Integrating Raspberry Pi Camera with Qt application

harshshah5789

I am making a hobby project of digital still camera based on Raspberry Pi using Qt.

I have cross compiled Qt on Pi and able to successfully run a normal test Qt application on Pi.
Also the raspistill and raspivid utilities are running successfully.

The issue is with integrating the Rasp Pi camera. Before buying it I din't knew that it does not support v4l2.

I want to show a live view of camera in the Qt application and capture the image when a Button is clicked.

What are the options except v4l2, for getting the live feed from camera in Qt.

blueshift

"OpenCV":http://opencv.org/about.html is popular for accessing webcam/camera with Qt.

m_rx

there is a driver in uv4l http://www.linux-projects.org/modules/sections/index.php?op=viewarticle&artid=14 which i get half-working.
but, when starting an application employing a qml-camera "hangs" the ui - meaning that the ui is never visible.
if i leave preview enabled in uv4l, the camera preview is visible and running.
no matter if preview is visible or not, the ui never shows up.

i also get the following output @0:00:08.941350183 3460 0xe03a00 INFO 0:00:08.944484126 3460 0xe03a00 INFO 0:00:08.951060008 3460 0xe03a00 INFO 0:00:08.953317968 3460 0xe03a00 INFO 0:00:08.955501928 3460 0xe03a00 INFO 0:00:08.958525875 3460 0xe03a00 INFO 0:00:08.961976813 3460 0xe03a00 INFO 0:00:08.965648747 3460 0xe03a00 INFO 0:00:08.968530695 3460 0xe03a00 INFO 0:00:08.973310609 3460 0xe03a00 INFO 0:00:08.976061559 3460 0xe03a00 INFO 0:00:08.979186503 3460 0xe03a00 INFO 0:00:08.982253448 3460 0xe03a00 INFO 0:00:08.984377409 3460 0xe03a00 INFO 0:00:08.986682369 3460 0xe03a00 INFO 0:00:08.988741331 3460 0xe03a00 INFO 0:00:08.990976291 3460 0xe03a00 INFO @
after that the program stops, looks as if driver and qt can't when running via "GST_DEBUG="*:3" ./<app>":
GST_STATES gstelement.c:2460:gst_element_continue_state:<camera_source> completed state change to READY
GST_STATES gstelement.c:2365:_priv_gst_element_state_changed:<camera_source> notifying about state-changed NULL to READY (VOID_PENDING pending)
default camerabingeneral.c:136:gst_camerabin_try_add_element:<camera_source> no unlinked source pad in bin
GST_ELEMENT_PADS gstelement.c:975:gst_element_get_static_pad: found pad camera_source:src
GST_ELEMENT_FACTORY gstelementfactory.c:374:gst_element_factory_create: creating element "ffmpegcolorspace" named "src-colorspace"
GST_ELEMENT_PADS gstelement.c:728:gst_element_add_pad:GstBaseTransform@0x11a6f38 adding pad 'sink'
GST_ELEMENT_PADS gstelement.c:728:gst_element_add_pad:GstBaseTransform@0x11a6f38 adding pad 'src'
GST_ELEMENT_PADS gstutils.c:1698:gst_element_link_pads_full: trying to link element camera_source:(any) to element src-colorspace:(any)
GST_PADS gstutils.c:1032:gst_pad_check_link: trying to link camera_source:src and src-colorspace:sink
v4l2 gstv4l2object.c:1105:gst_v4l2_object_fill_format_list:<camera_source> got 7 format(s):
v4l2 gstv4l2object.c:1111:gst_v4l2_object_fill_format_list:<camera_source> YU12
v4l2 gstv4l2object.c:1111:gst_v4l2_object_fill_format_list:<camera_source> JPEG
v4l2 gstv4l2object.c:1111:gst_v4l2_object_fill_format_list:<camera_source> MJPG
v4l2 gstv4l2object.c:1111:gst_v4l2_object_fill_format_list:<camera_source> YV12 (emulated)
v4l2 gstv4l2object.c:1111:gst_v4l2_object_fill_format_list:<camera_source> BGR3 (emulated)
v4l2 gstv4l2object.c:1111:gst_v4l2_object_fill_format_list:<camera_source> RGB3 (emulated)
v4l2 gstv4l2object.c:1111:gst_v4l2_object_fill_format_list:<camera_source> H264
no ui shown, camera light is on.
find a common format ...

any ideas?

xvause

Hello,

Have you found a solution ?
I'm trying the same, but I can't integrate my Pi Camera in a simple Qt Project...

mrdebug

You can use raspican, a library written in C to manage raspberry pi webcam. In the past I tryed it but I had a problem with the red light. Now I use the executable directly.

Soppe

This is old, but in case someone else encounters this error, the fix should be the following:

sudo rpi-update (once)
modprobe bcm2835-v4l2 gst_v4l2src_is_broken=1 (every reboot).

First part of modprobe is to enable the /dev/video0 stream and v4l2, the latter is to prevent camera from hanging application.

Solution taken from here

Sandip

Try using https://github.com/cedricve/raspicam raspicam to capture camera image. Not sure how to display image on QOpenGLWidget. it works good to capture image from camera but OpenGL scene render not works. Anyone able to render scene using QOpenGLWidget

Sandip

@mrdebug How did you mange to render the camera frame to QT widget? Would you please help me to render scene and display frame on QOpenGLWidget?

mrdebug

Hi. Now I'm using the raspicam library to get images and if you want you can use QLabel to display it on a raspberry pi display. OpenGL in not mandatory.