Including external header (gst.h)

[Plox]

Good day fellow programmers,

I am trying to include Gstreamer into my Qt application.
In order to do so I need to include "gst.h".

So far I've tried to simply add it to the main.cpp file.

#include <gst/gst.h>

#include <gst/gst.h>

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I've also tried the direct file path:

#include "/usr/include/gstreamer-1.0/gst/gst.h"

#include "/usr/include/gstreamer-1.0/gst/gst.h"

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I've also tried specifying an INCLUDEPATH in the .pro file:

INCLUDEPATH += /usr/include/gstreamer-1.0/gst

INCLUDEPATH += /usr/include/gstreamer-1.0/gst

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As this didn't work I tried to be a bit more specific:

unix:INCLUDEPATH += /usr/include/gstreamer-1.0/gst

unix:INCLUDEPATH += /usr/include/gstreamer-1.0/gst

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During these tries I've been using the command in main.cpp

#include <gst/gst.h>

#include <gst/gst.h>

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but received the error all the time

/home/finn/GST_Test2/main.cpp:2: error: gst/gst.h: No such file or directory

/home/finn/GST_Test2/main.cpp:2: error: gst/gst.h: No such file or directory

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.

Besides that I also tried using PKGCONFIG:

unix {
   CONFIG += link_pkgconfig
   PKGCONFIG += gstreamer-1.0
}

unix {
   CONFIG += link_pkgconfig
   PKGCONFIG += gstreamer-1.0
}

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According to this commands result gstreamer-1.0 exists on the target system.

pkg-config --list-all | grep gstreamer

pkg-config --list-all | grep gstreamer

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However I always receive the error

:-1: error: Package gstreamer-1.0 not found

:-1: error: Package gstreamer-1.0 not found

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The target system is a Raspberry Pi running Linux Debian. I've been able to successfully build applications on that system which is why I would guess that the target system should not be the problem.

The file gst.h does exist on the target system in the directory /usr/include/gstreamer-1.0/gst

Does anyone has an idea how to properly include gst.h into my Qt project?
Thanks a lot!

Best regards,
Plox

[stampede]

INCLUDEPATH += /usr/include/gstreamer-1.0/gst

but you try to include the header with "gst/gst.h", compiler can't find it because probably there is no "gst" subdir in "/usr/include/gstreamer-1.0/gst" directory.
If the file path is "/usr/include/gstreamer-1.0/gst/gst.h" then you need to add "INCLUDEPATH += /usr/include/gstreamer-1.0/" and include with "gst/gst.h", or "INCLUDEPATH += /usr/include/gstreamer-1.0/gst" and include with #include <gst.h>

[Plox]

Thank you for your answer, stampede.

I modified said code lines.

This is the .pro file:

INCLUDEPATH += /usr/include/gstreamer-1.0/

INCLUDEPATH += /usr/include/gstreamer-1.0/

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And this is the main.cpp:

#include "gst/gst.h"

#include "gst/gst.h"

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Sadly I am still getting the error:

/home/finn/GST_Test2/main.cpp:2: error: gst/gst.h: No such file or directory

/home/finn/GST_Test2/main.cpp:2: error: gst/gst.h: No such file or directory

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Why does this error still occur?

Thanks a lot!

[stampede]

gstreamer-1.0 exists on the target system

By "target system" you mean the system on which you want to deploy your app, or the machine where you are trying to build the app ? I'm just confused about the term "target system".
This file should be present on the build machine. Does it exist on your computer (the one where you are developing the app) ?

[Plox]

I am developing my app on a desktop pc running Ubuntu for a Raspberry Pi running Debian.
The file I want to include only exists on the Raspberry.

Do I need to copy it onto the Ubuntu machine in order to use it, although it's functionality is only going to be used on the Raspberry?

[stampede]

Yes, your compiler needs to have access to all the headers and libraries in order to build your application. Make sure to install the gstreamer package in development version.

[Plox]

Allright, thanks a lot for your help, I greatly appreciate it!

One last question: What is the difference between the regular gstreamer version and dev version?

[stampede]

Regular version doesn't include headers required for developing applications using gstreamer, only shared libraries:
file list for regular libgstreamer
file list for libgstreamer-dev

[Plox]

I am afraid that I'll need help in another matter regarding this development step too.

I've installed gstreamer on the Ubuntu machine, set the proper INCLUDEPATH and included gst.h into main.cpp.
A look into the file system confirms that gstreamer has been successfully installed as all header files seem to be present.

After resolving some issues regarding glib all dependencies seem to be sorted out, however I am experiencing an error as soon as I try to actually call functions from gst.h.

This is the error I receive:

undefined reference to 'gst_init'

undefined reference to 'gst_init'

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As I am receiving this error for every gst.h function I reduced main.cpp to only include gst_init.

#include <QtCore/QCoreApplication>
          #include <gst/gst.h>
 
           int main(int argc, char *argv[]){
           QCoreApplication a(argc, argv);
 
           gst_init (NULL,NULL);
           return a.exec();
           }

#include <QtCore/QCoreApplication>
          #include <gst/gst.h>
           
           int main(int argc, char *argv[]){
           QCoreApplication a(argc, argv);
 
           gst_init (NULL,NULL);
           return a.exec();
           }

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The file gst.h is where it's supposed to be and based on the fact that Creator even suggests "gst_init" once I type e.g "gst" into main.cpp and since the function "gst_init" is underlayed with that typical grey box I think that gst.h has been successfully included into this project.

Why do I still receive such error messages?

Thanks a lot for your help!

[stampede]

"Undefined reference ..." is a linker error, you need to add library path and link to gst libraries, in .pro file:

LIBS += -L /path/to/gstreamer/libraries
LIBS += <gstreamer cflags>

I dont know what are the parameters exactly, try "pkg-config --cflags --libs gstreamer-1.0" to get the values.
btw. I think you will find some useful informations here

[Plox]

That makes sense. This will be the first thing to be tried out tomorrow morning.

Thank you for your help, this really made my day.