Qt and gstreamer

stephane78 0

Hi I have made a program based on the example of gstreamer-1.0 "GstOverlay and Qt" but the video is not displayed in my widget
I play the same video with the same pipeline with gst-launch but in my program with Qt the video is not displayed (Qt5.12.3 and gstreamer 1.10 )
I think my .pro is not correct :

#-------------------------------------------------
#
# Project created by QtCreator 2017-11-06T21:33:02
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = gst01
TEMPLATE = app
INCLUDEPATH +="/usr/include"
INCLUDEPATH +="/usr/include/glib-2.0"
INCLUDEPATH +="/usr/include/gstreamer-1.0"
CONFIG += link_pkgconfig
PKGCONFIG += gstreamer-1.0
PKGCONFIG += gstreamer-video-1.0
# The following define makes your compiler emit warnings if you use
# any feature of Qt which as been marked as deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if you use deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
LIBS+=-L"/usr/lib/x86_64-linux-gnu/gstreamer-1.0" -lgstxvimagesink -L"/usr/lib/x86_64-linux-gnu" -lgstbase-1.0 -lgstreamer-1.0 -lglib-2.0 -lgobject-2.0

SOURCES += main.cpp\
        mainwindow.cpp

HEADERS  += mainwindow.h

FORMS    += mainwindow.ui

my pipeline is filesrc and decodebin and xvimagesink and my code is like the exemple here : GstVideoOverlay

can someone help me ?

SGaist

Hi,

What Linux distribution are you running ?
What Desktop Environment are you using ?
What window manager are you using ?

stephane78 0

@SGaist Hi, I was (at home) on my debian 9 with kde5 plasma but I should try too on centOs (because the target is RHEL).I can display my video with gst-launch but not with my program

raven-worx

@stephane78-0
since you are using gstreamer-1.0, did you also compile Qt with gstreamer-1.0 support? AFAIK it uses gstreamer-0.1 by default

stephane78 0

@raven-worx Hi thank you,no I didn't compile Qt with gstreamer 1.0 support but do you think I need this ? because I use only a QWidget and the winId handle of the QWidget , here is my code :```

#include <glib.h>
#include <gst/gst.h>
#include <gst/video/videooverlay.h>

#include <QApplication>
#include <QTimer>
#include <QWidget>

int main(int argc, char *argv[])
{
if (!g_thread_supported ())
g_thread_init (NULL);

gst_init (&argc, &argv);
QApplication app(argc, argv);
//MainWindow w;
QWidget w;
w.resize(640,480);

app.connect(&app, SIGNAL(lastWindowClosed()), &app, SLOT(quit ()));

// prepare the pipeline

GstElement *pipeline = gst_pipeline_new ("xvoverlay");
GstElement *videosrc = gst_element_factory_make ("filesrc","videosrc");
GstElement *videoscale=gst_element_factory_make("videoscale",NULL);
GstElement *capsfilter=gst_element_factory_make("capsfilter",NULL);
GstElement *sink = gst_element_factory_make ("xvimagesink", NULL);
GstElement *decodebin = gst_element_factory_make("decodebin", NULL);

//g_object_set (G_OBJECT(playbin),"uri","file:///home/user/Downloads/thesimpsonstrailer.mp4");
g_object_set (G_OBJECT (videosrc), "location", "/home/user/Downloads/small.mp4", NULL);
GstCaps *caps = gst_caps_new_simple ("video/x-raw",
"format", G_TYPE_STRING, "RGB",
"framerate", GST_TYPE_FRACTION, 25, 1,
"width", G_TYPE_INT, 640,
"height", G_TYPE_INT, 480,NULL);

g_object_set(G_OBJECT(capsfilter), "caps", caps, NULL);
gst_caps_unref (caps);
gst_bin_add_many (GST_BIN (pipeline), videosrc, decodebin, sink, NULL);
gst_element_link_many(videosrc, decodebin, NULL);
gst_element_link_many(decodebin, sink, NULL);

// prepare the ui

w.show();

gst_element_set_state(sink, GST_STATE_READY);
WId xwinid =w.winId();
gst_video_overlay_set_window_handle (GST_VIDEO_OVERLAY (sink), xwinid);

