IAudioSessionControl2::GetSessionInstanceIdentifier method (audiopolicy.h)

The GetSessionInstanceIdentifier method retrieves the identifier of the audio session instance.

Syntax

HRESULT GetSessionInstanceIdentifier(
  [out] LPWSTR *pRetVal
);

Parameters

[out] pRetVal

Pointer to the address of a null-terminated, wide-character string that receives the identifier of a particular instance of the audio session. The string is allocated by this method and must be released by the caller by calling CoTaskMemFree. For information about CoTaskMemFree, see the Windows SDK documentation.

Return value

If the method succeeds, it returns S_OK. If it fails, possible return codes include, but are not limited to, the values shown in the following table.

Remarks

Each audio session instance is identified by a unique string. This string represents a particular instance of the audio session and, unlike the session identifier, is unique across all instances. If there are two instances of the application playing, they will have different session instance identifiers. The identifier retrieved by GetSessionInstanceIdentifier is different from the session identifier, which is shared by all session instances. To get the session identifier, call IAudioSessionControl2::GetSessionIdentifier.

GetSessionInstanceIdentifier checks whether the session has been disconnected on the default device. It retrieves the identifier string that is cached by the audio client for the device. If the session instance identifier is not found, this method retrieves it from the audio engine. For example code about getting a session instance identifier, see Getting Ducking Events from a Communication Device.

Requirements

See also

IAudioSessionControl2

Using a Communication Device