qffmpegscreencapture_dxgi.cpp

Go to the documentation of this file.

// 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 "qffmpegscreencapture_dxgi_p.h"
#include "qffmpegsurfacecapturethread_p.h"
#include <private/qabstractvideobuffer_p.h>
#include <private/qmultimediautils_p.h>
#include <private/qwindowsmultimediautils_p.h>
#include <qpa/qplatformscreen_p.h>
#include "qvideoframe.h"
 
#include <qloggingcategory.h>
#include <qwaitcondition.h>
#include <qmutex.h>
 
#include "D3d11.h"
#include "dxgi1_2.h"
 
#include <system_error>
#include <thread>
#include <chrono>
 
QT_BEGIN_NAMESPACE
 
static Q_LOGGING_CATEGORY(qLcScreenCaptureDxgi, "qt.multimedia.ffmpeg.screencapturedxgi")
 
using namespace std::chrono;
using namespace QWindowsMultimediaUtils;
using namespace Qt::StringLiterals;
 
namespace {
 
// Convenience wrapper that combines an HRESULT
// status code with an optional textual description.
class ComStatus
{
public:
    ComStatus() = default;
    ComStatus(HRESULT hr) : m_hr{ hr } { }
    ComStatus(HRESULT hr, QAnyStringView msg) : m_hr{ hr }, m_msg{ msg.toString() } { }
 
    ComStatus(const ComStatus &) = default;
    ComStatus(ComStatus &&) = default;
    ComStatus &operator=(const ComStatus &) = default;
    ComStatus &operator=(ComStatus &&) = default;
 
    explicit operator bool() const { return m_hr == S_OK; }
 
    HRESULT code() const { return m_hr; }
    QString str() const
    {
        if (!m_msg)
            return errorString(m_hr);
        return *m_msg + " " + errorString(m_hr);
    }
 
private:
    HRESULT m_hr = S_OK;
    std::optional<QString> m_msg;
};
 
template <typename T>
using ComProduct = QMaybe<ComPtr<T>, ComStatus>;
 
}
 
class QD3D11TextureVideoBuffer : public QAbstractVideoBuffer
{
public:
    QD3D11TextureVideoBuffer(const ComPtr<ID3D11Device> &device, std::shared_ptr<QMutex> &mutex,
                             const ComPtr<ID3D11Texture2D> &texture, QSize size)
        : QAbstractVideoBuffer(QVideoFrame::NoHandle)
        , m_device(device)
        , m_texture(texture)
        , m_ctxMutex(mutex)
        , m_size(size)
    {}
 
    ~QD3D11TextureVideoBuffer()
    {
        QD3D11TextureVideoBuffer::unmap();
    }
 
    QVideoFrame::MapMode mapMode() const override
    {
        return m_mapMode;
    }
 
    MapData map(QVideoFrame::MapMode mode) override
    {
        MapData mapData;
        if (!m_ctx && mode == QVideoFrame::ReadOnly) {
            D3D11_TEXTURE2D_DESC texDesc = {};
            m_texture->GetDesc(&texDesc);
            texDesc.CPUAccessFlags = D3D11_CPU_ACCESS_READ;
            texDesc.Usage = D3D11_USAGE_STAGING;
            texDesc.MiscFlags = 0;
            texDesc.BindFlags = 0;
 
            HRESULT hr = m_device->CreateTexture2D(&texDesc, nullptr, m_cpuTexture.GetAddressOf());
            if (FAILED(hr)) {
                qCDebug(qLcScreenCaptureDxgi) << "Failed to create texture with CPU access"
                                              << std::system_category().message(hr).c_str();
                qCDebug(qLcScreenCaptureDxgi) << m_device->GetDeviceRemovedReason();
                return {};
            }
 
            m_device->GetImmediateContext(m_ctx.GetAddressOf());
            m_ctxMutex->lock();
            m_ctx->CopyResource(m_cpuTexture.Get(), m_texture.Get());
 
