uvc_camera initialization problem

Question

camera_node fails to launch with the following errors at terminal :

core service [/rosout] found Exception AttributeError: AttributeError("'_DummyThread' object has no attribute '_Thread__block'",) in <module 'threading' from '/usr/lib/python2.7/threading.pyc'> ignored process[uvc_camera-1]: started with pid [2733] [ INFO] [1342037003.291072134]: camera calibration URL: file:///opt/ros/fuerte/stacks/camera_umd/uvc_camera/example.yaml [ERROR] [1342037003.292045722]: Unable to open camera calibration file [/opt/ros/fuerte/stacks/camera_umd/uvc_camera/example.yaml] [ WARN] [1342037003.292174788]: Camera calibration file /opt/ros/fuerte/stacks/camera_umd/uvc_camera/example.yaml not found. opening /dev/video0 terminate called after throwing an instance of 'std::runtime_error' what(): couldn't open /dev/video0 [uvc_camera-1] process has died [pid 2733, exit code -6, cmd /opt/ros/fuerte/stacks/camera_umd/uvc_camera/bin/camera_node __name:=uvc_camera __log:=/home/sudhanshu/.ros/log/7fb92ae8-cb7d-11e1-8f5e-080027007ada/uvc_camera-1.log]. log file: /home/sudhanshu/.ros/log/7fb92ae8-cb7d-11e1-8f5e-080027007ada/uvc_camera-1*.log all processes on machine have died, roslaunch will exit shutting down processing monitor... ... shutting down processing monitor complete done

tired to run it from root, but it didn't help out. I am trying to stream images from one PC to another PC..over my LAN. It works sometimes without flaw .. other times it doesn't initialize. Would appreciate some guidance on this. Thanks !

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Originally posted by nanite on ROS Answers with karma: 11 on 2012-07-11

Post score: 1

Answer 1

try running ls -l /dev/video0 which should produce this:

crw-rw---- 1 root video 81, 0 Jul 20 19:26 /dev/video0 

if the first part of the message looks this:

crw-rw----

like the above then you don't have the correct permissions so type this:

sudo chmod a+rw /dev/video0

the final message should look like this:

crw-rw-rw- 1 root video 81, 0 Jul 20 19:26 /dev/video0

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Originally posted by ggamble22 with karma: 61 on 2012-07-20

This answer was ACCEPTED on the original site

Post score: 2

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Original comments

Comment by Kevin_chow on 2018-03-22:
hi, I encountered the same problem, i followed your instruction, it worked, but the camera driver died soon, and i looked up the permissions, it turned out likes this "crw-rw----" again, It bothers me for a long time, do you know why?