我尝试编写一些应用程序来监视音频会话(如 SndVol 所做的那样)。我激活了 IAudioSessionManager2,通过 IAudioSessionEnumerator 获取当前音频会话列表,使用音频会话管理器中的 RegisterSessionNotification 方法注册通知。但是,我的应用程序从未收到 OnSessionCreated() 通知。当然,我在这里读到了类似的主题:通知未发送 https://stackoverflow.com/questions/736084/iaudiosessionmanager2-notifications-not-sent,
IAudioSessionNotification 任何人都有工作代码 https://stackoverflow.com/questions/858974/iaudiosessionnotification-anyone-have-working-code
我仔细阅读了所有答案,但我找不到我做错了什么。这是我的代码(德尔福):
TDNAudioSessionManager = class(TDNUnknownObject, IAudioSessionNotification)
private
FManager: IAudioSessionManager2;
FList: TDNAudioSessionList;
function IsManagerValid: Boolean;
protected
procedure ActivateSessionManager(out AManager: IAudioSessionManager2);
procedure GetCurrentSessions;
// IAudioSessionNotification
function OnSessionCreated(ANewSession: IAudioSessionControl): HRESULT; stdcall;
public
constructor Create;
destructor Destroy; override;
end;
constructor TDNAudioSessionManager.Create;
begin
inherited Create;
ActivateSessionManager(FManager);
if IsManagerValid then
begin
FList := TDNAudioSessionList.Create;
FManager.RegisterSessionNotification(Self);
GetCurrentSessions;
end;
end;
destructor TDNAudioSessionManager.Destroy;
begin
if IsManagerValid then
begin
FManager.UnregisterSessionNotification(Self);
FManager := nil;
end;
FreeAndNil(FList);
inherited Destroy;
end;
function TDNAudioSessionManager.IsManagerValid: Boolean;
begin
Result := Assigned(FManager);
end;
procedure TDNAudioSessionManager.GetCurrentSessions;
var
AEnumerator: IAudioSessionEnumerator;
ASession: IAudioSessionControl;
ACount: Integer;
I: Integer;
begin
if IsManagerValid then
if FManager.GetSessionEnumerator(AEnumerator) = S_OK then
try
AEnumerator.GetCount(ACount);
for I := 0 to ACount - 1 do
begin
AEnumerator.GetSession(I, ASession);
FList.Add(ASession);
end;
finally
AEnumerator := nil;
end;
end;
function TDNAudioSessionManager.OnSessionCreated(ANewSession: IAudioSessionControl): HRESULT;
begin
FList.Add(ANewSession);
Result := S_OK;
end;
procedure TDNAudioSessionManager.ActivateSessionManager(out AManager: IAudioSessionManager2);
var
AEnumerator: IMMDeviceEnumerator;
ADefault: IMMDevice;
ARes: HRESULT;
begin
AManager := nil;
ARes := CoCreateInstance(CLSID_MMDeviceEnumerator, nil, CLSCTX_INPROC_SERVER, IID_IMMDeviceEnumerator, AEnumerator);
if not ARes = S_OK then Exit;
if AEnumerator.GetDefaultAudioEndpoint(eRender, eConsole, ADefault) = S_OK then
try
ADefault.Activate(IID_IAudioSessionManager2, CLSCTX_INPROC_SERVER, nil, AManager);
finally
ADefault := nil;
end;
end;
initialization
CoInitializeEx(nil, COINIT_MULTITHREADED);
end.
注意:TDNUnknownObject 是实现 IUnknown 方法的类。
还有一个问题:应用程序关闭时音频会话会发送什么事件? (在 SndVol 中,它已从列表中删除)。我尝试了 OnSessionDisconnected、OnStateChanged (状态为 AudioSessionExpired),但我的应用程序也从未收到它们。
提前致谢!
TDN 未知对象:
TDNUnknownObject = class(TObject, IUnknown)
protected
// IUnknown
function _AddRef: Integer; stdcall;
function _Release: Integer; stdcall;
function QueryInterface(const IID: TGUID; out Obj): HRESULT; virtual; stdcall;
end;
function TDNUnknownObject._AddRef: Integer; stdcall;
begin
Result := -1;
end;
function TDNUnknownObject._Release: Integer; stdcall;
begin
Result := -1;
end;
function TDNUnknownObject.QueryInterface(const IID: TGUID; out Obj): HRESULT; stdcall;
begin
if GetInterface(IID, Obj) then
Result := S_OK
else
Result := E_NOINTERFACE;
end;