基于OpenCV的视频图像组态 (14)：音量控制

实现代码

播放软件，慢慢地有了声音控制的需求，在网上找了一下，用Core Audio APIS 音频应用开发即可。入门稍慢，不过用起来很简单。整理了一个类供调用。

class TCbwAudioEndpointVolumeCallback;

typedef void __fastcall (__closure * TOnVoiceNotifyEvent)(bool bMuted, int fMasterVolume);

class TCbwVolumeControl {

private:

TCbwAudioEndpointVolumeCallback * EPVolEvents;

TOnVoiceNotifyEvent FOnVoiceNotify;

bool FValid;

bool __fastcall HRStatus(HRESULT hr, UnicodeString info);

void __fastcall Prework();

void __fastcall AfterWork();

int __fastcall GetMasterVolume();

void __fastcall SetMasterVolume(int value);

bool __fastcall GetMuted();

void __fastcall SetMuted(bool value);

public:

__fastcall TCbwVolumeControl();

__fastcall ~TCbwVolumeControl();

__property bool IsValid = { read = FValid };

__property int MasterVolume = { read = GetMasterVolume, write = SetMasterVolume };

__property bool Muted = { read = GetMuted, write = SetMuted };

__property TOnVoiceNotifyEvent OnVoiceNotify = { read = FOnVoiceNotify, write = FOnVoiceNotify };

void __fastcall OnNotifyFromCallback(bool bMuted, float fMasterVolume);

};

extern TCbwVolumeControl * GlobalVolumeControl;

TCbwVolumeControl * GlobalVolumeControl = NULL;

IMMDeviceEnumerator *pEnumerator = NULL;

IMMDevice *pDevice = NULL;

IAudioEndpointVolume *g_pEndptVol = NULL;

#define SAFE_RELEASE(punk) \

if ((punk) != NULL) \

{ (punk)->Release(); (punk) = NULL; }

#define EXIT_ON_ERROR(hr) \

if (FAILED(hr)) return;

__fastcall TCbwVolumeControl::TCbwVolumeControl() {

EPVolEvents = new TCbwAudioEndpointVolumeCallback;

FOnVoiceNotify = NULL;

EPVolEvents->ParentControl = this;

Prework();

}

__fastcall TCbwVolumeControl::~TCbwVolumeControl() {

AfterWork();

delete EPVolEvents;

}

bool __fastcall TCbwVolumeControl::HRStatus(HRESULT hr, UnicodeString info) {

if (FAILED(hr)) {

DRGRAPH_DEBUG(THelper::FormatString(L"CALL %s FAILED!", info));

return false;

}

return true;

}

void __fastcall TCbwVolumeControl::Prework() {

FValid = false;

pEnumerator = NULL;

pDevice = NULL;

g_pEndptVol = NULL;

GUID g_guidMyContext = GUID_NULL;

CoInitialize(NULL);

if (HRStatus(CoCreateGuid(&g_guidMyContext),

L"CoCreateGuid(&g_guidMyContext)"))

if (HRStatus(CoCreateInstance(__uuidof(MMDeviceEnumerator), NULL,

CLSCTX_INPROC_SERVER, __uuidof(IMMDeviceEnumerator),

(void**)&pEnumerator), L"CoCreateInstance"))

if (HRStatus(pEnumerator->GetDefaultAudioEndpoint(eRender, eConsole,

&pDevice), L"pEnumerator->GetDefaultAudioEndpoint"))

if (HRStatus(pDevice->Activate(__uuidof(IAudioEndpointVolume),

CLSCTX_ALL, NULL, (void**)&g_pEndptVol),

L"pDevice->Activate"))

if (HRStatus(g_pEndptVol->RegisterControlChangeNotify

((IAudioEndpointVolumeCallback*)EPVolEvents),

L"g_pEndptVol->RegisterControlChangeNotify"))

FValid = true;

}

void __fastcall TCbwVolumeControl::AfterWork() {

if (pEnumerator != NULL) {

HRStatus(g_pEndptVol->UnregisterControlChangeNotify

((IAudioEndpointVolumeCallback*) EPVolEvents),

L"g_pEndptVol->UnregisterControlChangeNotify");

}

SAFE_RELEASE(pEnumerator);

SAFE_RELEASE(pDevice);

SAFE_RELEASE(g_pEndptVol);

CoUninitialize();

}

int __fastcall TCbwVolumeControl::GetMasterVolume() {

float pfLevel = 0;

HRStatus(g_pEndptVol->GetMasterVolumeLevelScalar(&pfLevel),

L"g_pEndptVol->GetMasterVolumeLevel");

return pfLevel * 100 + 0.5;

}

void __fastcall TCbwVolumeControl::SetMasterVolume(int value) {

float fVolume = value / 100.0;

HRStatus(g_pEndptVol->SetMasterVolumeLevelScalar(fVolume,

&GUID_NULL), L"pAudioEndpointVolume->SetMasterVolumeLevelScalar");

}

void __fastcall TCbwVolumeControl::OnNotifyFromCallback(bool bMuted,

float fMasterVolume) {

if (FOnVoiceNotify)

FOnVoiceNotify(bMuted, fMasterVolume * 100 + 0.5);

}

bool __fastcall TCbwVolumeControl::GetMuted() {

int muted = false;

g_pEndptVol->GetMute(&muted);

return muted;

}

void __fastcall TCbwVolumeControl::SetMuted(bool value) {

HRStatus(g_pEndptVol->SetMute(value,

&GUID_NULL), L"pAudioEndpointVolume->SetMute");

}

演示效果

简单做了一个测试界面。

void __fastcall TMainForm::OnVoiceNotify(bool bMuted, int fMasterVolume) {
Button_Mute->EditValue = bMuted;
Button_Volume->EditValue = fMasterVolume;
}

void __fastcall TMainForm::Button_MutePropertiesEditValueChanged(TObject *Sender) {
bool muted = Button_Mute->CurEditValue;
int volume = Button_Volume->CurEditValue;
ShowStatus(THelper::FormatString(L"%d, %s", volume, muted ? L"Muted" : L"Sound"));
FVolumeControl->MasterVolume = volume;
FVolumeControl->Muted = muted;
}