Question

我有一个使用Qt的程序，我需要使用用户在首选项中选择的输出设备来播放声音。我可以通过调用以下代码列出Windows中所有可用的设备：

QList<QAudioDeviceInfo> devices = QAudioDeviceInfo::availableDevices(QAudio::AudioOutput);
foreach (QAudioDeviceInfo i, devices)
    this->ui->comboBox->addItem(i.deviceName());

但是我不知道如何更改将作为我的应用程序的默认设备的设备，以便QMediaPlayer将使用该设备播放所有声音，而不是默认设备。我怎样才能做到这一点？我很好用Windows只有Qt5 +特定的解决方案，虽然跨平台解决方案可能是最好的。

基本上我想实现类似于Microsoft Lync中的首选项对话框：

enter image description here

根据微软的说法：https://social.technet.microsoft.com/Forums/windows/en-US/b1d1acac-1f21-4d23-8d68-98964d67c2c7/assigning-an-application-to-different-sound-outputs Windows 7引入了可以做到这一点的API。但是我不知道记录的方式和位置。

Answer 1

我尝试过上述解决方案但成功率较低。所以我把我放在这里。它在win10上也能正常工作（同样的方法 - 未记录的API）：

首先添加到.pro文件中：
```
QT += axcontainer
```

然后添加以下修改后的QT标题（命名为：PolicyConfig.h）

// ----------------------------------------------------------------------------
// PolicyConfig.h
// Undocumented COM-interface IPolicyConfig.
// Use for set default audio render endpoint
// @author EreTIk
// ----------------------------------------------------------------------------


#pragma once

#include "winnt.h"
//#include <QAxAggregated>

class DECLSPEC_UUID("f8679f50-850a-41cf-9c72-430f290290c8") IPolicyConfig;
class DECLSPEC_UUID("870af99c-171d-4f9e-af0d-e63df40c2bc9") CPolicyConfigClient;
// ----------------------------------------------------------------------------
// class CPolicyConfigClient
// {870af99c-171d-4f9e-af0d-e63df40c2bc9}
//  
// interface IPolicyConfig
// {f8679f50-850a-41cf-9c72-430f290290c8}
//
// Query interface:
// CComPtr<IPolicyConfig> PolicyConfig;
// PolicyConfig.CoCreateInstance(__uuidof(CPolicyConfigClient));
// 
// @compatible: Windows 7 and Later
// ----------------------------------------------------------------------------
class IPolicyConfig : public IUnknown
{
public:

    virtual HRESULT GetMixFormat(
        PCWSTR,
        WAVEFORMATEX **
    );

    virtual HRESULT STDMETHODCALLTYPE GetDeviceFormat(
        PCWSTR,
        INT,
        WAVEFORMATEX **
    );

    virtual HRESULT STDMETHODCALLTYPE ResetDeviceFormat(
        PCWSTR
    );

    virtual HRESULT STDMETHODCALLTYPE SetDeviceFormat(
        PCWSTR,
        WAVEFORMATEX *,
        WAVEFORMATEX *
    );

    virtual HRESULT STDMETHODCALLTYPE GetProcessingPeriod(
        PCWSTR,
        INT,
        PINT64,
        PINT64
    );

    virtual HRESULT STDMETHODCALLTYPE SetProcessingPeriod(
        PCWSTR,
        PINT64
    );

    virtual HRESULT STDMETHODCALLTYPE GetShareMode(
        PCWSTR,
        struct DeviceShareMode *
    );

    virtual HRESULT STDMETHODCALLTYPE SetShareMode(
        PCWSTR,
        struct DeviceShareMode *
    );

    virtual HRESULT STDMETHODCALLTYPE GetPropertyValue(
        PCWSTR,
        const PROPERTYKEY &,
        PROPVARIANT *
    );

    virtual HRESULT STDMETHODCALLTYPE SetPropertyValue(
        PCWSTR,
        const PROPERTYKEY &,
        PROPVARIANT *
    );

    virtual HRESULT STDMETHODCALLTYPE SetDefaultEndpoint(
        __in PCWSTR wszDeviceId,
        __in ERole eRole 
    );

    virtual HRESULT STDMETHODCALLTYPE SetEndpointVisibility(
        PCWSTR,
        INT
    );
};

