Client for VNC video streaming

[mrjj]

@LeLev
Hi
Yes, SGaist was so kind to dig one up. :) (see link higher up)
Its not part of official Qt but Qt never the less.
Its from 2016 so seems pretty recent.
So the biggest issue will be to produce a video from the frames. Preferable compressed
if video size matters.

[ODБOï]

@mrjj said in Client for VNC video streaming:

see link higher

cant find it,

https://bitbucket.org/amahta/qvncclient/src ?

[mrjj]

@LeLev
yep :)

[ODБOï]

@mrjj
perfect ! thank you and thank you @SGaist

[ODБOï]

@SGaist said in Client for VNC video streaming:

This article and the linked repository might be just what you need

omg.. sorry i did not see your messages. my bad.
Thank you very much

[SGaist]

No worries ;-)

[ODБOï]

@mrjj said in Client for VNC video streaming:

How many FPS do you need to record

Hi,
So finally, thaks to you and SGaist the server is running on the machine i want to connect,
on the other side, i have my QVNCClientWidget that connects and shows the first machine GUI.

Now, i need to record the screen.

I simply added my signal ' void saveImg(QImage );' to **QVNCClientWidget **,
that signal is emited in QVNCClientWidget::paintEvent

i'm passing the screen images to a slot that will save them as simple images.

void QVNCClientWidget::paintEvent(QPaintEvent *)
{
    if(screen.isNull())
    {
        screen = QImage(width(), height(), QImage::Format_RGB32);
        screen.fill(Qt::red);

    }

     emit saveImg(screen); 

    QPainter painter;
    painter.begin(this);
    painter.drawImage(0, 0, screen.scaled(width(), height(), Qt::IgnoreAspectRatio, Qt::SmoothTransformation));
    painter.end();
}

So, for now i'm only recording all the frames as .png images, and then i can reconstruct a video with a 3rd party tool (VirtualDub).
To reconstruct a video my tool needs a parameter FPS (and it must match with my program FPS , if not, video is to fast or to slow)
Is there a way to specify the FPS with QVNCClientWidget ?

Or do you see a solution to create the video with the images directly in my qt app ? I read its possible with LibAvi or Opencv but can't find Qt only solution.

Thank you

[SGaist]

One thing you could do is use GStreamer to connect to your VNC server and record the video.

See the rfbsrc plugin.

[ODБOï]

@SGaist
thank you very much, i will try that. But do you mean i no more need the QVNCClientWidget ? or i need to integrate GStreamer with my widget ?
I wanted to create my qt application client to have control on it : automatically stop/start recording/ delete when on some conditions is meet etc...
THX!

[SGaist]

The idea is that you can use your widget for looking at whatever you need and GStreamer for the recording part which will allow you to generate a video file directly and not put a heavy load on your GUI thread.

[ODБOï]

@SGaist
i don't need to look the screen i don't want gui, i only need the record part.

[SGaist]

In that case, using GStreamer would simplify the process of creating the video especially at the speed of the stream you get.

[ODБOï]

hi,
@SGaist said in Client for VNC video streaming:

simplify

how to use it please? I want to build GStreamer with this forum article help
but the link is down : https://cgit.freedesktop.org/gstreamer/qt-gstreamer
https://gitlab.freedesktop.org/gstreamer/qt-gstreamerSource download/src/qt-gstreamer

[SGaist]

The link is back up however, the bindings should be considered outdated.

Since you won't be looking at the the stream itself, what you can do is use the gstreamer API directly.

Use the command line to find the best pipeline for your needs and then you can use something like GstParse to generate the pipeline in your code and then start it.

[ODБOï]

Hi @SGaist

Please tell me what command line are you talking about, I'm reading some introduction to GStreamer because ive never heared about it. What is the pipeline ? Thank you for the links, i'm looking for more general introduction/tutorial documents

What are the drawbacks of my current solution please ? : Connecting with QVNCClientWidget, and then saving an image every time Gui is refreshed, i get 15 fps and it's enough for me.

Thank you very mush for the help

[SGaist]

gst-launch-1.0 is the tool

The drawback is as you wrote, you have to build the video afterwards and you don't really know the frame rate of it.

[ODБOï]

@SGaist hello,

I installed gstreamer-1.0-devel-x86_64-1.14.3
(I dit not built it)
and linked my app against it adding this in my .pro

INCLUDEPATH += c:/gstreamer/1.0/x86_64/include \
        c:/gstreamer/1.0/x86_64/lib/gstreamer-1.0/include \
        c:/gstreamer/1.0/x86_64/include/gstreamer-1.0 \
        c:/gstreamer/1.0/x86_64/include/glib-2.0\
        c:/gstreamer/1.0/x86_64/include/glib-2.0/glib \
        c:/gstreamer/1.0/x86_64/lib/glib-2.0/include

LIBS += -Lc:/gstreamer/1.0/x86_64/lib
LIBS +=  -lgstreamer-1.0 -lglib-2.0 -lwinpthread -lgobject-2.0 -lgmodule-2.0 -lgthread-2.0
CONFIG += c:/gstreamer/1.0/x86_64/lib/pkgconfig

My app will compile but crash as soon i run it and gst_init(&argc, &argv) is called...
I can't even put breakpoints, debuggings stops immediately

#include "mainwindow.h"
#include <QApplication>
#include <gst/gst.h>
#include <QDebug>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.showMaximized();
    GstElement *pipeline;
    GstBus *bus;
    GstMessage *msg;
    putenv("GST_PLUGIN_PATH=C:\\gstreamer\\1.0\\x86_64\\lib\\gstreamer-1.0\\");
    gst_init(&argc, &argv); // << crash
    return a.exec();
    }

Could you please tell me if you see something ?
Thank you for help

[SGaist]

I would try calling get_init before creating the QApplication object.

[ODБOï]

@SGaist thx
but i have the same issue when i call gst_Init() before creating QApplication object.

int main(int argc, char *argv[])
{
    putenv("GST_PLUGIN_PATH=C:\\gstreamer\\1.0\\x86_64\\lib\\gstreamer-1.0\\");
    gst_init(&argc, &argv); // << crash

    QApplication a(argc, argv);
    MainWindow w;
    w.showMaximized();
...

The only output i get is :

11:52:22: The process was ended forcefully.
11:52:22: C:/Users/lev/Documents/build-QVNCClient-Desktop_Qt_5_12_0_MinGW_64_bit-Release/release/QVNCClient crashed.

i tryed to see more information about the crash in Windows event viewer but nothing is reported there

Windows 7
Qt5.12
GNU Make 4.2.1 built for x86_64-w64-mingw32

[SGaist]

Did you add the path to where the gstreamer dlls can be found to the PATH environment variable ? This should be done in the Run part of the Project panel.