// run the pipeline

GstStateChangeReturn sret = gst_element_set_state (pipeline,
GST_STATE_PLAYING);
if (sret == GST_STATE_CHANGE_FAILURE)
{
gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);
// Exit application
QTimer::singleShot(0, QApplication::activeWindow(), SLOT(quit()));
}

int ret = app.exec();

w.hide();

gst_element_set_state (pipeline, GST_STATE_NULL);
gst_object_unref (pipeline);

return ret;
}

raven-worx

@stephane78-0
oh sry...i thought you are talking about the QtMultimedia module

stephane78 0

@raven-worx Hi ,you have perhaps a good idea I will try to compile Qt with gstreamer 1.0 support and I come again back

SGaist

Did you check the winID value ?

stephane78 0

@SGaist Hi,yes xwinId=228589573

stephane78 0

Hi, I have tryed another method with the plugin qmlsink s owith qml but I have a black screen, my code comes from an exemple of the plugin good on github:

int main(int argc, char *argv[])
{
  int ret;

  gst_init (&argc, &argv);

  {
    QGuiApplication app(argc, argv);

    GstElement *pipeline = gst_pipeline_new (NULL);
    //GstElement *src = gst_element_factory_make ("videotestsrc", NULL);
    GstElement *src = gst_element_factory_make ("filesrc","videosrc");
    GstElement *glupload = gst_element_factory_make ("glupload", NULL);
    GstElement *decodebin = gst_element_factory_make("decodebin", NULL);
    /* the plugin must be loaded before loading the qml file to register the
     * GstGLVideoItem qml item */
    GstElement *sink = gst_element_factory_make ("qmlglsink", NULL);

    g_assert (src && glupload && sink);
    g_object_set (G_OBJECT (src), "location", "/home/user/Downloads/small.mp4", NULL);
    gst_bin_add_many (GST_BIN (pipeline), src, decodebin, glupload, sink, NULL);
    gst_element_link_many (src, decodebin, glupload, sink, NULL);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    QQuickItem *videoItem;
    QQuickWindow *rootObject;

    /* find and set the videoItem on the sink */
    rootObject = static_cast<QQuickWindow *> (engine.rootObjects().first());
    videoItem = rootObject->findChild<QQuickItem *> ("videoItem");
    g_assert (videoItem);
    g_object_set(sink, "widget", videoItem, NULL);

    rootObject->scheduleRenderJob (new SetPlaying (pipeline),
        QQuickWindow::BeforeSynchronizingStage);

    ret = app.exec();

    gst_element_set_state (pipeline, GST_STATE_NULL);
    gst_object_unref (pipeline);
  }

  gst_deinit ();

  return ret;

so there is perhaps a problem with my debian 9 or it lacks a library

SGaist

Do you get any error message on the console ?

stephane78 0

@SGaist No there isn't any error message in the console

SGaist

Does it work if you follow GStreamer's Qt example ?

stephane78 0

@SGaist I will try it,because I have modified it to have as source my video.so I will try the example not modified and come here again.

stephane78 0

@SGaist the example without my modifications runs well.so there is something with my filesrc.but I can play my video with gstlaunch and decodebin and xvimagesink.

SGaist

Then I would gradually modify the example until it does play the file you are trying to play with your code.

PeTroVic

Hey @SGaist and @stephane78-0 ,
Did anyone managed to run that example with "filesrc" instead of "videotestsrc" ?

This example works for me, but it uses "videotestsrc" as Source, but I would like to use "filesrc".
Because, I want to be able to use a custom video.

I'm guessing that I need help with GStreamer, and not QT necessarily. But it's worth taking a shot.

RajReddy

you can try:

    MediaPlayer{
        id: playVideo
        source: "gst-pipeline: filesrc location=/home/root/skim-debris.mp4 ! qtdemux ! avdec_h264 ! qtvideosink"
        autoLoad: true
        autoPlay: true
        playbackRate: 1.0
        loops: 10
    }

    VideoOutput {
        anchors.fill: parent
        source: playVideo
    }