qt-everywhere-src-5.15.1/qtmultimedia/src/plugins/wmf/player/mfaudioendpointcontrol.cpp

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#include "QtCore/qdebug.h"
#include "mfaudioendpointcontrol.h"

#include <mmdeviceapi.h>

MFAudioEndpointControl::MFAudioEndpointControl(QObject *parent)
    : QAudioOutputSelectorControl(parent)
    , m_currentActivate(0)
{
}

MFAudioEndpointControl::~MFAudioEndpointControl()
{
    clear();
}

void MFAudioEndpointControl::clear()
{
    m_activeEndpoint.clear();

    for (auto it = m_devices.cbegin(), end = m_devices.cend(); it != end; ++it)
         CoTaskMemFree(it.value());

    m_devices.clear();

    if (m_currentActivate)
        m_currentActivate->Release();
    m_currentActivate = NULL;
}

QList<QString> MFAudioEndpointControl::availableOutputs() const
{
    return m_devices.keys();
}

QString MFAudioEndpointControl::outputDescription(const QString &name) const
{
    return name.section(QLatin1Char('\\'), -1);
}

QString MFAudioEndpointControl::defaultOutput() const
{
    return m_defaultEndpoint;
}

QString MFAudioEndpointControl::activeOutput() const
{
    return m_activeEndpoint;
}

void MFAudioEndpointControl::setActiveOutput(const QString &name)
{
    if (m_activeEndpoint == name)
        return;
    QMap<QString, LPWSTR>::iterator it = m_devices.find(name);
    if (it == m_devices.end())
        return;

    LPWSTR wstrID = *it;
    IMFActivate *activate = NULL;
    HRESULT hr = MFCreateAudioRendererActivate(&activate);
    if (FAILED(hr)) {
        qWarning() << "Failed to create audio renderer activate";
        return;
    }

    if (wstrID) {
        hr = activate->SetString(MF_AUDIO_RENDERER_ATTRIBUTE_ENDPOINT_ID, wstrID);
    } else {
        //This is the default one that has been inserted in updateEndpoints(),
        //so give the activate a hint that we want to use the device for multimedia playback
        //then the media foundation will choose an appropriate one.

        //from MSDN:
        //The ERole enumeration defines constants that indicate the role that the system has assigned to an audio endpoint device.
        //eMultimedia: Music, movies, narration, and live music recording.
        hr = activate->SetUINT32(MF_AUDIO_RENDERER_ATTRIBUTE_ENDPOINT_ROLE, eMultimedia);
    }

    if (FAILED(hr)) {
        qWarning() << "Failed to set attribute for audio device" << name;
        return;
    }

    if (m_currentActivate)
        m_currentActivate->Release();
    m_currentActivate = activate;
    m_activeEndpoint = name;
}

IMFActivate*  MFAudioEndpointControl::createActivate()
{
    clear();

    updateEndpoints();

    // Check if an endpoint is available ("Default" is always inserted)
    if (m_devices.count() <= 1)
        return NULL;

    setActiveOutput(m_defaultEndpoint);

    return m_currentActivate;
}

void MFAudioEndpointControl::updateEndpoints()
{
    m_defaultEndpoint = QString::fromLatin1("Default");
    m_devices.insert(m_defaultEndpoint, NULL);

    IMMDeviceEnumerator *pEnum = NULL;
    HRESULT hr = CoCreateInstance(__uuidof(MMDeviceEnumerator),
                          NULL, CLSCTX_ALL,
                          __uuidof(IMMDeviceEnumerator),
                         (void**)&pEnum);
    if (SUCCEEDED(hr)) {
        IMMDeviceCollection *pDevices = NULL;
        hr = pEnum->EnumAudioEndpoints(eRender, DEVICE_STATE_ACTIVE, &pDevices);
        if (SUCCEEDED(hr)) {
            UINT count;
            hr = pDevices->GetCount(&count);
            if (SUCCEEDED(hr)) {
                for (UINT i = 0; i < count; ++i) {
                    IMMDevice *pDevice = NULL;
                    hr = pDevices->Item(i, &pDevice);
                    if (SUCCEEDED(hr)) {
                        LPWSTR wstrID = NULL;
                        hr = pDevice->GetId(&wstrID);
                        if (SUCCEEDED(hr)) {
                            QString deviceId = QString::fromWCharArray(wstrID);
                            m_devices.insert(deviceId, wstrID);
                        }
                        pDevice->Release();
                    }
                }
            }
            pDevices->Release();
        }
        pEnum->Release();
    }
}