Camera fails when i try to start it

guilherme andrade

I'm trying to create a simple project that lets me use a usb camera, but i'm gettinh an error from gsstreamer and not able to start my camera.
Code:

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QCamera>
#include <QCameraImageCapture>
#include <QCameraViewfinder>
#include <QVBoxLayout>
#include <QMenu>
#include <QAction>
#include <QFileDialog>
#include <QCameraInfo>
#include <QDebug>
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QList<QCameraInfo> cameras = QCameraInfo::availableCameras();
    QCameraInfo desiredCamera;
    for (const QCameraInfo& cameraInfo : cameras) {
            qDebug() << cameraInfo.description();
            if (cameraInfo.description() == "GENERAL - UVC : GENERAL - UVC ") {
                desiredCamera = cameraInfo;
                //break;
            }
        }

    mcamera = new QCamera(desiredCamera);

    mCameraViewfinder =new QCameraViewfinder(this);
    mCameraImageCapture = new QCameraImageCapture(mcamera, this);
    mLayout = new QVBoxLayout;
    mOptionMenu = new QMenu("Options", this);
    mLigarAction = new QAction("Ligar", this);
    mDesligarAction = new QAction("Desligar", this);
    mCaptureAction = new QAction("Capturar", this);

    mOptionMenu->addActions({mLigarAction,mDesligarAction,mCaptureAction});
    ui->option_pn->setMenu(mOptionMenu);
    mcamera->setViewfinder(mCameraViewfinder);
    mLayout->addWidget(mCameraViewfinder);
    mLayout->setMargin(0);
    ui->scrollArea->setLayout(mLayout);

    connect(mLigarAction, &QAction::triggered, [&]() {
        mcamera->start();
    });
    connect(mDesligarAction, &QAction::triggered, [&]() {
        mcamera->stop();
    });
    connect(mCaptureAction, &QAction::triggered, [&]() {
        auto filename = QFileDialog::getSaveFileName(this,"Capturar", "/", "Imagem (*.jpg;*.jpeg)");
        if(filename.isEmpty()){
            return;
        }
        mCameraImageCapture->setCaptureDestination(QCameraImageCapture::CaptureToFile);
        QImageEncoderSettings imageEcoderSettings;
        imageEcoderSettings.setCodec("image/jpeg");
        imageEcoderSettings.setResolution(1600,1200);
        mCameraImageCapture->setEncodingSettings(imageEcoderSettings);
        mcamera->setCaptureMode(QCamera::CaptureStillImage);
        mcamera->start();
        mcamera->searchAndLock();
        mCameraImageCapture->capture(filename);
       mcamera->unlock();

    });

//https://forum.qt.io/topic/127481/gstreamer-critical-error-with-qcamera/3
}

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



The error i'm getting:

Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.
"Integrated_Webcam_HD: Integrate"
"GENERAL - UVC : GENERAL - UVC "

(teste1:63195): GStreamer-CRITICAL **: 17:19:55.647: gst_pad_get_current_caps: assertion 'GST_IS_PAD (pad)' failed

(teste1:63195): GLib-GObject-CRITICAL **: 17:19:55.647: g_object_set: assertion 'G_IS_OBJECT (object)' failed

(teste1:63195): GLib-GObject-CRITICAL **: 17:19:55.647: g_object_set: assertion 'G_IS_OBJECT (object)' failed
CameraBin error: "GStreamer error: negotiation problem."
Unable to query the parameter info: QCameraImageProcessingControl::WhiteBalancePreset : "Invalid argument"
Unable to query the parameter info: QCameraImageProcessingControl::ColorTemperature : "Invalid argument"
CameraBin error: "Internal data stream error."