qt 5.12.2 "camera example" crash at startup

Lim SAS

Hello eveyone,
I've been using "camera example" of QT 5.12.2 in ubuntu 18_04 and everyting was fine.

Then, when I moved to Ubuntu 22_04, this exemple crash at startup.
Debugger show that it is always in the same thread, called "viewfinderbin-q"

I've tried online installer, that provides QT 5.15.3, I have the same issue with the same consequence

Please notice that the QML camera example work fine, I can see my face on webcam !.

Any idea how to make camera example work ?

many thanks

SamiV123

@Lim-SAS

build from source with debug info, run in the debugger and have a look at the stack trace.

JoeCFD

@Lim-SAS I just tested this example with 5.15.3 on LUbuntu 22.04 and did not have problem to launch it.

Lim SAS

@SamiV123 I will try it next week.

Lim SAS

@JoeCFD Thanks for the try.

Q1) You were able to see the camera display in real time ?

Q2) how did you install qt-creator and the multimedia library (offline installer ? sources compilation? online installer ? ubuntu packages ?)

JoeCFD

@Lim-SAS Sorry I did not see camera display in real time because I do not have camera in my computer. qtcreator is installed by
sudo apt-get install qtcreator.

Lim SAS

@JoeCFD
ah, ok ... My app crashes only when a camera is there. If not, there is no crash.

Lim SAS

@SamiV123 said in qt 5.12.2 "camera example" crash at startup:

source with debug info, run in the debug

I have been fallowing the https://wiki.qt.io/Building_Qt_5_from_Git tutorial but the compilation fails at early stage. it's annoying.

jsulm

@Lim-SAS said in qt 5.12.2 "camera example" crash at startup:

compilation fails at early stage

If you provide more details maybe somebody will help

Lim SAS

@jsulm
Sure, but I think it will take too much time for uncertain result. I will persevere in this way when I will be really desperate ;)

As written here : https://doc.qt.io/qt-5/supported-platforms.html
there is no support of QT5 for ubuntu 22_04. Maybe my issue has no solution.

jsulm

@Lim-SAS said in qt 5.12.2 "camera example" crash at startup:

there is no support of QT5 for ubuntu 22_04

This is wrong. Qt5 works just fine with Ubuntu 22.04. There is no mention of Ubuntu 22.04 simply because it did not exist when that page was created.
Ubuntu 22.04 even provides Qt5 packages...

Lim SAS

@jsulm
good news !
I wish someone could reproduce my issue. I will reinstall ubuntu from scratch on another computer to double check i'm not crazy

JoeCFD

@Lim-SAS Try the following to see if you can find something if gstreamer is applied in this example.
export GST_DEBUG=5
or run
strace app
to see if something is obvious.

Lim SAS

@JoeCFD
after reinstalling ubuntu 22.04 from scratch, I now have an error that is displayed at the very beginning of runtime:
cameraBin error : "Internal error: could not render surface"
cameraBin error : "Internal data stream error"

after 4 hours of search of a similar problem on the internet, I could not find any solution. Does it ring a bell to you ?

Lim SAS

fyi : with a ubuntu 20.04 installation from scratch, camera display works fine...

Ketan__Patel__0011

@Lim-SAS
You can see this video about Qt Camera Functionlity Or Qt Multimedia Moudle Functionlity.

Qt Camera (Connect Camera With Application) : https://youtu.be/hcf9V5R0G6s?si=qLzR2nOpuFnN-4i_

Qt Camera And QCameraImageCapture (Camera ImageCapture) :
https://youtu.be/CUBoN1Hk168?si=YhjeMQbBGIGvCk3n

Lim SAS

just found how to fix it !
execute the magic : sudo apt purge gstreamer1.0-vaapi
then it's ok.

I hope it helps