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  1. Qt
  2. QTBUG-97464

[Boot2Qt] Multimedia CaptureSession initialization outputs gstreamer errors, inconsistent startup



    • Bug
    • Resolution: Done
    • P1: Critical
    • 6.2.1
    • 6.2.0
    • Multimedia
    • None
    • Raspberry pi 4 4GB model, 32GB storage, same webcam. OS built off of the v6.2.0 file in the boot2qt-manifests repo with no changes at all.
    • Linux/Yocto


      When launching an application in b2qt there are errors that pop up every single time that a CaptureSession object exists regardless of what's inside. Even a file with just Window { CaptureSession {}} will cause this, but in the example attached there is more that doesn't have any effect on these error messages but shows other b2qt multimedia issues.
      qt.core.qobject.connect: QObject::connect: signal not found in QProcess
      "QT_IM_MODULE" "qtvirtualkeyboard"
      "QT_QPA_EGLFS_FORCE888" "1"
      "QT_QPA_PLATFORM" "eglfs"
      "WAYLAND_DISPLAY" "/run/wayland-0"
      "XDG_RUNTIME_DIR" "/run/user/0"
      "/opt/basic_camera_test/bin/basic_camera_test" QList()
      QML debugging is enabled. Only use this in a safe environment.

      (basic_camera_test:883): GLib-GObject-WARNING **: 12:21:02.917: g_object_set_is_valid_property: object class 'GstQueue' has no property named 'D\x97\xab\xb0'

      The "g_object_set_is_valid_property: object class 'GstQueue' has no property named" bit is always there regardless of if it functions or not, but it is around a 50/50 shot of if a camera shows up on the screen at all. The actual property name seems almost random, as doing multiple runs in a row gets me the following properties in order:"'D\x97\x9b\xb0\xf8<\xe2', 'D7Z\xb1', 'D\x97\xab\xb0\xb8%\x9d\u0001`\x90\xa0\u0001\x98\xed\x9c\u0001', 'D?', 'D\x97\xab\xb0xA\xee\u0001`\xc0\xf1\u0001\x98\xef\xf0\u0001', 'D\x97\xab\xb0', and 'D\x97\xab\xb0\xf0&\xc0'" with the actual video feed popping up twice in that time.

      For B2qt there is also an issue where half of the time the VideoOutput doesn't load at all. This doesn't happen at all on desktop Linux, and does seem to be coorelated with invalid hex characters in those error messages where ones with characters like '`' or '<' or '&' don't start the video output, but ones that have no invalid characters do display video, albeit at a horrible framerate.

      These issues also persist when using the Widgets Camera example, so it's not just QML related.


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            laknoll Lars Knoll
            patrickgroh Patrick Groh
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