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QML Camera doesn't work properly



  • Hello
    I run declarative-camera which is one of Qt examples on imx6q also set QT_GSTREAMER_CAMERABIN_VIDEOSRC value properly but the video freezed and below messages appear on screen whenever I try to unplug and plug the video connector again :

    ** CRITICAL **: gst_audio_format_from_string: assertion 'format != NULL' failed
    ERROR: v4l2 capture: slave not found!
    Unable to query the parameter info: QCameraImageProcessingControl::WhiteBalancePreset : "Invalid argument"
    Unable to query the parameter info: QCameraImageProcessingControl::ColorTemperature : "Invalid argument"
    Unable to query the parameter info: QCameraImageProcessingControl::ContrastAdjustment : "Invalid argument"
    Unable to query the parameter info: QCameraImageProcessingControl::SaturationAdjustment : "Invalid argument"
    Unable to query the parameter info: QCameraImageProcessingControl::BrightnessAdjustment : "Invalid argument"
    Unable to query the parameter info: QCameraImageProcessingControl::SharpeningAdjustment : "Invalid argument"
    ERROR: v4l2 capture: unsupported ioctrl!
    
    (Chopper:173): GStreamer-CRITICAL **: Registering meta implementation 'GstImxV4l2Meta' without init function
    ERROR: v4l2 capture: mxc_streamon buffer need ping pong at least two buffers
    ERROR: v4l2 capture: mxc_v4l_dqueue timeout enc_counter 0
    CameraBin error: "Internal data stream error."
    ERROR: v4l2 capture: unsupported ioctrl!
    
    

    The main problem is "mxc_streamon buffer need ping pong at least two buffers"
    When i run below command everything is right by gstreamer even I unplug and plug the video connector no matter how many time I do that :
    gst-launch-1.0 imxv4l2videosrc ! imxipuvideosink

    I appreciate any help

    Yours,


  • Lifetime Qt Champion

    Hi,

    What version of Qt are you using ?



  • Dear @SGaist ,
    I checked on two versions of QT :
    5.9.2 and 5.11.1
    they had same error.

    Is there any way to not to use qml Camera type and VideoOutput to use gstreamer pipeline directly and putting its sink on qml gui?



  • @SGaist
    hi i faced same error
    is there any solution

    Qt 5.15 EGLFS Raspberry Pi
    (all gstreamer plugins installed ... )



  • I have the same problem with ELP HD Usb camera. Probably the problem with the camera hardware, I think there is no WhiteBalance for example.
    You should get camera stream from Usb till qt library has fixed.


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