[bug PyQt 5.15.2] segmentation fault using QVideoFilterRunnable

[Phil Thompson]

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