            D3D11_MAPPED_SUBRESOURCE resource = {};
            hr = m_ctx->Map(m_cpuTexture.Get(), 0, D3D11_MAP_READ, 0, &resource);
            m_ctxMutex->unlock();
            if (FAILED(hr)) {
                qCDebug(qLcScreenCaptureDxgi) << "Failed to map texture" << m_cpuTexture.Get()
                                              << std::system_category().message(hr).c_str();
                return {};
            }
 
            m_mapMode = mode;
            mapData.nPlanes = 1;
            mapData.bytesPerLine[0] = int(resource.RowPitch);
            mapData.data[0] = reinterpret_cast<uchar*>(resource.pData);
            mapData.size[0] = m_size.height() * int(resource.RowPitch);
        }
 
        return mapData;
    }
 
    void unmap() override
    {
        if (m_mapMode == QVideoFrame::NotMapped)
            return;
        if (m_ctx) {
            m_ctxMutex->lock();
            m_ctx->Unmap(m_cpuTexture.Get(), 0);
            m_ctxMutex->unlock();
            m_ctx.Reset();
        }
        m_cpuTexture.Reset();
        m_mapMode = QVideoFrame::NotMapped;
    }
 
private:
    ComPtr<ID3D11Device> m_device;
    ComPtr<ID3D11Texture2D> m_texture;
    ComPtr<ID3D11Texture2D> m_cpuTexture;
    ComPtr<ID3D11DeviceContext> m_ctx;
    std::shared_ptr<QMutex> m_ctxMutex;
    QSize m_size;
    QVideoFrame::MapMode m_mapMode = QVideoFrame::NotMapped;
};
 
namespace {
class DxgiDuplication
{
    struct DxgiScreen
    {
        ComPtr<IDXGIAdapter1> adapter;
        ComPtr<IDXGIOutput> output;
    };
 
public:
    ~DxgiDuplication()
    {
        if (m_releaseFrame)
            m_dup->ReleaseFrame();
    }
 
    ComStatus initialize(QScreen const *screen)
    {
        const QMaybe<DxgiScreen, ComStatus> dxgiScreen = findDxgiScreen(screen);
        if (!dxgiScreen)
            return dxgiScreen.error();
 
        const ComPtr<IDXGIAdapter1> adapter = dxgiScreen->adapter;
 
        ComPtr<ID3D11Device> d3d11dev;
        HRESULT hr =
                D3D11CreateDevice(adapter.Get(), D3D_DRIVER_TYPE_UNKNOWN, nullptr, 0, nullptr, 0,
                                  D3D11_SDK_VERSION, d3d11dev.GetAddressOf(), nullptr, nullptr);
        if (FAILED(hr))
            return { hr, "Failed to create ID3D11Device device"_L1 };
 
        ComPtr<IDXGIOutput1> output;
        hr = dxgiScreen->output.As(&output);
        if (FAILED(hr))
            return { hr, "Failed to create IDXGIOutput1"_L1 };
 
        ComPtr<IDXGIOutputDuplication> dup;
        hr = output->DuplicateOutput(d3d11dev.Get(), dup.GetAddressOf());
        if (FAILED(hr))
            return { hr, "Failed to duplicate IDXGIOutput1"_L1 };
 
        m_adapter = dxgiScreen->adapter;
        m_output = output;
        m_device = d3d11dev;
        m_dup = dup;
        return { S_OK };
    }
 
    bool valid() const { return m_dup != nullptr; }
 
    QSize getFrameSize() const
    {
        DXGI_OUTDUPL_DESC outputDesc = {};
        m_dup->GetDesc(&outputDesc);
 
        return { static_cast<int>(outputDesc.ModeDesc.Width),
                 static_cast<int>(outputDesc.ModeDesc.Height) };
    }
 
    QMaybe<std::unique_ptr<QD3D11TextureVideoBuffer>, ComStatus> getNextVideoFrame()
    {
        const ComProduct<ID3D11Texture2D> texture = getNextFrame();
 
        if (!texture)
            return texture.error();
 
        return std::make_unique<QD3D11TextureVideoBuffer>(m_device, m_ctxMutex, *texture,
                                                          getFrameSize());
    }
 
private:
    ComProduct<ID3D11Texture2D> getNextFrame()
    {
        std::scoped_lock guard{ *m_ctxMutex };
 
        if (m_releaseFrame) {
            m_releaseFrame = false;
 
