QCamera Problems!

mranger90

If you are running from a VMware machine, you could have problems accessing the camera.
Make sure that the camera is not connected to the host.
See the "Player | Removable Devices | ..." menu option of VMware player.
Also, if its connect to the usb you may have to downgrade from usb3.0 to sub 2.0 or even usb 1.1 from the player settings menu.

Hasan Vaez

@mranger90
Thank you, but I think you do not read my full description in the top.
I tested it in another PC without VM.

mrjj

@Hasan-Vaez said in QCamera Problems!:

Unable to query the parameter info: "Invalid argument"

Google that suggest something with the gstreamer. but im not 100% sure.

Anyway, i would test the camera in the same linux using some linux camera program to verify something can see it.
https://www.linuxlinks.com/webcam/

Hasan Vaez

Just tell me, you do not having any problem with Camera with QT C++ in linux?

mranger90

I've been able to use it many time with various Linuxi and through several Qt releases.
Are you able to use the camera outside of Qt, for example with the Cheese app ?

Hasan Vaez

@mranger90
Thank you for your reply.
Yes, I can use it outside of QT. I tested it with Cheese app in Ubuntu 16.04 LTS without any problem.
I also have not any problem in other OS like MAC and WINDOWS.

Hasan Vaez

@mranger90
Please tell me what plugins did you install for qmultimedia in QT5?

mranger90

Unfortunately I don't have any of those systems in front of me now and won't until Monday.
Off the top of my head I'm pretty sure I've installed libgstreamerdev and maybe gstpluginsbase?
Not sure of the exact package names.

mranger90

Ok, I just set up an Ubuntu 16.04 VM with VMWare on my pathetically underpowered home system which is running Win 10 as the native OS.
Installed Qt 5.10.0.
Have a Microsoft LifeCam HD-600 usb camera.
VMWare is set up to use USB 1.1.
Cheese can access and display the camera.
To build the Examples/multimediaWidgets/camera project I had to install:
libgl-mesa-dev
mesa-common-dev
libpulse-dev

Other than a little fiddling with the camera parameters that's all I had to do to get it to work on a stock ubuntu 16.04 install.
I'd have to dig out some of my other apps to test with, but it looks like this should work for you. If you can post a more complete set of your code I'd be happy to test it tomorrow.

Hasan Vaez

@mranger90 said in QCamera Problems!:

libpulse-dev

Thank you arranger for your comments.
I install another Ubuntu 16.04, Qt5.10.0 (along with 3 components: libgl1-mesa-dev mesa-common-dev libpulse-dev)
Test the Camera example with VMWARE MAC CAM and also with LOGITEC CAM.

The problem remained!

My codes are:
1- Camera example in QT folder
2- The following simple codes:

QCamera *Camera;
QCameraImageCapture *ImageCapture;
QCameraInfo *CameraInfo;

void MainWindow::on_pushButton_clicked()
{
Camera = new QCamera;
ImageCapture = new QCameraImageCapture(Camera);

Camera->setViewfinder(ui->wCamera);
ui->wCamera->setAspectRatioMode(Qt::KeepAspectRatioByExpanding);
Camera->setCaptureMode(QCamera::CaptureViewfinder);
Camera->start();
}

All things seems to be correct, there should be a small point which I don't know what is it??

mranger90

ok, Heres the simplest code I could create that runs with my setup:
Mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QCamera>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

private slots:
    void on_actionStart_triggered();

private:
    Ui::MainWindow *ui;
    QCamera *m_camera;
};

#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QVideoWidget>
#include <QCameraInfo>
#include <QCameraViewfinderSettings>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QVideoWidget *videoDisplay = new QVideoWidget;
    setCentralWidget(videoDisplay);

    // get a list of available cameras
    QList<QCameraInfo> cameras = QCameraInfo::availableCameras();
    // just pick the first
    if (cameras.size() > 0) {
        qDebug() << "creating camera from " << cameras.at(0).deviceName() << cameras.at(0).description();
        m_camera = new QCamera(cameras.at(0));
        if (m_camera) {
            m_camera->setViewfinder(videoDisplay);
            m_camera->setCaptureMode(QCamera::CaptureViewfinder);
            QCameraViewfinderSettings settings = m_camera->viewfinderSettings();
            // change resolution to 320x240
            settings.setResolution(QSize(320,240));
            m_camera->setViewfinderSettings(settings);


        }
    }
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::on_actionStart_triggered()
{
    if (m_camera) {
        m_camera->start();
    }
}

camtest.pro


QT       += core gui multimedia multimediawidgets

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = camtest
TEMPLATE = app

DEFINES += QT_DEPRECATED_WARNINGS
SOURCES += \
        main.cpp \
        mainwindow.cpp

HEADERS += \
        mainwindow.h

FORMS += \
        mainwindow.ui

Mainwindow is just a stock MainWindow with a menu item to start video capture.

Let me know if this works.

Hasan Vaez

@mranger90
Thank you for for taking these times.
I think I found the problem.

Camera sources uses some codes which is not compatible with some old camera and also with VMWare cams, as it uses some parameters which can not be found in old cams and VMware cams.

VMWare cameras use USB 2.0 and 3.0 and can not set as USB 1.1.

QCamera has high probability problem with VMWare and also with Cameras with USB 1.1!

The finial test is to purchase a new Cam and test it in Linux.

I think this problem comes from Hardware and all of my configs are set OK.

If the problem become solved by changing a new Cam I should report it as s bug, Cuz some users use their QT written programs in VMWare machines.

Would you please tell me whether you test your codes in VMWare or not?

Thank and regards.

mranger90

Yes, I set this up in a VMWare 12 player last night.
Actually, it is very system and camera dependent.
For instance, on my low powered home system I MUST set VMWare to use USB 1.1
or there will be problems. That is the camera is recognized but not video will be displayed.
Also, due to the low capabilities of my system, I do not get a valid display unless the camera is set to 320x240.
I really don't believe this is a Qt issue because so much is dependent on the underlying system capabilities, both in hardware and software. Perhaps if you play around with the QViewFinder settings, you may find a combination that works.

Hasan Vaez

@mranger90
Agree, I have tested in windows and the video does not work.

gfxx

Sorrry ... I see these olt post only now .... because try to work my app on my hystorical pc with intel I5 4th gen, ubuntu 16.04 update every mouth .... normally for camera pourpuse I use an other pc with ubuntu 16.04 and work well .... these historical pc actually not work with camera.cpp example provided for QT5.10 .... In these pc there are v4l gstreamer mesa opencv etc etc all updated to recent version .... in the past I used modified by me libv4l.so version (or similar one) and my opencv app work on these pc. But I suppose that modified version is updated and rewrite now from software center updater.

Any how ... there are another problem similar to your ... and the problem generally become from firmware of camera not from SO. In the past i modified v4l lib because the firmware of camera was not "standard".

regards
Giorgio