class DECLSPEC_UUID("568b9108-44bf-40b4-9006-86afe5b5a620") IPolicyConfigVista;
class DECLSPEC_UUID("294935CE-F637-4E7C-A41B-AB255460B862") CPolicyConfigVistaClient;
// ----------------------------------------------------------------------------
// class CPolicyConfigVistaClient
// {294935CE-F637-4E7C-A41B-AB255460B862}
//  
// interface IPolicyConfigVista
// {568b9108-44bf-40b4-9006-86afe5b5a620}
//
// Query interface:
// CComPtr<IPolicyConfigVista> PolicyConfig;
// PolicyConfig.CoCreateInstance(__uuidof(CPolicyConfigVistaClient));
// 
// @compatible: Windows Vista and Later
// ----------------------------------------------------------------------------
class IPolicyConfigVista : public IUnknown
{
public:

    virtual HRESULT GetMixFormat(
        PCWSTR,
        WAVEFORMATEX **
    );  // not available on Windows 7, use method from IPolicyConfig

    virtual HRESULT STDMETHODCALLTYPE GetDeviceFormat(
        PCWSTR,
        INT,
        WAVEFORMATEX **
    );

    virtual HRESULT STDMETHODCALLTYPE SetDeviceFormat(
        PCWSTR,
        WAVEFORMATEX *,
        WAVEFORMATEX *
    );

    virtual HRESULT STDMETHODCALLTYPE GetProcessingPeriod(
        PCWSTR,
        INT,
        PINT64,
        PINT64
    );  // not available on Windows 7, use method from IPolicyConfig

    virtual HRESULT STDMETHODCALLTYPE SetProcessingPeriod(
        PCWSTR,
        PINT64
    );  // not available on Windows 7, use method from IPolicyConfig

    virtual HRESULT STDMETHODCALLTYPE GetShareMode(
        PCWSTR,
        struct DeviceShareMode *
    );  // not available on Windows 7, use method from IPolicyConfig

    virtual HRESULT STDMETHODCALLTYPE SetShareMode(
        PCWSTR,
        struct DeviceShareMode *
    );  // not available on Windows 7, use method from IPolicyConfig

    virtual HRESULT STDMETHODCALLTYPE GetPropertyValue(
        PCWSTR,
        const PROPERTYKEY &,
        PROPVARIANT *
    );

    virtual HRESULT STDMETHODCALLTYPE SetPropertyValue(
        PCWSTR,
        const PROPERTYKEY &,
        PROPVARIANT *
    );

    virtual HRESULT STDMETHODCALLTYPE SetDefaultEndpoint(
        __in PCWSTR wszDeviceId,
        __in ERole eRole 
    );

    virtual HRESULT STDMETHODCALLTYPE SetEndpointVisibility(
        PCWSTR,
        INT
    );  // not available on Windows 7, use method from IPolicyConfig
};

添加Qt界面DefaultOutput

#ifndef DEFAULTOUTPUT_H
#define DEFAULTOUTPUT_H

#include <QString>
#include <QHash>

class DefaultOutput
{
public:
    static QHash<QString, QString>  enumOutputDevices();
    static bool                     changeOutputDevice( QString id );
};

#endif

实现文件（将其命名为DefaultOutput.cpp）：

#include <stdio.h>
#include <wchar.h>
#include <tchar.h>
#include "windows.h"
#include "Mmdeviceapi.h"
#include "PolicyConfig.h"
#include "Propidl.h"
#include "Functiondiscoverykeys_devpkey.h"
#include "defaultoutput.h"

QHash<QString, QString> DefaultOutput::enumOutputDevices()
{
    QHash<QString, QString> list;

