install instruction:
https://www.ncnynl.com/archives/201703/1444.html
problem:
[ERROR] [1481169521.461465837]: Permission denied opening /dev/bus/usb/002/004
sudo chmod 777 /dev/bus/usb/002/004
[ INFO] [1520501259.328584270]: Opening camera with vendor=0x0, product=0x0, serial="", index=0
uvc_get_stream_ctrl_format_size: Invalid mode (-51)
Warning: USB events thread - failed to set priority. This might cause loss of data...