CODEWITHSUNDEEP
qtc++11ffmpegqml
henrique vital
henrique vital

Reputation: 61

How can I record a window using ffmpeg by id?

I want to get the id of the window by name using c++ or qml and record the specific screen using this id in ffmpeg.

ffmpeg -f x11grab -wid 0x6200012 -s 1920x1052 -r 30 -i :0.0+0,0

How can I do this?

it's not necessary to be the id, can be the offset-x and offset-y, I just want to record the window in any position.

Upvotes: 3

Views: 1380

Answers (2)

Kelvin Wong
Kelvin Wong

Reputation: 71

I found out the following:

ffmpeg -y -s 800x600 -f x11grab -window_id 0x3200008 -framerate 30 -i :11.0+0,0 -c:v libx264 -preset ultrafast -crf 40 output_select_window.mp4

Very important explanation:

-window_id = 'xwininfo' shows window_id if you select a window

-i :11.0+0,0 = 11 means and from in shell with `$echo $Display`.

Upvotes: 3

eyllanesc
eyllanesc

Reputation: 243965

I do not see that x11grab can record some screen by id as this answer indicates so as that answer points out one option is to use GStreamer:

gst-launch-1.0 ximagesrc xid=0x04000007 ! videoconvert ! autovideosink

How do I get the window id in Qt?

  • If QQmlApplicationEngine is used with Window or ApplicationWindow:

    #include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QWindow>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/main.qml"));
    QObject::connect(&engine, &QQmlApplicationEngine::objectCreated,
                     &app, [url, &engine](QObject *obj, const QUrl &objUrl) {
        if (!obj && url == objUrl)
            QCoreApplication::exit(-1);
        if(QWindow *w = qobject_cast<QWindow *>(engine.rootObjects().first())){
            qDebug() << w->winId();
        }
    }, Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

  • With QQuickView

    #include <QGuiApplication>
#include <QQuickView>

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    QQuickView view;

    const QUrl url(QStringLiteral("qrc:/main.qml"));
    view.setSource(url);
    view.show();
    qDebug() << view.winId();
    return app.exec();
}

  • Qt Widgets:

#include "mainwindow.h"

#include <QApplication>
#include <QDebug>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    qDebug() << w.winId();
    return a.exec();
}

Or in general you should access the QWindow and get the window id:

for(QWindow *w : QGuiApplication::allWindows()){
    qDebug() << w->winId();
}

Upvotes: 3

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