The CBasicAudio class handles the IDispatch interface component of the IBasicAudio interface and leaves the properties and methods of IBasicAudio pure virtual to be implemented by a derived filter class.
The CBasicAudio::GetIDsOfNames, CBasicAudio::GetTypeInfo, CBasicAudio::GetTypeInfoCount, and CBasicAudio::Invoke member functions are standard implementations of the IDispatch interface using the CBaseDispatch class (and a type library) to parse the commands and pass them to the pure virtual IBasicAudio methods.
Microsoft® DirectShow uses units of 100th of a decibel for the volume scale. A value of 0 indicates maximum volume supported by the device. A value of 10,000 is the minimum volume (normally silence). Balance is expressed in the range 10,000 to 10,000, with 0 being neutral. A negative balance value means that the right channel is attenuated by this dB value (that is, it is quieter). Similarly, a positive balance value means that the right channel is louder than the left; that is, the left channel is attenuated by the corresponding negative decibel value.
Member Functions
| Name | Description |
| CBasicAudio | Constructs a CBasicAudio object. |
Implemented INonDelegatingUnknown Methods
| Name | Description |
| NonDelegatingQueryInterface | Returns a specified reference-counted interface. |
Implemented IDispatch Methods
| Name | Description |
| GetIDsOfNames | Maps a single member and an optional set of parameters to a corresponding set of integer dispatch identifiers, which can be used during subsequent calls to the CBasicAudio::Invoke member function. |
| GetTypeInfo | Retrieves a type-information object, which can retrieve the type information for an interface. |
| GetTypeInfoCount | Retrieves the number of type-information interfaces provided by an object. |
| Invoke | Provides access to properties and methods exposed by an object. |
Constructs a CBasicAudio object.
CBasicAudio(
const TCHAR *pName,
LPUNKNOWN pUnk
);
No return value.
Allocate the pName parameter in static memory. This name appears on the debugging terminal when the object is created and deleted.
Maps a single member function and an optional set of parameters to a corresponding set of integer dispatch identifiers, which can be used upon subsequent calls to the CBasicAudio::Invoke member function.
HRESULT GetIDsOfNames(
REFIID riid,
OLECHAR ** rgszNames,
UINT cNames,
LCID lcid,
DISPID * rgdispid
);
Returns one of the following values.
| Value | Meaning |
| DISP_E_UNKNOWN_CLSID | The CLSID was not recognized. |
| DISP_E_UNKNOWNNAME | One or more of the names were not known. The returned DISPIDs contain DISPID_UNKNOWN for each entry that corresponds to an unknown name. |
| E_OUTOFMEMORY | Out of memory. |
| S_OK | Success. |
Retrieves a type-information object, which can retrieve the type information for an interface.
HRESULT GetTypeInfo(
UINT itinfo,
LCID lcid,
ITypeInfo ** pptinfo
);
Returns an E_POINTER if pptinfo is invalid. Returns TYPE_E_ELEMENTNOTFOUND if itinfo is not zero. Returns S_OK if is successful. Otherwise, returns an HRESULT from one of the calls to retrieve the type. The HRESULT indicates the error and can be one of the following standard constants, or other values not listed:
| Value | Meaning |
| E_FAIL | Failure. |
| E_POINTER | Null pointer argument. |
| E_INVALIDARG | Invalid argument. |
Retrieves the number of type-information interfaces provided by an object.
HRESULT GetTypeInfoCount(
UINT * pctinfo
);
Returns E_POINTER if pctinfo is invalid; otherwise, returns S_OK.
Provides access to properties and methods exposed by an object.
HRESULT Invoke(
DISPID dispidMember,
REFIID riid,
LCID lcid,
WORD wFlags,
DISPPARAMS * pdispparams,
VARIANT * pvarResult,
EXCEPINFO * pexcepinfo,
UINT * puArgErr
);
Returns DISP_E_UNKNOWNINTERFACE if riid is not IID_NULL. Returns one of the error codes from CBasicAudio::GetTypeInfo if the call fails. Otherwise, returns the HRESULT from the call to IDispatch::Invoke.
Returns a specified reference-counted interface.
HRESULT NonDelegatingQueryInterface(
REFIID riid,
void **ppv
);
Returns E_POINTER if ppv is invalid. Returns NOERROR if the query is successful or E_NOINTERFACE if it is not.
Returns pointers to the IBasicAudio and IUnknown interfaces by default. Override this member function to publish any additional interfaces implemented by the derived class.
This member function implements the INonDelegatingUnknown::NonDelegatingQueryInterface method.
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