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Problem on QCamera auto exposure



  • Hi!
    I use qt for starting camera and recording on Windows. And I met some questions.
    I need to set my camera auto exposure (if it's support) so I write code like this.

    //Before these codes I new a object of QCamera(m_camera) and set what I need
            QCameraExposure *exposure = m_camera->exposure();
    	auto curExposureMode = exposure->exposureMode();
    	auto isSupportExposureAuto = exposure->isExposureModeSupported(QCameraExposure::ExposureAuto);
    	exposure->setExposureMode(QCameraExposure::ExposureAuto);
            m_camera->start();
    

    And the result is: curExposureMode is "QCameraExposure::ExposureAuto" and isSupportExposureAuto is false. But I see with AMCap, my camera is support auto exposure and I have set the exposure to manual mode before. And after I set the exposure auto, there is nothing changed on my camera(it is still manual exposure mode).

    So is there anyone can tell me what's wrong with my code?
    Thanks!


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    What version of Qt are you using ?
    What is AMCap ?
    What does it use to communicate with that camera ?

    You don't have anything wrong in your code. The backend used to communicate with the camera however might not be able to set the exposure.



  • Thanks for your help.
    The version of QT is 5.7.0.
    "AMCap" is a software that can tell me whether the camera is support auto exposure and other settings. You can download here(https://amcap.en.softonic.com/).
    I use AMCap and set my camera auto exposure, it runs good.So I think my camera is support auto exposure.But with the follow code I get the different answer.

    auto isSupportExposureAuto = exposure->isExposureModeSupported(QCameraExposure::ExposureAuto);
    //the result is false
    

  • Lifetime Qt Champion

    You should use a more recent version of Qt.
    The current release is 5.11, LTS is 5.9 and 5.12 is around the corner.



  • OK, I will try again with Qt5.11.0. Thank you very much!


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