why Qt can't find 3rd-party libs?

r3d9u11

Hello.
I have Qt5 installed to:

/home/Qt/5.12.7

I also installed 3rd-party packages QtGstreamer to system libs directory:

ldconfig -p | grep libQt5QmlModels
        libQt5QmlModels.so.5 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libQt5QmlModels.so.5
        libQt5QmlModels.so (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libQt5QmlModels.so

Why Qt is trying to find libraries only in it's own installation path?

/home/Qt/5.12.7/gcc_64/lib/libQt5QmlModels.so: No such file or directory

pkg-config output:

pkg-config --cflags Qt5GStreamerQuick-1.0
-DQT_QUICK_LIB -DQT_GUI_LIB -DQT_QMLMODELS_LIB -DQT_QML_LIB -DQT_NETWORK_LIB -pthread -DQT_CORE_LIB -I/usr/include/Qt5GStreamer -I/usr/include/x86_64-linux-gnu/qt5/QtQuick -I/usr/include/x86_64-linux-gnu/qt5 -I/usr/include/x86_64-linux-gnu/qt5/QtGui -I/usr/include/x86_64-linux-gnu/qt5 -I/usr/include/x86_64-linux-gnu/qt5/QtQmlModels -I/usr/include/x86_64-linux-gnu/qt5 -I/usr/include/x86_64-linux-gnu/qt5/QtQml -I/usr/include/x86_64-linux-gnu/qt5 -I/usr/include/x86_64-linux-gnu/qt5/QtNetwork -I/usr/include/x86_64-linux-gnu/qt5 -I/usr/include/Qt5GStreamer -I/usr/include/gstreamer-1.0 -I/usr/include/orc-0.4 -I/usr/include/gstreamer-1.0 -I/usr/include/Qt5GStreamer -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/x86_64-linux-gnu/qt5/QtCore -I/usr/include/x86_64-linux-gnu/qt5

and

pkg-config --libs Qt5GStreamerQuick-1.0
-lQt5GStreamerQuick-1.0 -lQt5Quick -lQt5Gui -lQt5QmlModels -lQt5Qml -lQt5Network -lQt5GStreamer-1.0 -lQt5GLib-2.0 -lQt5Core

I've tried to add something like:

LIBS += -L"/usr/lib/x86_64-linux-gnu" -lQt5QmlModels

but it doesn't help.

How to force Qt to find needed libs also in "global" storage?
Thanks!

r3d9u11

@jsulm , @SGaist Thank you all for your useful hints!

Now I've got success without qt-gstreamer wrapper:
https://gstreamer.freedesktop.org/documentation/video/gstvideooverlay.html?gi-language=c
(manual a bit outdated, but works).

jsulm

@r3d9u11 said in why Qt can't find 3rd-party libs?:

I also installed 3rd-party packages QtGstreamer to system libs directory

For Qt 5.12.7? And why in system lib directory?

r3d9u11

@jsulm
Yes, for Qt 5.12.7, which was installed through Qt's own installer.

And why in system lib directory?

Because I just installed linux-package, which contains needed headers and libraries.

jsulm

@r3d9u11 said in why Qt can't find 3rd-party libs?:

Because I just installed linux-package

And this package was built using Qt 5.12.7?

r3d9u11

@jsulm I don't think exactly 5.12.7

jsulm

@r3d9u11 said in why Qt can't find 3rd-party libs?:

I don't think exactly 5.12.7

That could be the problem

SGaist

Hi,

First this: QtStreamer is not an official Qt package.

It has also been declared deprecated and unmaintained. Depending on what you want to accomplish they have now a plugin for QML in one of the GStreamer plugin packages. Still depending on what you want to do, if your Qt version is new enough, you can use custom pipelines in QtMultiMedia.

If you still want to use it, you will likely have less trouble using your distribution provided Qt against which that module was built.

r3d9u11

@SGaist Well, I want to record Qt-window to file.
I've found some examples, but olnly for qt-gstreamer. I didn't know that it is outdated.

With QtMultimedia there is no any way to do that (I asked that question before), it able only to read incoming video stream and render it, as I understand right.

So I should to create gstreamer's pipline manually.

r3d9u11

@jsulm , @SGaist Thank you all for your useful hints!

Now I've got success without qt-gstreamer wrapper:
https://gstreamer.freedesktop.org/documentation/video/gstvideooverlay.html?gi-language=c
(manual a bit outdated, but works).

SGaist

Thanks for the feedback !