[bug PyQt 5.15.2] segmentation fault using QVideoFilterRunnable

[Adrian Fiergolski]

On 11.02.2021 11:36, Phil Thompson wrote:
> On 11/02/2021 09:55, Adrian Fiergolski wrote:
>> On 11.02.2021 at 10:48, Phil Thompson wrote:
>>> On 11/02/2021 09:19, Adrian Fiergolski wrote:
>>>> On 10.02.2021 at 23:09, Phil Thompson wrote:
>>>>> On 10/02/2021 17:53, Adrian Fiergolski wrote:
>>>>>> On 10.02.2021 18:35, Phil Thompson wrote:
>>>>>>> On 10/02/2021 16:30, Adrian Fiergolski wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> I am getting segmentation fault using QVideoFilterRunnable. I
>>>>>>>> try to
>>>>>>>> follow the example from the documentation.
>>>>>>>>
>>>>>>>> I am enclosing the testcase and the log from the debugger (gdb).
>>>>>>>>
>>>>>>>> My setup: yocto (with meta-qt5 gatesgarth, PyQt 5.15.2) running on
>>>>>>>> Cortex A-53, kernel 5.4).
>>>>>>>>
>>>>>>>> I got the same issue with PyQt 5.13.2 on my embedded platform. The
>>>>>>>> problem is reproducible on a PC (running Ubuntu 20.04 with
>>>>>>>> installed
>>>>>>>> qt5-default and pyqt5-dev).
>>>>>>>>
>>>>>>>> Once the filter is commented out (case.qml:17), everything runs
>>>>>>>> smoothly.
>>>>>>>>
>>>>>>>> Do you know any workaround for that? I need to process data from a
>>>>>>>> camera in OpenCV (I wanted to do it the QVideoFilterRunnable:run)
>>>>>>>> and
>>>>>>>> paint the resulting processed frame.
>>>>>>>
>>>>>>> I suspect that this needs hard-coded support for
>>>>>>> QVideoFilterRunnable
>>>>>>> in the same way that PyQt supports QValidator in QML.
>>>>>>>
>>>>>>> There is no workaround that I'm aware of.
>>>>>>
>>>>>> Hi Phil,
>>>>>>
>>>>>> Thank you for your reply. I am new to Qt. Could you elaborate on
>>>>>> your
>>>>>> answer?
>>>>>
>>>>> I'm not sure what you mean - PyQt would need to be enhanced to
>>>>> support
>>>>> this particular use case.
>>>>>
>>>>> Phil
>>>>
>>>> So which use case of QVideoFilterRunnable and QAbstractVideoFilter is
>>>> currently supported in PyQt?
>>>
>>> Using them from QML.
>>>
>>> Phil
>>
>> Could you point please to some example? Would it be still possible to
>> execute python from this QML object which would do manipulations with
>> the frame (OpenCV) and return a new frame to QML QVideoFilterRunnable?
>
> Sorry, I've never used OpenCV or video filters in Qt.
>
> Phil

Was anybody able to reproduce the bug? Has any bug ticket been created?

In the documentation [1] I find information that:

"QAbstractVideoFilter is meant to be subclassed. The subclasses are then
registered to the QML engine, so they can be used as a QML type."

Thus, how could I use QAbstractVideoFilter in QML as Phill suggested?

Adrian

[1]https://doc.qt.io/qt-5/qabstractvideofilter.html