Timothy Litvin
Building a custom mobile robotics platform, I’ve been monkeying with Linux, BeagleBone Blue and ArduPlane and Mission Planner for a few months. Communicating via wifi. It’s been a rutted road, but I’ve gotten that portion to work. I was greatly relieved to find a well-written beginner’s book dedicated to the BBBlue is now available, the 2nd edition of BeagleBone Robotics Projects.
Nevertheless, I’m stuck on what seems like should be a dirt-simple thing: viewing a webcam (Chapter 5). I’m using a Logitech C920 webcam, powered thru a USB hub (I’ve tried powering it direct-to-BB too). I can SSH in on wifi and I see /dev/video1 ...(not video0):
kimo@beaglebone:~$ cd /dev
kimo@beaglebone:/dev$ ls
apm_bios media1 spidev1.1 tty29 tty53 ttyS5
autofs mem stderr tty3 tty54 ubi_ctrl
block memory_bandwidth stdin tty30 tty55 uhid
btrfs-control mmcblk0 stdout tty31 tty56 uinput
bus mmcblk0p1 tty tty32 tty57 urandom
char mmcblk1 tty0 tty33 tty58 v4l
console mmcblk1boot0 tty1 tty34 tty59 vcs
cpu_dma_latency mmcblk1boot1 tty10 tty35 tty6 vcs1
cuse mmcblk1p1 tty11 tty36 tty60 vcs2
disk mqueue tty12 tty37 tty61 vcs3
dri net tty13 tty38 tty62 vcs4
fd network_latency tty14 tty39 tty63 vcs5
full network_throughput tty15 tty4 tty7 vcs6
fuse null tty16 tty40 tty8 vcsa
hwrng port tty17 tty41 tty9 vcsa1
i2c-0 ppp tty18 tty42 ttyGS0 vcsa2
i2c-1 psaux tty19 tty43 ttyO0 vcsa3
i2c-2 ptmx tty2 tty44 ttyO1 vcsa4
initctl pts tty20 tty45 ttyO2 vcsa5
input random tty21 tty46 ttyO3 vcsa6
kmem rfkill tty22 tty47 ttyO4 vga_arbiter
kmsg rtc tty23 tty48 ttyO5 video1
lightnvm rtc0 tty24 tty49 ttyS0 watchdog
log shm tty25 tty5 ttyS1 watchdog0
loop-control snapshot tty26 tty50 ttyS2 xconsole
mapper snd tty27 tty51 ttyS3 zero
media0 spidev1.0 tty28 tty52 ttyS4
and lsusb reports it:
kimo@beaglebone:~$ lsusb
Bus 001 Device 010: ID 046d:082d Logitech, Inc. HD Pro Webcam C920
Bus 001 Device 005: ID 05e3:0610 Genesys Logic, Inc. 4-port hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
I’ve installed and started vncserver. I’ve installed guvcview, but it won’t start as it seems to be looking for a wrong configuration file in a non-existent directory:
kimo@beaglebone:/dev$ guvcview
GUVCVIEW: couldn't open /home/kimo/.config/guvcview2/video0 for read: No such file or directory
V4L2_CORE: ERROR opening V4L interface: No such file or directory
Unable to init server: Could not connect: Connection refused
GUVCVIEW: (GUI) Gtk3 can't open display
Guvcview error: no video device found
Of course, confirming on my Windows 10 machine, using TightVNC Viewer, ->Applications menu->Multimedia->guvcview, it’s not finding my Logitech C920: “no device found”.
Pretty sure I followed the recipe by the book, and have checked it repeatedly. I need to borrow better eyes or a bigger brain.
What did I miss? How do I tweak this? Ultimately I want to run two or more USB cameras through OpenCV.
Btw, proofreading, there’s a typo and font disparity on pp105 of the BBRP2E book, an executable command instructing us noobs to “make sure you start the server… by typing VNC server via SSH”, i.e., “vncserver”.)
Dennis Lee Bieber
<capnt...@gmail.com> declaimed the
following:
>
>I’ve installed and started vncserver. I’ve installed guvcview, but it won’t
>start as it seems to be looking for a wrong configuration file in a
>non-existent directory:
>
>
>kimo@beaglebone:/dev$ guvcview
>
>GUVCVIEW: couldn't open /home/kimo/.config/guvcview2/video0 for read: No
>such file or directory
>
>V4L2_CORE: ERROR opening V4L interface: No such file or directory
>
>Unable to init server: Could not connect: Connection refused
>
>GUVCVIEW: (GUI) Gtk3 can't open display
>
>Guvcview error: no video device found
>
>
http://guvcview.sourceforge.net/Doc.html
"""
Configuration
Guvcview stores all options into a configuration file stored in the user
home directory under .config/guvcview2/video0. The file is opened at start
and it is rewritten at exit. By removing the file the default values will
be loaded, and a new file will be written at exit.
For other devices than the default video0, the configuration file name will
have a device sufix, videoN, where N is the device number, this allows
different configurations for different devices.
Just remember that device numbering depends on the usb port the device is
connected, so if you plug your cameras to different ports each time, you
will end up with the wrong configuration.
"""
Is there any command line option to specify different video devices?
(the web site only says to use "man gucview")
{Okay -- installed in my Debian 9.1 virtual machine...
GUVCVIEW(1) General Commands Manual GUVCVIEW(1)
NAME
guvcview - GTK+ base UVC Viewer
SYNOPSIS
guvcview
DESCRIPTION
Guvcview is a simple GTK+ interface for capturing and viewing
video
from devices supported by the Linux UVC driver. It fully
supports
video4linux2 so it should work with any driver that supports this
API,
including the gspca driver.
USAGE
guvcview [options...]
OPTION
-h, --help Print help
-v, --version Print version
-w, --verbosity=LEVEL Set Verbosity level
(def:
0)
-d, --device=DEVICE Set device name
(def:
/dev/video0)
and many more...
--
Wulfraed Dennis Lee Bieber AF6VN
wlf...@ix.netcom.com HTTP://wlfraed.home.netcom.com/