qplatformmediaintegration.cpp

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// Copyright (C) 2021 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include <qtmultimediaglobal_p.h>
#include "qplatformmediaintegration_p.h"
#include <qatomic.h>
#include <qmutex.h>
#include <qplatformaudioinput_p.h>
#include <qplatformaudiooutput_p.h>
#include <qplatformaudioresampler_p.h>
#include <qplatformvideodevices_p.h>
#include <qmediadevices.h>
#include <qcameradevice.h>
#include <qloggingcategory.h>
#include <QtCore/qcoreapplication.h>
#include <QtCore/qapplicationstatic.h>
 
#include "qplatformcapturablewindows_p.h"
#include "qplatformmediadevices_p.h"
#include <QtCore/private/qfactoryloader_p.h>
#include <QtCore/private/qcoreapplication_p.h>
#include <private/qplatformmediaformatinfo_p.h>
#include "qplatformmediaplugin_p.h"
 
namespace {
 
class QFallbackIntegration : public QPlatformMediaIntegration
{
public:
    QFallbackIntegration() : QPlatformMediaIntegration(QLatin1String("fallback"))
    {
        qWarning("No QtMultimedia backends found. Only QMediaDevices, QAudioDevice, QSoundEffect, QAudioSink, and QAudioSource are available.");
    }
};
 
static Q_LOGGING_CATEGORY(qLcMediaPlugin, "qt.multimedia.plugin")
 
Q_GLOBAL_STATIC_WITH_ARGS(QFactoryLoader, loader,
                          (QPlatformMediaPlugin_iid,
                           QLatin1String("/multimedia")))
 
static const auto FFmpegBackend = QStringLiteral("ffmpeg");
 
static QString defaultBackend(const QStringList &backends)
{
#ifdef QT_DEFAULT_MEDIA_BACKEND
    auto backend = QString::fromUtf8(QT_DEFAULT_MEDIA_BACKEND);
    if (backends.contains(backend))
        return backend;
#endif
 
#if defined(Q_OS_DARWIN) || defined(Q_OS_LINUX) || defined(Q_OS_WINDOWS) || defined(Q_OS_ANDROID)
    // Return ffmpeg backend by default.
    // Platform backends for the OS list are optionally available but have limited support.
    if (backends.contains(FFmpegBackend))
        return FFmpegBackend;
#else
    // Return platform backend (non-ffmpeg) by default.
    if (backends.size() > 1 && backends[0] == FFmpegBackend)
        return backends[1];
#endif
 
    return backends[0];
}
 
struct InstanceHolder
{
    InstanceHolder()
    {
        if (!QCoreApplication::instance())
            qCCritical(qLcMediaPlugin()) << "Qt Multimedia requires a QCoreApplication instance";
 
        const QStringList backends = QPlatformMediaIntegration::availableBackends();
        QString backend = QString::fromUtf8(qgetenv("QT_MEDIA_BACKEND"));
        if (backend.isEmpty() && !backends.isEmpty())
            backend = defaultBackend(backends);
 
        qCDebug(qLcMediaPlugin) << "Loading media backend" << backend;
        instance.reset(
                qLoadPlugin<QPlatformMediaIntegration, QPlatformMediaPlugin>(loader(), backend));
 
        if (!instance) {
            // No backends found. Use fallback to support basic functionality
            instance = std::make_unique<QFallbackIntegration>();
        }
    }
 
    ~InstanceHolder()
    {
        instance.reset();
        qCDebug(qLcMediaPlugin) << "Released media backend";
    }
 
    std::unique_ptr<QPlatformMediaIntegration> instance;
};
 
Q_APPLICATION_STATIC(InstanceHolder, s_instanceHolder);
 
} // namespace
 
QT_BEGIN_NAMESPACE
 
QPlatformMediaIntegration *QPlatformMediaIntegration::instance()
{
    return s_instanceHolder->instance.get();
}
 
QList<QCameraDevice> QPlatformMediaIntegration::videoInputs()
{
    auto devices = videoDevices();
    return devices ? devices->videoDevices() : QList<QCameraDevice>{};
}
 
QMaybe<std::unique_ptr<QPlatformAudioResampler>>
QPlatformMediaIntegration::createAudioResampler(const QAudioFormat &, const QAudioFormat &)
{
    return notAvailable;
}
 
QMaybe<QPlatformAudioInput *> QPlatformMediaIntegration::createAudioInput(QAudioInput *q)
{
    return new QPlatformAudioInput(q);
}
 
QMaybe<QPlatformAudioOutput *> QPlatformMediaIntegration::createAudioOutput(QAudioOutput *q)
{
    return new QPlatformAudioOutput(q);
}
 
QList<QCapturableWindow> QPlatformMediaIntegration::capturableWindowsList()
{
    const auto capturableWindows = this->capturableWindows();
    return capturableWindows ? capturableWindows->windows() : QList<QCapturableWindow>{};
}
 
bool QPlatformMediaIntegration::isCapturableWindowValid(const QCapturableWindowPrivate &window)
{
    const auto capturableWindows = this->capturableWindows();
    return capturableWindows && capturableWindows->isWindowValid(window);
}
 
const QPlatformMediaFormatInfo *QPlatformMediaIntegration::formatInfo()
{
    std::call_once(m_formatInfoOnceFlg, [this]() {
        m_formatInfo.reset(createFormatInfo());
        Q_ASSERT(m_formatInfo);
    });
    return m_formatInfo.get();
}
 
QPlatformMediaFormatInfo *QPlatformMediaIntegration::createFormatInfo()
{
    return new QPlatformMediaFormatInfo;
}
 
std::unique_ptr<QPlatformMediaDevices> QPlatformMediaIntegration::createMediaDevices()
{
    return QPlatformMediaDevices::create();
}
 
// clang-format off
QPlatformVideoDevices *QPlatformMediaIntegration::videoDevices()
{
    std::call_once(m_videoDevicesOnceFlag,
                   [this]() {
                       m_videoDevices.reset(createVideoDevices());
                   });
    return m_videoDevices.get();
}
 
QPlatformCapturableWindows *QPlatformMediaIntegration::capturableWindows()
{
    std::call_once(m_capturableWindowsOnceFlag,
                   [this]() {
                       m_capturableWindows.reset(createCapturableWindows());
                   });
    return m_capturableWindows.get();
}
 
QPlatformMediaDevices *QPlatformMediaIntegration::mediaDevices()
{
    std::call_once(m_mediaDevicesOnceFlag, [this] {
        m_mediaDevices = createMediaDevices();
    });
    return m_mediaDevices.get();
}
 
// clang-format on
 
QStringList QPlatformMediaIntegration::availableBackends()
{
    QStringList list;
 
    if (QFactoryLoader *fl = loader()) {
        const auto keyMap = fl->keyMap();
        for (auto it = keyMap.constBegin(); it != keyMap.constEnd(); ++it)
            if (!list.contains(it.value()))
                list << it.value();
    }
 
    qCDebug(qLcMediaPlugin) << "Available backends" << list;
    return list;
}
 
QLatin1String QPlatformMediaIntegration::name()
{
    return m_backendName;
}
 
QVideoFrame QPlatformMediaIntegration::convertVideoFrame(QVideoFrame &,
                                                         const QVideoFrameFormat &)
{
    return {};
}
 
QPlatformMediaIntegration::QPlatformMediaIntegration(QLatin1String name) : m_backendName(name) { }
 
QPlatformMediaIntegration::~QPlatformMediaIntegration() = default;
 
QT_END_NAMESPACE
 
#include "moc_qplatformmediaintegration_p.cpp"