A camera problem.

[SGaist]

Hi,

Unless you configure the capture to capture to file, its just going to be in the buffer. You can still save it yourself though.

[jenya7]

@SGaist said in A camera problem.:

Hi,

Unless you configure the capture to capture to file, its just going to be in the buffer. You can still save it yourself though.

How do I do that? I see m_imageCapture but no property or method to set a path to a file.
And where the buffer located?

[SGaist]

The buffer just means it's in memory. You'll get a frame to process and then it's up to you to save it.

[jenya7]

@SGaist said in A camera problem.:

The buffer just means it's in memory. You'll get a frame to process and then it's up to you to save it.

After

g_camera.SetCaptureMode(QCamera::CaptureMode::CaptureStillImage);
g_camera.takeImage();

Nothing happens. I didn't get to

void Camera::processCapturedImage(int requestId, const QImage& img)

or

void Camera::imageSaved(int id, const QString &fileName)

How do I know where is the image (if it was taken at all)?

[jsulm]

@jenya7 Did you connect a slot to https://doc.qt.io/qt-5/qcamera.html#errorOccurred to see whether you get any errors? Same for https://doc.qt.io/qt-5/qcameraimagecapture.html#error-1
You can get the cptured image using this signal: https://doc.qt.io/qt-5/qcameraimagecapture.html#imageAvailable

[jenya7]

@jsulm said in A camera problem.:

@jenya7 Did you connect a slot to https://doc.qt.io/qt-5/qcamera.html#errorOccurred to see whether you get any errors? Same for https://doc.qt.io/qt-5/qcameraimagecapture.html#error-1
You can get the cptured image using this signal: https://doc.qt.io/qt-5/qcameraimagecapture.html#imageAvailable

this is what I have

connect(m_imageCapture.data(), &QCameraImageCapture::readyForCaptureChanged, this, &Camera::readyForCapture);
connect(m_imageCapture.data(), &QCameraImageCapture::imageCaptured, this, &Camera::processCapturedImage);
connect(m_imageCapture.data(), &QCameraImageCapture::imageSaved, this, &Camera::imageSaved);
connect(m_imageCapture.data(), QOverload<int, QCameraImageCapture::Error, const QString &>::of(&QCameraImageCapture::error),
            this, &Camera::displayCaptureError);

[jsulm]

@jenya7 So, what about trying https://doc.qt.io/qt-5/qcameraimagecapture.html#imageAvailable ?

[jenya7]

@jsulm said in A camera problem.:

@jenya7 So, what about trying https://doc.qt.io/qt-5/qcameraimagecapture.html#imageAvailable ?

I did in Camera::setCamera

connect(m_imageCapture.data(), &QCameraImageCapture::imageAvailable, this, &Camera::ImageAvailable);

and then

void Camera::ImageAvailable(int id, const QVideoFrame &frame)
{
     qDebug() <<  id;
     //qDebug() << frame->???;
}

I also added

void Camera::displayCameraError()
{
    //QMessageBox::warning(this, tr("Camera Error"), m_camera->errorString());
    qDebug() << "Camera Error: " + m_camera->errorString() + "\n";
}

void Camera::displayCaptureError(int id, const QCameraImageCapture::Error error, const QString &errorString)
{
    Q_UNUSED(id);
    Q_UNUSED(error);
    qDebug() << "Image Capture Error: " + errorString;
    m_isCapturingImage = false;
}

and when I do

g_camera.SetCaptureMode(QCamera::CaptureMode::CaptureStillImage);
g_camera.takeImage();

I get

"Image Capture Error: Camera not ready"

How can I know a reason why the camera isn't ready?

[jsulm]

@jenya7 Did you call

camera->setCaptureMode(QCamera::CaptureStillImage);
camera->start();
//on half pressed shutter button
camera->searchAndLock();

//on shutter button pressed
imageCapture->capture();

like shown in https://doc.qt.io/qt-5/qcameraimagecapture.html ?

[jenya7]

@jsulm said in A camera problem.:

@jenya7 Did you call

camera->setCaptureMode(QCamera::CaptureStillImage);
camera->start();
//on half pressed shutter button
camera->searchAndLock();

//on shutter button pressed
imageCapture->capture();

like shown in https://doc.qt.io/qt-5/qcameraimagecapture.html ?

I thought

void Camera::takeImage()
{
    m_isCapturingImage = true;
    m_imageCapture->capture();
}

handles all this, kinda higher layer that wraps all together.
and what is
//on half pressed shutter button
//on shutter button pressed
I don't have any buttons. my app is not widget controlled. all commands issued from a command line.
I took a widget camera example (from Examples) and removed all UI related staff.

