Black screen while run "declarative-camera" on Raspberry Pi 3
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Hi community,
I facing an issue when running examples from Qt Creator named "declarative-camera" on Raspberry Pi 3 leading to black screen instead of video.
The same project runs just fine on laptop (Ubuntu 16).
The point is that there are no debug logs nor any error / warning message.
Any ideas how to start to debug in order to find out "why" ?
Where is a start point to investigate? -
My first guess would be missing gstreamer-0.1 or gstreamer-1.0 libraries on your Pi.
Which Qt version are you using, by the way? Judging from name "declarative-camera" I fear you are still on Qt 4 instead of Qt 5.
Are you cross-compiling or have you built Qt natively on Pi?
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My first guess would be missing gstreamer-0.1 or gstreamer-1.0 libraries on your Pi.
Which Qt version are you using, by the way? Judging from name "declarative-camera" I fear you are still on Qt 4 instead of Qt 5.
Are you cross-compiling or have you built Qt natively on Pi?
@sierdzio Thanks for the replay and sorry for not provided full information initially.
I downloaded whichever is the latest Qt Creator available just a days ago:
Qt Creator 4.0.2
Based on Qt 5.7.0 (GCC 4.9.1 20140922 (Red Hat 4.9.1-10), 64 bit)
I installed gstreamer-0.9 and there is no other version installed, because I faced an issue with gstreamer-1.0 and Qt5.7 and found that it should be exactly version 0.9
I installed environment based on:
https://wiki.qt.io/RaspberryPi2EGLFS
However, I skipped section:
"if you are using a 64 bit Ubuntu you need to modify the above line to: "
But I do not think this could be an issue here.
So, I compiled it on my desktops Ubuntu and deploy into Raspberry Pi.
Application runs on Rasp Pi side, I am seeing GUI, but no video and there is no messages in the Application output at all.
I m wondering, is there a way to turn on debugging somehow? There must be something that prints debug messages. -
Hm, OK so your setup seems to be fine.
If you can't get the messages from the app, you can try installing a message handler: qInstallMessageHandler. This will allow you to - for example - save all the application output to some file on your rPi for later viewing.
I'm not sure if QML camera object handles EGLFS, never tried it myself.
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Hm, OK so your setup seems to be fine.
If you can't get the messages from the app, you can try installing a message handler: qInstallMessageHandler. This will allow you to - for example - save all the application output to some file on your rPi for later viewing.
I'm not sure if QML camera object handles EGLFS, never tried it myself.
@sierdzio
Basically I am trying to switch from Java / Python into C++ in order to get my projects work faster and efficiently by gaining C++ power, I am working on computer vision.
I found this example as more suitable for me to get Camera object on Rasp Pi.
Can you suggest any other / better way to get video stream with GUI?
Thanks in advance. -
Hey, I'm not saying your approach is wrong, only that I don't have enough experience in this area to help you further. Camera should work crossplatform, if it does not it is a bug in Qt, not yours.
Try with message handler - perhaps Qt is printing some crucial error info to the console and you miss it currently.
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Hey, I'm not saying your approach is wrong, only that I don't have enough experience in this area to help you further. Camera should work crossplatform, if it does not it is a bug in Qt, not yours.
Try with message handler - perhaps Qt is printing some crucial error info to the console and you miss it currently.
@sierdzio
Thanks anywhere!
Will try this evening to use it, let's see what I'll get. -
Ok,
I removed gstreamer 0.9 and 0.10 from RPi and installed 1.0.
Also, I included qInstallMessageHandler(myMessageOutput);
Now, I am facing the same issue as described here:
https://forum.qt.io/topic/52793/raspberry-pi-qt-5-3-2-qt-camera-not-working-no-service-found-for-org-qt-project-qt-cameraP.S.
At least I am seeing some useful message. However, as noticed in the provided post, I am not able to solve the new issue ... -
I found that "Unfortunately the GStreamer-based multimedia stuff is not quite usable at the time of writing - accelerated video works only sometimes (and with glitches), while the camera is just broken."
https://wiki.qt.io/RaspberryPi2EGLFS#Qt_MultimediaGoing to switch to:
https://github.com/raspberrypi/userland/tree/master/host_applications/linux/apps/raspicamThanks once again for the help :-)
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OK, that is what I suspected will be in the error messages.
Right then, happy coding with raspicam! :D
