问ARToolKit无法识别U盘摄像头

EN

No video config string supplied, using defaults.
ioctl failed

r@r-K55VD:~/Downloads/Artoolkit-on-Ubuntu-12.04-master/bin$ ./simpleTest
Using supplied video config string [v4l2src device=/dev/video0 use-fixed-fps=false ! ffmpegcolorspace ! capsfilter caps=video/x-raw-rgb,width=640,height=480 ! identity name=artoolkit ! fakesink].
ARVideo may be configured using one or more of the following options,
separated by a space:

DEVICE CONTROLS:
 -dev=filepath
    specifies device file.
 -channel=N
    specifies source channel.
 -noadjust
    prevent adjusting the width/height/channel if not suitable.
 -width=N
    specifies expected width of image.
 -height=N
    specifies expected height of image.
 -palette=[RGB|YUV420P]
    specifies the camera palette (WARNING:all are not supported on each camera !!).
IMAGE CONTROLS (WARNING: every options are not supported by all camera !!):
 -brightness=N
    specifies brightness. (0.0 <-> 1.0)
 -contrast=N
    specifies contrast. (0.0 <-> 1.0)
 -saturation=N
    specifies saturation (color). (0.0 <-> 1.0) (for color camera only)
 -hue=N
    specifies hue. (0.0 <-> 1.0) (for color camera only)
 -whiteness=N
    specifies whiteness. (0.0 <-> 1.0) (REMARK: gamma for some drivers, otherwise for greyscale camera only)
 -color=N
    specifies saturation (color). (0.0 <-> 1.0) (REMARK: obsolete !! use saturation control)

OPTION CONTROLS:
 -mode=[PAL|NTSC|SECAM]
    specifies TV signal mode (for tv/capture card).