[jsulm]

@jenya7 said in A camera problem.:

I don't have any buttons.

These comments simply tell you that these methods simulate these buttons.
So, yes you have to set the capture mode, start the camera, call searchAndLock and then capture.

[jenya7]

@jsulm said in A camera problem.:

@jenya7 said in A camera problem.:

I don't have any buttons.

These comments simply tell you that these methods simulate these buttons.
So, yes you have to set the capture mode, start the camera, call searchAndLock and then capture.

I changed to

void Camera::takeImage()
{
    m_camera->start();
    m_camera->searchAndLock();

    m_isCapturingImage = true;
    m_imageCapture->capture();
}

I still have
"Image Capture Error: Camera not ready"
Do I need to set a Viewfinder?
I commented out those lines

//QCameraViewfinder *v_finder = new QCameraViewfinder();
//v_finder->setFixedSize(240, 320);
//v_finder->show();
//v_finder->setAttribute(Qt::WA_NoSystemBackground);
//m_camera->setViewfinder(v_finder);

cause I get an exception on
QCameraViewfinder *v_finder = new QCameraViewfinder();

[jsulm]

@jenya7 For capturing images view finder should not be needed.
But you could try to enable it to see whether your camera works at all in Qt.
What exception do you get?

[jenya7]

@jsulm said in A camera problem.:

@jenya7 For capturing images view finder should not be needed.
But you could try to enable it to see whether your camera works at all in Qt.
What exception do you get?

I get
The inferior stopped because it received a signal from the operating system.
Signal name: SIGABRT
Signal meaning: Aborted

[jsulm]

@jenya7 Please run through debugger and post the stack trace.
Also, you should post your current code with enabled viewfinder.

[jenya7]

@jsulm said in A camera problem.:

@jenya7 Please run through debugger and post the stack trace.
Also, you should post your current code with enabled viewfinder.

void Camera::setCamera(const QCameraInfo &cameraInfo)
{
    m_camera.reset(new QCamera(cameraInfo));

    connect(m_camera.data(), &QCamera::stateChanged, this, &Camera::updateCameraState);
    connect(m_camera.data(), QOverload<QCamera::Error>::of(&QCamera::error), this, &Camera::displayCameraError);

    m_mediaRecorder.reset(new QMediaRecorder(m_camera.data()));
    connect(m_mediaRecorder.data(), &QMediaRecorder::stateChanged, this, &Camera::updateRecorderState);

    m_imageCapture.reset(new QCameraImageCapture(m_camera.data()));

    connect(m_mediaRecorder.data(), &QMediaRecorder::durationChanged, this, &Camera::updateRecordTime);
    connect(m_mediaRecorder.data(), QOverload<QMediaRecorder::Error>::of(&QMediaRecorder::error),
            this, &Camera::displayRecorderError);

    m_mediaRecorder->setMetaData(QMediaMetaData::Title, QVariant(QLatin1String("Test Title")));

    //connect(ui->exposureCompensation, &QAbstractSlider::valueChanged, this, &Camera::setExposureCompensation);

//here the exception occurs
   QCameraViewfinder *v_finder = new QCameraViewfinder();
    //v_finder->setFixedSize(240, 320);
    //v_finder->show();
    v_finder->setAttribute(Qt::WA_NoSystemBackground);
    m_camera->setViewfinder(v_finder);

    updateCameraState(m_camera->state());
    updateLockStatus(m_camera->lockStatus(), QCamera::UserRequest);
    updateRecorderState(m_mediaRecorder->state());

    connect(m_imageCapture.data(), &QCameraImageCapture::readyForCaptureChanged, this, &Camera::readyForCapture);
    connect(m_imageCapture.data(), &QCameraImageCapture::imageCaptured, this, &Camera::processCapturedImage);
    connect(m_imageCapture.data(), &QCameraImageCapture::imageSaved, this, &Camera::imageSaved);
    connect(m_imageCapture.data(), QOverload<int, QCameraImageCapture::Error, const QString &>::of(&QCameraImageCapture::error),
            this, &Camera::displayCaptureError);

    connect(m_imageCapture.data(), &QCameraImageCapture::imageAvailable, this, &Camera::ImageAvailable);

    connect(m_camera.data(), QOverload<QCamera::LockStatus, QCamera::LockChangeReason>::of(&QCamera::lockStatusChanged),
            this, &Camera::updateLockStatus);

