicates search all the output pins regardless of category.

pf

[in] Pointer to the IBaseFilter interface of the filter.

riid

[in] Reference ID of the desired interface.

ppint

[out] Address of a void pointer. If the interface was found, this method initializes ppint so that it contains the address of a pointer to the found interface. Call the Release method to decrement the reference count when you're done with the interface.

Return Value

Returns an HRESULT value.

Remarks

This method looks for the interface on the filter, and upstream and downstream of the filter, unless a category is given. If a category is given, it only looks downstream of the output pin of that category. It can be used to find interfaces on renderers, multiplexers, TV tuners, crossbars, and so forth.

If pCategory equals &LOOK_UPSTREAM_ONLY, then the graph builder will look upstream of the filter given in parameter pf, but not on the filter itself, nor downstream of the filter.

If pCategory equals &LOOK_DOWNSTREAM_ONLY, then the graph builder will look downstream of the filter given in parameter pf, but not on the filter itself, nor upstream of the filter.

For example, capture graphs can have two crossbars in them, a video crossbar (upstream of the video capture filter) and an audio crossbar (upstream of the video crossbar). You can find the video crossbar filter that implements the IAMCrossbar interface, as shown in the following code. 

IAMCrossbar *pVideoCrossbar;
FindInterface(NULL, pVideoCaptureFilter, IID_IAMCrossbar, (void **)&pVideoCrossbar);

You can then find the IAMCrossbar filter of the audio crossbar, as shown in the following code. 

IBaseFilter *pBaseFilter;
IAMCrossbar *pAudioCrossbar;
pVideoCrossbar->QueryInterface(IID_IBaseFilter, (void **)pBaseFilter);
FindInterface(
    &LOOK_UPSTREAM_ONLY, pBaseFilter, IID_IAMCrossbar, (void **)&pAudioCrossbar);
pBaseFilter->Release();

See Also