            HRESULT hr = m_dup->ReleaseFrame();
 
            if (hr != S_OK)
                return ComStatus{ hr, "Failed to release duplication frame."_L1 };
        }
 
        ComPtr<IDXGIResource> frame;
        DXGI_OUTDUPL_FRAME_INFO info;
 
        HRESULT hr = m_dup->AcquireNextFrame(0, &info, frame.GetAddressOf());
 
        if (hr != S_OK)
            return { unexpect, hr, "Failed to grab the screen content"_L1 };
 
        m_releaseFrame = true;
 
        ComPtr<ID3D11Texture2D> tex;
        hr = frame.As(&tex);
        if (hr != S_OK)
            return { unexpect, hr, "Failed to obtain D3D11 texture"_L1 };
 
        D3D11_TEXTURE2D_DESC texDesc = {};
        tex->GetDesc(&texDesc);
        texDesc.MiscFlags = 0;
        texDesc.BindFlags = 0;
 
        ComPtr<ID3D11Texture2D> texCopy;
        hr = m_device->CreateTexture2D(&texDesc, nullptr, texCopy.GetAddressOf());
        if (hr != S_OK)
            return { unexpect, hr, "Failed to create texture with CPU access"_L1 };
 
        ComPtr<ID3D11DeviceContext> ctx;
        m_device->GetImmediateContext(ctx.GetAddressOf());
        ctx->CopyResource(texCopy.Get(), tex.Get());
 
        return texCopy;
    }
 
    static QMaybe<DxgiScreen, ComStatus> findDxgiScreen(const QScreen *screen)
    {
        if (!screen)
            return { unexpect, E_FAIL, "Cannot find nullptr screen"_L1 };
 
        auto *winScreen = screen->nativeInterface<QNativeInterface::Private::QWindowsScreen>();
        HMONITOR handle = winScreen ? winScreen->handle() : nullptr;
 
        ComPtr<IDXGIFactory1> factory;
        HRESULT hr = CreateDXGIFactory1(IID_PPV_ARGS(&factory));
        if (FAILED(hr))
            return { unexpect, hr, "Failed to create IDXGIFactory"_L1 };
 
        ComPtr<IDXGIAdapter1> adapter;
        for (quint32 i = 0; factory->EnumAdapters1(i, adapter.ReleaseAndGetAddressOf()) == S_OK; i++) {
            ComPtr<IDXGIOutput> output;
            for (quint32 j = 0; adapter->EnumOutputs(j, output.ReleaseAndGetAddressOf()) == S_OK; ++j) {
                DXGI_OUTPUT_DESC desc = {};
                output->GetDesc(&desc);
                qCDebug(qLcScreenCaptureDxgi) << i << j << QString::fromWCharArray(desc.DeviceName);
                auto match = handle ? handle == desc.Monitor
                                    : QString::fromWCharArray(desc.DeviceName) == screen->name();
                if (match)
                    return DxgiScreen{ adapter, output };
            }
        }
        return { unexpect, DXGI_ERROR_NOT_FOUND,
                 "Could not find screen adapter "_L1 + screen->name() };
    }
 
    ComPtr<IDXGIAdapter1> m_adapter;
    ComPtr<IDXGIOutput> m_output;
    ComPtr<ID3D11Device> m_device;
    ComPtr<IDXGIOutputDuplication> m_dup;
    bool m_releaseFrame = false;
    std::shared_ptr<QMutex> m_ctxMutex = std::make_shared<QMutex>();
};
} // namespace
 
class QFFmpegScreenCaptureDxgi::Grabber : public QFFmpegSurfaceCaptureThread
{
public:
    Grabber(QFFmpegScreenCaptureDxgi &screenCapture, QScreen *screen)
        : QFFmpegSurfaceCaptureThread()
        , m_screen(screen)
    {
        setFrameRate(screen->refreshRate());
        addFrameCallback(screenCapture, &QFFmpegScreenCaptureDxgi::newVideoFrame);
        connect(this, &Grabber::errorUpdated, &screenCapture, &QFFmpegScreenCaptureDxgi::updateError);
    }
 