    try
    {
        HRESULT hr = CoInitialize( NULL );
        if( FAILED( hr ) )
            return list;
        IMMDeviceEnumerator *pEnum = NULL;
        // Create a multimedia device enumerator.
        hr = CoCreateInstance( __uuidof( MMDeviceEnumerator ), NULL, CLSCTX_ALL, __uuidof( IMMDeviceEnumerator ), (void**)&pEnum );
        if( FAILED( hr ) )
            return list;
        IMMDeviceCollection *pDevices;
        // Enumerate the output devices.
        hr = pEnum->EnumAudioEndpoints( eRender, DEVICE_STATE_ACTIVE, &pDevices );
        if( FAILED( hr ) )
            return list;
        UINT count;
        pDevices->GetCount(&count);
        if( FAILED( hr ) )
            return list;
        for( UINT i = 0; i < count; i++ )
        {
            IMMDevice *pDevice;
            hr = pDevices->Item( i, &pDevice );
            if( SUCCEEDED( hr ) )
            {
                LPWSTR wstrID = NULL;
                hr = pDevice->GetId( &wstrID );
                if( SUCCEEDED( hr ) )
                {
                    IPropertyStore* pStore;
                    hr = pDevice->OpenPropertyStore( STGM_READ, &pStore );
                    if( SUCCEEDED( hr ) )
                    {
                        PROPVARIANT friendlyName;
                        PropVariantInit( &friendlyName );
                        hr = pStore->GetValue( PKEY_Device_FriendlyName, &friendlyName );
                        if( SUCCEEDED( hr ) )
                        {
                            QString qid = QString::fromStdU16String( (char16_t*)wstrID );
                            QString qname = QString::fromStdU16String( (char16_t*)friendlyName.pwszVal );
                            list[qid] = qname;
                            PropVariantClear( &friendlyName );
                        }

                        pStore->Release();
                    }
                }

                pDevice->Release();
            }
        }

        pDevices->Release();
        pEnum->Release();
        return list;
    }
    catch( ... )
    {
        return list;
    }
}

bool DefaultOutput::changeOutputDevice( QString id )
{
    try
    {
        IPolicyConfigVista* pPolicyConfig;
        ERole reserved = eConsole;
        HRESULT hr = CoCreateInstance( __uuidof( CPolicyConfigVistaClient ), NULL, CLSCTX_ALL, __uuidof( IPolicyConfigVista ), (LPVOID*)&pPolicyConfig );
        if( SUCCEEDED( hr ) )
        {
            hr = pPolicyConfig->SetDefaultEndpoint( (PCWSTR)id.toStdU16String().data(), reserved );
            pPolicyConfig->Release();
            return SUCCEEDED( hr );
        }
        else
            return false;
    }
    catch( ... )
    {
        return false;
    }
}

枚举用法示例：

QHash<QString, QString> devices = DefaultOutput::enumOutputDevices();
for( QHash<QString, QString>::iterator iter = devices.begin(); iter != devices.end(); iter++ )
{
    ui->devicesComboBox->addItem( iter.value(), iter.key() );
}

设置当前默认设备示例：

int index = ui->devicesComboBox->currentIndex();
QString deviceId = ui->devicesComboBox->itemData( index ).toString();
DefaultOutput::changeOutputDevice( deviceId );

Answer 2

看起来你应该做这样的事情（玩家是QMediaPlayer *）：

QMediaService *svc = player->service();
if (svc != nullptr)
{
    QAudioOutputSelectorControl *out = qobject_cast<QAudioOutputSelectorControl *>
                                       (svc->requestControl(QAudioOutputSelectorControl_iid));
    if (out != nullptr)
    {
        out->setActiveOutput(this->ui->comboBox->currentText());
        svc->releaseControl(out);
    }
}

但由于this和this，我无法在Win7安装中测试此内容。

<强>更新

嗯，这是我做的修复（使用Desktop_Qt_5_4_0_MSVC2013_32 / 64-Debug / Release测试;您可能需要更改不同工具链的vtable代码）：

如何获取具有“友好名称”的设备列表（键 - 名称;值 - deviceID）：

auto outputs = MFAudioEndpointControl_Fixed::availableOutputsFriendly();
for (auto it = outputs.cbegin(), e = outputs.cend(); it != e; ++it)
{
    this->ui->comboBox->addItem(it.key(), it.value());
    this->ui->plainTextEdit->appendPlainText(it.key() + " (" + it.value() + ")");
}

您必须为您创建的每个QMediaPlayer应用以下修复：

QMediaPlayer *player = new QMediaPlayer(this);

QMediaService *svc = player->service();
if (svc != nullptr)
{
    QAudioOutputSelectorControl *out = reinterpret_cast<QAudioOutputSelectorControl*>
                                       (svc->requestControl(QAudioOutputSelectorControl_iid));
    if (out != nullptr)
    {
        new MFAudioEndpointControl_Fixed_Helper(out); // <- the fix; notice that it's a HELPER class

        out->setActiveOutput(this->ui->comboBox->itemData(this->ui->comboBox->currentIndex()).toString()); // we have to pass deviceID, not the name
        svc->releaseControl(out);
    }
}

Qt5 +如何为QMediaPlayer设置默认音频设备

2 个答案: