CSourceStream.QueryId method
[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 It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation.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(
LPWSTR *Id
);
Parameters
-
Id
-
Pointer to a variable that receives a string containing the pin identifier.
Return value
Returns an HRESULT value. Possible values include those shown in the following table.
| Return code | Description |
|---|---|
|
Success. |
|
Insufficient memory. |
|
NULL pointer argument. |
|
Pin was not found on the filter. |
Remarks
This method implements the IPin::QueryId method. To construct an identifier string, the pin calls the CSource::FindPinNumber method with itself as the parameter. The FindPinNumber method returns the pin number, indexed from zero. QueryId increments the return value by one and converts the result to a string. For example, the first pin becomes "1"; the second pin becomes "2"; and so forth.
If this method returns VFW_E_NOT_FOUND, it indicates that the filter's array of pins is invalid, presumably caused by a bug in the filter.
Requirements
| Requirement | Value |
|---|---|
| Header |
|
| Library |
|