C++ Qt5+；如何为QMediaPlayer设置默认音频设备

我有一个使用Qt的程序，我需要让它使用用户在首选项中选择的输出设备播放声音。我可以通过调用以下代码列出windows中的所有可用设备：

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

QList devices=QAudioDeviceInfo:：availableDevices（QAudio:：AudioOutput）；
foreach（QAudioDeviceInfo i，设备）
此->用户界面->组合框->添加项（i.deviceName（））；

但是，我不知道如何更改作为应用程序默认设备的设备，以便

QMediaPlayer

使用该设备播放所有声音，而不是默认设备。我该怎么做？我对仅限windows的Qt5+特定解决方案很满意，尽管跨平台解决方案可能是最好的

基本上，我希望实现类似的首选项对话框，如Microsoft Lync中的此对话框：

---

据微软称：Windows7引入了可以实现这一点的API。但是我不知道这是如何记录的，在哪里记录的。

看起来你应该这样做（玩家是QMediaPlayer*）：

您必须为创建的每个QMediaPlayer应用以下修复程序：

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);
    }
}

QMediaPlayer*player=新的QMediaPlayer（此）；
QMediaService*svc=player->service（）；
如果（svc！=nullptr）
{
QAudioOutputSelectorControl*out=重新解释
（svc->requestControl（QAudioOutputSelectorControl_iid））；
if（out！=nullptr）
{
新的MFAudioEndpointControl_Fixed_Helper（out）；//我尝试了上面的解决方案，但不太成功。因此我将我的解决方案放在这里。它在win10上也可以正常工作（相同的方法-未记录的API）：

首先添加到.pro文件：

QT += axcontainer


然后添加以下修改以适应QT头（名称：PolicyConfig.h）


mb这将帮助你@MikeMinaev我已经读过了，它没有帮助，因为它没有说明程序员如何更改默认设备的信息。我只能在Qt4中找到如何使用声子进行此操作，但QT5中没有信息根据我认为你不能更改它，我认为这是系统设置，你不能更改，但是t这是有魔力的。是的，我在上一个稳定的Qt（5.4）中也发现了这些bug://@Petr更新了答案。现在包括一个修复程序。你使用了哪种编译器？
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);
    }
}

QT += axcontainer

// ----------------------------------------------------------------------------
// 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
};

#ifndef DEFAULTOUTPUT_H
#define DEFAULTOUTPUT_H

#include <QString>
#include <QHash>

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

#endif

#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;
    }
}

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() );
}

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