    //ui->captureWidget->setTabEnabled(0, (m_camera->isCaptureModeSupported(QCamera::CaptureStillImage)));
    //ui->captureWidget->setTabEnabled(1, (m_camera->isCaptureModeSupported(QCamera::CaptureVideo)));

    updateCaptureMode(0);
    m_camera->start();
}

and a call stack

1  __GI_raise                                                  raise.c      50  0xb5830f14 
2  __GI_abort                                                  abort.c      79  0xb581c230 
3  QMessageLogger::fatal(const char *, ...) const                               0xb5c1c004 
4  QWidgetPrivate::QWidgetPrivate(int)                                          0xb698e204 
5  QWidget::QWidget(QWidget *, QFlags<Qt::WindowType>)                          0xb69ab42c 
6  QVideoWidget::QVideoWidget(QVideoWidgetPrivate&, QWidget *)                  0xb6f3ed70 
7  QCameraViewfinder::QCameraViewfinder(QWidget *)                              0xb6f388f4 
8  Camera::setCamera                                           camera.cpp   148 0x5a000        //this line is focused
9  Camera::Camera                                              camera.cpp   112 0x599ec    
10 __static_initialization_and_destruction_0                   camera.cpp   69  0x5bd58    
11 _GLOBAL__sub_I_camera.cpp(void)                             camera.cpp   544 0x5bdb4    
12 __libc_csu_init                                                              0xbed54    
13 __libc_start_main                                           libc-start.c 264 0xb581c6ac 
14 _start        

[jsulm]

@jenya7 I'm confused by the code you posted: sometimes you use m_camera. and sometimes m_camera->! How can this even compile?!

Try to set a parent on QCameraViewfinder to see whether it makes a difference.

[jenya7]

@jsulm said in A camera problem.:

@jenya7 I'm confused by the code you posted: sometimes you use m_camera. and sometimes m_camera->! How can this even compile?!

Try to set a parent on QCameraViewfinder to see whether it makes a difference.

Hmm..It's an example from the official Qt/Examples folder. I guess those with a dot - the intrinsic methods, not from a Camera class.

for example - m_camera.reset
from - C:\Qt\5.12.0\mingw73_64\include\QtCore\qscopedpointer.h

[jsulm]

@jenya7 No, this belongs to C++ basics: if m_camera is a pointer then you have to use -> if it is not a pointer then you have to use dot. So, what is m_camera in YOUR code?

[jenya7]

@jsulm said in A camera problem.:

@jenya7 No, this belongs to C++ basics: if m_camera is a pointer then you have to use -> if it is not a pointer then you have to use dot. So, what is m_camera in YOUR code?

in camera.h

class Camera : public QMainWindow
{
    Q_OBJECT

public:
    Camera(QObject *parent = nullptr);

     void takeImage();

private slots:
    void setCamera(const QCameraInfo &cameraInfo);

    void startCamera();
    void stopCamera();

    void record();
    void pause();
    void stop();
    void setMuted(bool);

    void toggleLock();
    void displayCaptureError(int, QCameraImageCapture::Error, const QString &errorString);

    void configureCaptureSettings();
    void configureVideoSettings();
    void configureImageSettings();
    void displayRecorderError();
    void displayCameraError();

    void updateCameraDevice(QAction *action);

    void updateCameraState(QCamera::State);
    void updateCaptureMode();
    void updateRecorderState(QMediaRecorder::State state);
    void setExposureCompensation(int index);

    void updateRecordTime();

    void processCapturedImage(int requestId, const QImage &img);
    void updateLockStatus(QCamera::LockStatus, QCamera::LockChangeReason);

    void displayViewfinder();
    void displayCapturedImage();

    void readyForCapture(bool ready);
    void imageSaved(int id, const QString &fileName);

protected:
    void keyPressEvent(QKeyEvent *event) override;
    void keyReleaseEvent(QKeyEvent *event) override;
    void closeEvent(QCloseEvent *event) override;

private:
    Ui::Camera *ui;

    QScopedPointer<QCamera> m_camera;

    QScopedPointer<QCameraImageCapture> m_imageCapture;
    QScopedPointer<QMediaRecorder> m_mediaRecorder;

    QImageEncoderSettings m_imageSettings;
    QAudioEncoderSettings m_audioSettings;
    QVideoEncoderSettings m_videoSettings;
    QString m_videoContainerFormat;
    bool m_isCapturingImage = false;
    bool m_applicationExiting = false;
};

It's a private member initialized after the camera found in a constructor.

Camera::Camera(QObject *parent) : QObject(parent) 
{
      //some code
      if (cameraInfo == QCameraInfo::defaultCamera())
              videoDeviceAction->setChecked(true);

       setCamera(QCameraInfo::defaultCamera());
}