    ~Grabber() {
        stop();
    }
 
    void run() override
    {
        m_duplication = DxgiDuplication();
        const ComStatus status = m_duplication.initialize(m_screen);
 
        QSize frameSize = m_duplication.getFrameSize();
        QVideoFrameFormat frameFormat(frameSize, QVideoFrameFormat::Format_BGRA8888);
 
        m_formatMutex.lock();
        m_format = frameFormat;
        m_format.setFrameRate(int(frameRate()));
        m_formatMutex.unlock();
        m_waitForFormat.wakeAll();
 
        if (!status) {
            updateError(QPlatformSurfaceCapture::CaptureFailed, status.str());
            return;
        }
        QFFmpegSurfaceCaptureThread::run();
    }
 
    QVideoFrameFormat format() {
        QMutexLocker locker(&m_formatMutex);
        if (!m_format.isValid())
            m_waitForFormat.wait(&m_formatMutex);
        return m_format;
    }
 
    QVideoFrame grabFrame() override
    {
        QVideoFrame frame;
        if (!m_duplication.valid()) {
            const ComStatus status = m_duplication.initialize(m_screen);
            if (!status) {
                if (status.code() == E_ACCESSDENIED) {
                    // May occur for some time after pushing Ctrl+Alt+Del.
                    updateError(QPlatformSurfaceCapture::NoError, status.str());
                    qCWarning(qLcScreenCaptureDxgi) << status.str();
                }
                return frame;
            }
        }
 
        auto maybeBuf = m_duplication.getNextVideoFrame();
        const ComStatus &status = maybeBuf.error();
 
        if (status.code() == DXGI_ERROR_WAIT_TIMEOUT) {
            // All is good, we just didn't get a new frame yet
            updateError(QPlatformSurfaceCapture::NoError, status.str());
        } else if (status.code() == DXGI_ERROR_ACCESS_LOST) {
            // Can happen for example when pushing Ctrl + Alt + Del
            m_duplication = {};
            updateError(QPlatformSurfaceCapture::NoError, status.str());
            qCWarning(qLcScreenCaptureDxgi) << status.str();
        } else if (!status) {
            updateError(QPlatformSurfaceCapture::CaptureFailed, status.str());
            qCWarning(qLcScreenCaptureDxgi) << status.str();
        } else if (maybeBuf) {
            std::unique_ptr<QD3D11TextureVideoBuffer> buffer = std::move(*maybeBuf);
            frame = { buffer.release(), format() };
        }
 
        return frame;
    }
 
private:
    QScreen *const m_screen = nullptr;
    QWaitCondition m_waitForFormat;
    QVideoFrameFormat m_format;
    QMutex m_formatMutex;
    DxgiDuplication m_duplication;
};
 
QFFmpegScreenCaptureDxgi::QFFmpegScreenCaptureDxgi() : QPlatformSurfaceCapture(ScreenSource{}) { }
 
QFFmpegScreenCaptureDxgi::~QFFmpegScreenCaptureDxgi() = default;
 
QVideoFrameFormat QFFmpegScreenCaptureDxgi::frameFormat() const
{
    if (m_grabber)
        return m_grabber->format();
    return {};
}
 
bool QFFmpegScreenCaptureDxgi::setActiveInternal(bool active)
{
    if (static_cast<bool>(m_grabber) == active)
        return true;
 
    if (m_grabber) {
        m_grabber.reset();
    } else {
        auto screen = source<ScreenSource>();
 
        if (!checkScreenWithError(screen))
            return false;
 
        m_grabber.reset(new Grabber(*this, screen));
        m_grabber->start();
    }
 
    return true;
}
 
QT_END_NAMESPACE