作者:丿车荣璇 | 来源:互联网 | 2023-02-04 14:52
为VideoOutput
QML对象提供自定义帧源到底需要做什么?
VideoOuput
本身是否QAbstractVideoSurface
向“源” 提供类的实例 ?
Qt5文档说了有关提供此问题的以下内容:
如果要扩展自己的C ++类以与VideoOutput互操作,则可以为基于QObject的类提供mediaObject属性,该属性公开具有可用QVideoRendererControl的QMediaObject派生类,也可以为基于QObject的类提供可写videoSurface属性可以接受基于QAbstractVideoSurface的类,并且可以遵循正确的协议向其提供QVideoFrame。
根据以下文档,我执行了以下操作:
我implmented我自己的类myFrameProvider
来源于QObject
具有可写的videoSurface
属性。
使一个类连接到以下类,该类将帧发送到myFrameProvider。
实例化myFrameProvider
类,并使其在与“ VideoOutput”小部件相同的QML上下文中可访问。
之后-每当访问“ videSurface”属性时,我都会遇到段错误。我应该设置自己的视频界面属性吗?
1> Jan Osch..:
在遇到类似问题时,我偶然发现了您的问题。不久之后,我找到了一个对我有用的解决方案。即使您的问题比较老,并且您可能继续前进,我也想分享我的答案,以帮助其他人。
我在QT文档的“使用低级视频帧”部分中找到了答案。在那里发布的那段代码作为起点非常有用,但是我必须对其进行修改,以使其正常运行。一个最小的工作示例如下所示:
FrameProvider.h
#include
#include
#include
class FameProvider : public QObject
{
Q_OBJECT
Q_PROPERTY(QAbstractVideoSurface *videoSurface READ videoSurface WRITE setVideoSurface)
public:
QAbstractVideoSurface* videoSurface() const { return m_surface; }
private:
QAbstractVideoSurface *m_surface = NULL;
QVideoSurfaceFormat m_format;
public:
void setVideoSurface(QAbstractVideoSurface *surface)
{
if (m_surface && m_surface != surface && m_surface->isActive()) {
m_surface->stop();
}
m_surface = surface;
if (m_surface && m_format.isValid())
{
m_format = m_surface->nearestFormat(m_format);
m_surface->start(m_format);
}
}
void setFormat(int width, int heigth, int format)
{
QSize size(width, heigth);
QVideoSurfaceFormat format(size, format);
m_format = format;
if (m_surface)
{
if (m_surface->isActive())
{
m_surface->stop();
}
m_format = m_surface->nearestFormat(m_format);
m_surface->start(m_format);
}
}
public slots:
void onNewVideoContentReceived(const QVideoFrame &frame)
{
if (m_surface)
m_surface->present(frame);
}
};
main.qml
import QtQuick 2.9
import QtQuick.Controls 2.2
import QtQuick.Controls.Material 2.2
import QtMultimedia 5.4
import com.yourcompany.FrameProvider 1.0
ApplicationWindow {
objectName: "mainWindow"
visible: true
width: 640
height: 480
FrameProvider{
objectName: "provider"
id: provider
}
VideoOutput {
id: display
objectName: "display"
anchors.top: parent.top
anchors.bottom: parent.bottom
width: parent.width
source: provider
}
}
main.cpp
#include
#include
int main(int argc, char *argv[])
{
// initialize the qml application engine
QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;
//register the custom control to the qml application engine
qmlRegisterType("com.yourcompany.FrameProvider", 1, 0, "FrameProvider");
// start the view
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
if (engine.rootObjects().isEmpty())
{
return -1;
}
// find your custom control
QObject *rootObject = engine.rootObjects().first();
Qobject *display = rootObject->findChild("display");
auto provider = qvariant_cast(display->property("source"));
// Create your custom frame source class, which inherits from QObject. This source is expected to have the following public fields and signals:
// - int width
// - int height
// - int format (following QVideoFrame::PixelFormat)
// - signals: void newFrameAvailable(const QVideoFrame &frame);
CustomFramesource source;
// Set the correct format for the video surface (Make sure your selected format is supported by the surface)
provider->setFormat(source.width,source.height, source.format);
// Connect your frame source with the provider
QObject::connect(&source, SIGNAL(newFrameAvailable(const QVideoFrame &)), provider, SLOT(onNewVideoContentReceived(const QVideoFrame &)));
// run the app
int retVal = app.exec();
return 0;
}
MWE来自我的实际代码,因此未经测试。我希望它无论如何都能运行并显示所有需要的步骤。