Video plays on a new Window while launched through gstreamer in Qt6 qml application

[Thanush]

Hi,
I used the gstreamer cmd for playing a video in qt. The video is generated on a new window. How do I generate the video inside of the mainwindow on click of a button without using multimedia concepts in qml

VideoClass.cpp

VideoClass::VideoClass(QObject *parent, int argc, char *argv[])
    : QObject{parent}
{
    gst_init(&argc,&argv);
}

void VideoClass::pipelineDescription(QString path)
{
    pipeline = gst_parse_launch("playbin uri=file://" + path.toUtf8(), 0);
    gst_element_set_state(pipeline, GST_STATE_PLAYING);
}

main.cpp

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include "videoclass.h"

int main(int argc, char *argv[])
{
    QGuiApplication app(argc, argv);
    qmlRegisterType<VideoClass>("com.video",1,0,"Gstreamer");
    QQmlApplicationEngine engine;
    const QUrl url(QStringLiteral("qrc:/VideoTest/main.qml"));
    QObject::connect(
        &engine,
        &QQmlApplicationEngine::objectCreated,
        &app,
        [url](QObject *obj, const QUrl &objUrl) {
            if (!obj && url == objUrl)
                QCoreApplication::exit(-1);
        },
        Qt::QueuedConnection);
    engine.load(url);

    return app.exec();
}

main.qml

import QtQuick
import QtQuick.Controls 2.15
import com.video 1.0

Window {
    width: 640
    height: 480
    visible: true
    title: qsTr("Hello World")
    Button{
        id: mybtn
        width: 150
        height: 50
        anchors.bottom: parent.bottom
        text: "Generate"
        MouseArea{
            anchors.fill: parent
            onClicked:{
              gst.pipelineDescription("/home/thanush/big_buck_bunny_720p_1mb.mp4")
            }
        }
    }
    Gstreamer{
        id: gst
    }
}

Thanks in Advance

[SGaist]

Hi,

Your pipeline does not reference any sink hence it's opening a new window.

You should check the qmlsink example from gstreamer.

[JoeCFD]

@SGaist it is qml6glsink for Qt6 while qmlglsink is for Q5

[SGaist]

@JoeCFD good point. The logic of the example still applies though.

There should be a new example for Qt 6 written :-)

[Thanush]

Hi @SGaist , I tried to reuse the code in mine and the build was success but while running it was crashing with an error

Bail out! ERROR:../../main.cpp:35:int main(int, char**): assertion failed: (src && glupload && sink)

[jsulm]

@Thanush So, did you check what is in line 35 in main.cpp?

[Thanush]

@jsulm , Apologies..

        GstElement *pipeline = gst_pipeline_new (NULL);
        GstElement *src = gst_element_factory_make ("videotestsrc", NULL);
        GstElement *glupload = gst_element_factory_make ("glupload", NULL);
        GstElement *sink = gst_element_factory_make ("qmlglsink", NULL);

        **g_assert (src && glupload && sink);**//This line caused the error

        gst_bin_add_many (GST_BIN (pipeline), src, glupload, sink, NULL);
        gst_element_link_many (src, glupload, sink, NULL);

[jsulm]

@Thanush said in Video plays on a new Window while launched through gstreamer in Qt6 qml application:

g_assert (src && glupload && sink);

So, at least one of these 3 failed. You can check which one.

[Thanush]

@Thanush said in Video plays on a new Window while launched through gstreamer in Qt6 qml application:

GstElement *sink = gst_element_factory_make ("qmlglsink", NULL);

This returns a null pointer, I'm not sure why

[Bob64]

I know nothing about this, but wasn't it pointed out above that it should be "qml6glsink"?

[JoeCFD]

@Thanush said in Video plays on a new Window while launched through gstreamer in Qt6 qml application:

qmlglsink

What is your OS? What is your gstreamer version? In order to use qml6glsink(or qmlglsink), you need to install GStreamer Good Plug-in. It is likely that gstreamer good plug-in does not include qml6glsink because it needs qt 6 to be built. In this case, you have to build gstreamer with Qt6 by yourself. The old gstreamer versions do not have qml6glsink.

[Thanush]

@JoeCFD I am using Ubuntu and the gstreamer version is version 1.20.3. I also tried with qml6glsink and qmlglsink and the result is same

[SGaist]

Did you install the GStreamer plugin packages ?

