I am reporting an error while executing roslaunch. The open camera is black.

[TanJinXiao]

First of all, my configuration is ubuntu 18.04 ros melodic. When I want to use usb_cam, every time I execute roslaunch, I will report an error. The open screen is black and then stops automatically.

... logging to /home/tanjx/.ros/log/6bd3eacc-f6e1-11e8-8f94-d0577b77f434/roslaunch-tanjx-GL553VW-8345.log Checking log directory for disk usage. This may take awhile. Press Ctrl-C to interrupt Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://tanjx-GL553VW:33237/

SUMMARY

PARAMETERS

• /image_view/autosize: True
• /rosdistro: melodic
• /rosversion: 1.14.3
• /usb_cam/camera_frame_id: usb_cam
• /usb_cam/image_height: 480
• /usb_cam/image_width: 640
• /usb_cam/io_method: mmap
• /usb_cam/pixel_format: yuyv
• /usb_cam/video_device: /dev/video0

NODES / image_view (image_view/image_view) usb_cam (usb_cam/usb_cam_node)

auto-starting new master process[master]: started with pid [8355] ROS_MASTER_URI=http://localhost:11311

setting /run_id to 6bd3eacc-f6e1-11e8-8f94-d0577b77f434 process[rosout-1]: started with pid [8366] started core service [/rosout] process[usb_cam-2]: started with pid [8373] process[image_view-3]: started with pid [8374] [ INFO] [1543830868.026047240]: Using transport "raw" [ INFO] [1543830868.039452066]: using default calibration URL [ INFO] [1543830868.040194033]: camera calibration URL: file:///home/tanjx/.ros/camera_info/head_camera.yaml [ INFO] [1543830868.040256328]: Unable to open camera calibration file [/home/tanjx/.ros/camera_info/head_camera.yaml] [ WARN] [1543830868.040276160]: Camera calibration file /home/tanjx/.ros/camera_info/head_camera.yaml not found. [ INFO] [1543830868.040302240]: Starting 'head_camera' (/dev/video0) at 640x480 via mmap (yuyv) at 30 FPS

(image_raw:8374): GLib-GObject-CRITICAL **: 17:54:28.048: g_object_unref: assertion 'G_IS_OBJECT (object)' failed

(image_raw:8374): GLib-GObject-CRITICAL *: 17:54:28.102: g_object_unref: assertion 'G_IS_OBJECT (object)' failed [ERROR] [1543830873.224529361]: VIDIOC_S_FMT error 5, Input/output error [usb_cam-2] process has died [pid 8373, exit code 1, cmd /home/tanjx/catkin_ws/devel/lib/usb_cam/usb_cam_node __name:=usb_cam __log:=/home/tanjx/.ros/log/6bd3eacc-f6e1-11e8-8f94-d0577b77f434/usb_cam-2.log]. log file: /home/tanjx/.ros/log/6bd3eacc-f6e1-11e8-8f94-d0577b77f434/usb_cam-2.log

what should I do？！

[seekelvis]

I have the same problem. Did you solve it?

[magnuspyke]

This may be an issue that the default video_device is incorrect. Have you tried setting the video_device parameter to another /dev/videoX device? Also, try running

rosrun usb_cam usb_cam_node _video_device:=/dev/videoX (where X is your video device number)

and then viewing the image with rqt or rqt_image_view.

[SuperKuooo]

I am having the same problem. I tried both video0 and video1 inside the dev folder. Any update on this problem?

[dinara92]

v4l2-ctl --list-devices this command will show all videoX inside /dev, in my case there was up to video3, depending on num of connected cameras

[agrija9]

My ls /dev/video* outputs:

/dev/video0 /dev/video1 /dev/video2 /dev/video3

In my case, my usb camera corresponds to video2, so the following solves it:

rosrun usb_cam usb_cam_node _video_device:=/dev/video2

[Adharshmahesh]

Hi, I have the same problem. I listed the available devices using the command v4l2-ctl --list-devices. I tried to execute roslaunch usb_cam usb_cam-test.launch. I have tried changing all the device names. I only get a black screen. When I changed the pixel format to yuyv, I get a garbled green screen. Any ideas how to proceed?

[flynneva]

@Adharshmahesh you have to figure out what format your camera supports and change the settings of usb_cam to match. The ROS 2 version of this package will print out the version your HW supports if you want to try that out.

[Adharshmahesh]

@flynneva thank you for your response. I am using ROS1 noetic and not ROS2. I believe by format you mean pixel format. The pixel format of my camera is MJPEG (I can confirm this) and it matches with the pixel format in my launch file. I have posted a detailed version of my problem in ROS forum: https://answers.ros.org/question/405349/outbuf-size-mismatch-usb_cam/

[twdragon]

Closed listing here: http://wiki.ros.org/usb_cam/Troubleshooting