QtQr crashes when clicking "decode from webcam" button

[john doe]

Just fresh installed Debian 10 on laptop that has a working webcam. Then installed QtQr version 1.4~bzr32-1 via apt-get. QtQr works fine except when I click on the "decode from webcam" button. Here's what I see in the terminal:

$ qtqr
Traceback (most recent call last):
  File "/usr/bin/qtqr", line 833, in decodeWebcam
    qr.decode_webcam(device=device)
  File "/usr/lib/python2.7/dist-packages/qrtools.py", line 239, in decode_webcam
    proc.init(device)
zbar.UnsupportedError: WARNING: zbar processor in _zbar_v4l2_probe():
    unsupported request: v4l2 device does not support usable CAPTURE
Aborted

[Ramiro Algozino (algozino)]

Hello,

I can't replicate the error on Ubuntu. Any way, is not a QtQR bug/problem,
there's something that zbar (the library we use to decode using the webcam)
that doesn't like about your webcam or the driver you are using. Please try
using zbar directly and let me know if you have the same error, if you do
please report the bug to them. If you don't, we can see if there's
something we can do from the QtQR side.

Thanks.

Regards,

Il Gio 1 Ago 2019, 04:15 john doe <email address hidden> ha scritto:

> Public bug reported:
>
> Just fresh installed Debian 10 on laptop that has a working webcam. Then
> installed QtQr version 1.4~bzr32-1 via apt-get. QtQr works fine except
> when I click on the "decode from webcam" button. Here's what I see in
> the terminal:
>
> $ qtqr
> Traceback (most recent call last):
> File "/usr/bin/qtqr", line 833, in decodeWebcam
> qr.decode_webcam(device=device)
> File "/usr/lib/python2.7/dist-packages/qrtools.py", line 239, in
> decode_webcam
> proc.init(device)
> zbar.UnsupportedError: WARNING: zbar processor in _zbar_v4l2_probe():
> unsupported request: v4l2 device does not support usable CAPTURE
> Aborted
>
> ** Affects: qr-tools
> Importance: Undecided
> Status: New
>
> --
> You received this bug notification because you are a member of QR Tools
> Team, which is subscribed to QR Tools.
> https://bugs.launchpad.net/bugs/1838593
>
> Title:
> QtQr crashes when clicking "decode from webcam" button
>
> Status in QR Tools:
> New
>
> Bug description:
> Just fresh installed Debian 10 on laptop that has a working webcam.
> Then installed QtQr version 1.4~bzr32-1 via apt-get. QtQr works fine
> except when I click on the "decode from webcam" button. Here's what I
> see in the terminal:
>
> $ qtqr
> Traceback (most recent call last):
> File "/usr/bin/qtqr", line 833, in decodeWebcam
> qr.decode_webcam(device=device)
> File "/usr/lib/python2.7/dist-packages/qrtools.py", line 239, in
> decode_webcam
> proc.init(device)
> zbar.UnsupportedError: WARNING: zbar processor in _zbar_v4l2_probe():
> unsupported request: v4l2 device does not support usable CAPTURE
> Aborted
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qr-tools/+bug/1838593/+subscriptions
>

[Launchpad Janitor (janitor)]

[Expired for QR Tools because there has been no activity for 60 days.]

[Xanatos (xanatos00)]

Hello,

Same issue, with laptop with built-in camera on Debian Buster unknown version, my package version is: qtqr 2.0~bzr33-2
This camera is disabled by default.
I toggle on before using it with hotkey, then launch qtqr, when I use "decode from webcam", qtqr crash:

Traceback (most recent call last):
  File "/usr/bin/qtqr", line 834, in decodeWebcam
    qr.decode_webcam(device=device)
  File "/usr/lib/python3/dist-packages/qrtools.py", line 240, in decode_webcam
    proc.init(device)
zbar.UnsupportedError: <zbar.Processor object at 0x7f90a802ae40>
Abandon

If I retry, it will works the second or third time.
I patched with a try except this line to prevent crash, I have now the following message, but application continues:

qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 552, resource id: 16379793, major code: 40 (TranslateCoords), minor code: 0

Regards

[Ramiro Algozino (algozino)]

Hello!

Thanks for reaching out, I don't think your problem is related with the original poster. The OP was using a virtual webcam that is currently unsupported.

For your issue on the other hand, I think it might be that your webcam needs some time to be fully available, have you tried waiting some minutes before trying to decide? Have you checked dmesg to see if the webcam is available?

Thanks

Ramiro Algozino
https://algozino.com.ar/
On Jan 12, 2021, 00:35 +0100, Xanatos <email address hidden>, wrote:
> Hello,
>
> Same issue, with laptop with built-in camera on Debian Buster unknown version, my package version is: qtqr 2.0~bzr33-2
> This camera is disabled by default.
> I toggle on before using it with hotkey, then launch qtqr, when I use "decode from webcam", qtqr crash:
>
> Traceback (most recent call last):
> File "/usr/bin/qtqr", line 834, in decodeWebcam
> qr.decode_webcam(device=device)
> File "/usr/lib/python3/dist-packages/qrtools.py", line 240, in decode_webcam
> proc.init(device)
> zbar.UnsupportedError: <zbar.Processor object at 0x7f90a802ae40>
> Abandon
>
> If I retry, it will works the second or third time.
> I patched with a try except this line to prevent crash, I have now the following message, but application continues:
>
> qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 552,
> resource id: 16379793, major code: 40 (TranslateCoords), minor code: 0
>
>
> Regards
>
> --
> You received this bug notification because you are a member of QR Tools
> Team, which is subscribed to QR Tools.
> https://bugs.launchpad.net/bugs/1838593
>
> Title:
> QtQr crashes when clicking "decode from webcam" button
>
> Status in QR Tools:
> Expired
>
> Bug description:
> Just fresh installed Debian 10 on laptop that has a working webcam.
> Then installed QtQr version 1.4~bzr32-1 via apt-get. QtQr works fine
> except when I click on the "decode from webcam" button. Here's what I
> see in the terminal:
>
> $ qtqr
> Traceback (most recent call last):
> File "/usr/bin/qtqr", line 833, in decodeWebcam
> qr.decode_webcam(device=device)
> File "/usr/lib/python2.7/dist-packages/qrtools.py", line 239, in decode_webcam
> proc.init(device)
> zbar.UnsupportedError: WARNING: zbar processor in _zbar_v4l2_probe():
> unsupported request: v4l2 device does not support usable CAPTURE
> Aborted
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qr-tools/+bug/1838593/+subscriptions

[cdannebe (christiandanneberg)]

Hi,
thanks for your work. I am using qtqr version 2.0~bzr33-2 under Debian 11. I assume this is the bug as reported here for Ubuntu. Maybe it is a matter of access rights?

Regards, Christian.

PS: Maybe the output of my bash helps.

Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway.
QPixmap::scaled: Pixmap is a null pixmap
Traceback (most recent call last):
  File "/usr/bin/qtqr", line 834, in decodeWebcam
    qr.decode_webcam(device=device)
  File "/usr/lib/python3/dist-packages/qrtools.py", line 240, in decode_webcam
    proc.init(device)
zbar.UnsupportedError: <zbar.Processor object at 0x7fadaf7a4c40>

[Ramiro Algozino (algozino)]

Hi cdannebe,

You are using a quite old version, could you please try with the latest one? You can download the deb packages from the daily PPA[0] if you don't want to add it to your system.

[0] https://code.launchpad.net/~qr-tools-developers/+archive/ubuntu/daily/+packages

Let me know if you still have the issue using "qtqr - 2.1-0~45~ubuntu21.04.1"

Thanks!