[Thanush]

@SGaist These are the gstreamer packages present in my ubuntu

ii  gir1.2-gstreamer-1.0:amd64                 1.20.3-0ubuntu1                         amd64        GObject introspection data for the GStreamer library
ii  gstreamer1.0-alsa:amd64                    1.20.1-1ubuntu0.1                       amd64        GStreamer plugin for ALSA
ii  gstreamer1.0-clutter-3.0:amd64             3.0.27-2ubuntu1                         amd64        Clutter PLugin for GStreamer 1.0
ii  gstreamer1.0-gl:amd64                      1.20.1-1ubuntu0.1                       amd64        GStreamer plugins for GL
ii  gstreamer1.0-gtk3:amd64                    1.20.3-0ubuntu1.1                       amd64        GStreamer plugin for GTK+3
ii  gstreamer1.0-libav:amd64                   1.20.3-0ubuntu1                         amd64        ffmpeg plugin for GStreamer
ii  gstreamer1.0-packagekit                    1.2.5-2ubuntu2                          amd64        GStreamer plugin to install codecs using PackageKit
ii  gstreamer1.0-pipewire:amd64                0.3.48-1ubuntu3                         amd64        GStreamer 1.0 plugin for the PipeWire multimedia server
ii  gstreamer1.0-plugins-bad:amd64             1.20.3-0ubuntu1.1                       amd64        GStreamer plugins from the "bad" set
ii  gstreamer1.0-plugins-base:amd64            1.20.1-1ubuntu0.1                       amd64        GStreamer plugins from the "base" set
ii  gstreamer1.0-plugins-base-apps             1.20.1-1ubuntu0.1                       amd64        GStreamer helper programs from the "base" set
ii  gstreamer1.0-plugins-good:amd64            1.20.3-0ubuntu1.1                       amd64        GStreamer plugins from the "good" set
ii  gstreamer1.0-plugins-ugly:amd64            1.20.1-1                                amd64        GStreamer plugins from the "ugly" set
ii  gstreamer1.0-pulseaudio:amd64              1.20.3-0ubuntu1.1                       amd64        GStreamer plugin for PulseAudio (transitional package)
ii  gstreamer1.0-tools                         1.20.3-0ubuntu1                         amd64        Tools for use with GStreamer
ii  gstreamer1.0-x:amd64                       1.20.1-1ubuntu0.1                       amd64        GStreamer plugins for X11 and Pango
ii  libgstreamer-gl1.0-0:amd64                 1.20.1-1ubuntu0.1                       amd64        GStreamer GL libraries
ii  libgstreamer-plugins-bad1.0-0:amd64        1.20.3-0ubuntu1.1                       amd64        GStreamer libraries from the "bad" set
ii  libgstreamer-plugins-base1.0-0:amd64       1.20.1-1ubuntu0.1                       amd64        GStreamer libraries from the "base" set
ii  libgstreamer-plugins-base1.0-dev:amd64     1.20.1-1ubuntu0.1                       amd64        GStreamer development files for libraries from the "base" set
ii  libgstreamer-plugins-good1.0-0:amd64       1.20.3-0ubuntu1.1                       amd64        GStreamer development files for libraries from the "good" set
ii  libgstreamer-plugins-good1.0-dev           1.20.3-0ubuntu1.1                       amd64        GStreamer development files for libraries from the "good" set
ii  libgstreamer1.0-0:amd64                    1.20.3-0ubuntu1                         amd64        Core GStreamer libraries and elements
ii  libgstreamer1.0-dev:amd64                  1.20.3-0ubuntu1                         amd64        GStreamer core development files

[Thanush]

@SGaist Hi! Does qmlglsink/qml6glsink support in qt6.7? Because I am getting a qml error

QQmlApplicationEngine failed to load component
qrc:/untitled8/main.qml:4:1: module "org.freedesktop.gstreamer.GstGLQt6VideoItem" is not installed

Once I comment out this line in main.qml, the application is running but no video is displaying.

[SGaist]

@Thanush It's not a Qt 6 issue, it's a GStreamer issue. I think the version you are using is too old and does not contain the class yet.

[Thanush]

Hi @SGaist .So that was the problem? Update the Gstreamer to latest version and this issue would be resolved?

[SGaist]

That would be it, yes.

[Thanush]

Hi @SGaist, I see that the gstreamer version contains the qml6glsink, but after downloading from the https://gstreamer.freedesktop.org/src/gstreamer/ .... but i am not sure how it needs to be configured against the old version of gstreamer present in ubuntu..

[SGaist]

You would have to build the plugin yourself and link against it.