How to get QCamera to work?

[feraudyh]

I want to use QCamera, but the page on QCamera does not say how I must change my project file to use it.
I've got QT += multimedia multimediawidgets
but this appears to be insufficient.
It seems to me that for every class the doc hould mention this kind of detail.

Added after 18 minutes:

It seems now that i just had to wait several minutes before QtCreator woke up to the fact that I had added
QT += multimedia multimediawidgets
to the project file
and now "magically"
#include <QCameraViewfinder>
#include <QCamera>
are no longer underlined in green.

problem solved, but my remark about the doc still holds.

[ChrisW67]

Get into the habit of running qmake after you modify a PRO file.

The modification required to the PRO file is documented at the module level.
Qt Multimedia (http://qt-project.org/doc/qt-5.0/qtmultimedia/qtmultimedia-index.html)

[feraudyh]

Hi,
I've used QCamera on Windows, now I'd like to port my stuff to Linux.
I downloaded Qt 5.2.1 on XUbuntu, and I've got a message saying QCamera cannot be found (when I try to #include <QCamera>)
Does anyone know if QCamera is planned, or do I just need to download some extensions?

[feraudyh]

It seems that the QtCreator 3.0.1 + Qt 5.2.1 does not support QCamera on Xubuntu.
Any workarounds? Any plans for it to be released in the near future?
Furthermore the MultimediaWidgets module is rejected by qmake.

[stampede]

QCamera worked for me on Linux Mint (latest release) with gstreamer backend - I can't remember exactly, but I think I had to install the "bad" plugins set (gst-plugins-bad) and build the QCamera gstreamer plugin from source ("qtmultimedia\src\plugins\gstreamer\camerabin"). I didn't care about the audio, so I can't really help you with that.
Anyway, every camera I tested supported only one basic capture mode (typically 800x600@20 fps), without the possibility to change it, even if hardware supports much bigger resolutions / framerates.

[pratik.manvar]

Hi,

I am having problem in recording video using QMediaRecorder and QCamera classes.
My application crashes with segmentation fault when trying to start camera ("camera->start" in code).

Below is code, i have written. Please guide me out here, if have i am missing something. Thanks in advance.


/************************************************** ********************/
QMediaRecorder *recorder;
QCamera *camera;
QCameraViewfinder *viewfinder;

QCameraInfo cameraInfo(camera);
QList<QCameraInfo> cameras = QCameraInfo::availableCameras();
foreach (cameraInfo, cameras)
qDebug() << cameraInfo.deviceName();

camera = new QCamera(cameraInfo);

viewfinder = new QCameraViewfinder();
camera->setViewfinder(viewfinder);
setCentralWidget(viewfinder);
viewfinder->show();

if(true == isCaptureModeSupported(QCamera::CaptureVideo)
{
camera->setCaptureMode(QCamera::CaptureVideo);
}

recorder = new QMediaRecorder(camera);
camera->start();

recorder->setOutputLocation(QUrl::fromLocalFile("record.mp4"));
recorder->record();

/************************************************** ********************/

[d_stranz]

Where is this code? In a MainWindow constructor? In the constructor, the MainWindow (and all of its children) are not yet visible and do not have valid sizes. This could be part of the problem - that you are telling the camera to start displaying on a viewfinder window that has not been fully initialized. You are also starting the camera before you have told the recorder where to write its output. Calling "viewfinder->show()" in the constructor is a waste of time. It will be shown when the MainWindow is shown, and that does not happen until the showEvent().

I would suggest that you implement a showEvent() handler for the MainWindow and move the camera->start() call there. All of the other setup can probably remain where it is. You will need to make the camera instance a member variable of the MainWindow class if it is not already.

And use CODE tags when posting source code.

[pratik.manvar]

Hello d_stranz,

Thanks for your reply.

The code is not in constructor, there is a push-button to start recording.

Here with i have attached files of my code. Thanks for the knowledge for pasting source code:).

[bilal mohamed]

can you please add the ui.mainwindow file

[d_stranz]

You don't really need the specific file for this project. All the poster did was to make the QCameraViewFinder the central widget for a generic MainWindow. Just create a new project, and copy the mainwindow.ui fle from that.

The last posts from this poster were these, in 2016, and it is very unlikely he is still following this forum.