> ## Documentation Index
> Fetch the complete documentation index at: https://devdocs.xbox.com/llms.txt
> Use this file to discover all available pages before exploring further.

# IAudioStateMonitor::UnregisterCallback 方法

> IAudioStateMonitor::UnregisterCallback 方法

# IAudioStateMonitor::UnregisterCallback 方法

取消註冊先前透過 [IAudioStateMonitor::RegisterCallback](/zh-TW/reference/audio/audiostatemonitor/interfaces/iaudiostatemonitor-registercallback) 註冊的回呼。

## 語法

```cpp theme={null}
void UnregisterCallback(
  AudioStateMonitorRegistrationHandle registration
);
```

### 參數

*registration*<br />Type: AudioStateMonitorRegistrationHandle

識別要取消註冊之回呼的 64 位元整數。此值會在 **RegisterCallback** 方法的 *registration* 參數中傳回。

### 傳回值

此方法不會傳回值。

## 備註

請考慮下列案例：遊戲只有在確知音訊不會因原則而被 OS 靜音時，才會播放 GameMedia 音訊。為此，遊戲會在預設主機端點上，註冊 [AudioCategory\_GameMedia](https://learn.microsoft.com/windows/desktop/api/audiosessiontypes/ne-audiosessiontypes-audio_stream_category) 串流類別的 SoundLevel 通知。如果此類別的 SoundLevel 設定為 'Muted'，遊戲會停止播放其 GameMedia 串流。如果 SoundLevel 設定為其他任何值，遊戲會選擇播放其 GameMedia 串流。

```cpp theme={null}
// global variables 
winrt::com_ptr<IAudioStateMonitor> g_audioStateMonitor; 
AudioStateMonitorRegistrationHandle g_registration = 0; 

// Returns true if the GameMedia stream should be disabled, false if it should be 
// enabled. 
bool IsSoundLevelMuted(_In_ IAudioStateMonitor* audioStateMonitor) 
{ 
return (audioStateMonitor->GetSoundLevel() == AudioStateMonitorSoundLevel::Muted); 
} 

HRESULT StartTrackingSoundLevel() 
{ 
// Create an AudioStateMonitor and register for callbacks from it. 
HRESULT hr = RegisterForSoundLevelChanges(); 
if (SUCCEEDED(hr)) 
{ 
// Check the current sound level and determine if the GameMedia stream should 
// be enabled. 
bool disableGameMediaStream = IsSoundLevelMuted(g_audioStateMonitor.get()); 

// Add code here that enables or disables the GameMedia stream based on the 
// value of the boolean. 
} 
return hr; 
} 

HRESULT RegisterForSoundLevelChanges() 
{ 
HRESULT hr = S_OK; 

// Create a new AudioStateMonitor for the GameMedia category, if needed, and 
// register for callbacks. 
if (m_audioStateMonitor == nullptr) 
{ 
hr = CreateRenderAudioStateMonitorForCategoryAndDeviceRole( 
AudioCategory_GameMedia, ERole::eConsole, g_audioStateMonitor.put()); 
if (SUCCEEDED(hr)) 
{ 
// Optional "context" parameter is not used in this example, 
// and is set to nullptr. 
hr = g_audioStateMonitor->RegisterCallback(OnAudioStateMonitorCallback, nullptr, &g_registration); 
} 
} 

if (FAILED(hr)) 
{ 
// g_audioStateMonitor is a smart pointer, so if an IAudioStateMonitor was 
// allocated, setting the smart pointer to null invokes the Release method 
// which will decrement its usage count and ensure that the object is properly 
// destroyed. 
g_audioStateMonitor = nullptr; 
} 
return hr; 
} 

// Unregister callbacks on program shutdown 
void UnregisterForSoundLevelChanges() 
{ 
if (g_audioStateMonitor != nullptr) 
{ 
if (g_registration) 
{ 
g_audioStateMonitor->UnregisterCallback(g_registration); 
} 

// g_audioStateMonitor is a smart pointer, so setting it to null 
// invokes the Release method to decrement its usage count. 
g_audioStateMonitor = nullptr; 
} 
} 

void OnAudioStateMonitorCallback(_In_ IAudioStateMonitor* audioStateMonitor, _In_opt_ void* context) 
{ bool disableGameMediaStream = IsSoundLevelMuted(audioStateMonitor); 

// Add code here that enables or disables the GameMedia stream based on the value 
// of the boolean. 
} 
```

## 需求

**標頭：** Audiostatemonitorapi.h

**支援的平台：** Windows、XBOX One 系列主機和 XBOX Series 主機

## 另請參閱

[IAudioStateMonitor](/zh-TW/reference/audio/audiostatemonitor/interfaces/iaudiostatemonitor)

[關於 WASAPI](https://learn.microsoft.com/en-us/windows/desktop/CoreAudio/wasapi)


## Related topics

- [IAudioStateMonitor::UnregisterCallback 方法](/zh-CN/reference/audio/audiostatemonitor/interfaces/iaudiostatemonitor-unregistercallback.md)
- [IAudioStateMonitor::UnregisterCallback method](/reference/audio/audiostatemonitor/interfaces/iaudiostatemonitor-unregistercallback.md)
- [Método IAudioStateMonitor::UnregisterCallback](/es/reference/audio/audiostatemonitor/interfaces/iaudiostatemonitor-unregistercallback.md)
- [IAudioStateMonitor::UnregisterCallback メソッド](/ja-jp/reference/audio/audiostatemonitor/interfaces/iaudiostatemonitor-unregistercallback.md)
- [IAudioStateMonitor::RegisterCallback 方法](/zh-CN/reference/audio/audiostatemonitor/interfaces/iaudiostatemonitor-registercallback.md)