roboflex.webcam_uvc

Support for web cameras on linux - actually just a thin wrapper around libuvc, so if your camera supports libuvc, you should be good to go.

System dependencies

apt-get install libusb-1.0-0-dev
apt-get install libjpeg-dev

# ...or, on mac:

brew install libusb

pip install

pip install roboflex.webcam_uvc

Import

import roboflex.webcam_uvc as rcw

Nodes

There is only one: WebcamSensor

# all parameters optional: below are the defaults
webcam_sensor = rcw.WebcamSensor(
    width,
    height,
    fps,
    device_index = -1,
    format = UVC_FRAME_FORMAT_ANY,
    name = "WebcamSensor",
)

# must be started!
webcam_sensor.start()

# you can do this:
webcam_sensor.print_device_info()

Messages

from roboflex.webcam_uvc import WebcamDataRGB

API:

# the timestamp just before reading from device
message.t0 -> Float

# the timestamp just after reading from device
message.t1 -> Float

# the capture time from the device
message.capture_time -> Float

# the sequence number from the device
message.sequence -> Int

# numpy array of shape=(width, height, channels), dtype=short
message.rgb -> np.ndarray

DYNOFLEX:

# the timestamp just before reading from device
message["t0"] -> Double

# the timestamp just after reading from device
message["t1"] -> Double

# the capture time from the device
message["t"] -> Double

# the sequence number from the device
message["s"] -> Double

# numpy array of shape=(width, height, channels), dtype=short
message["rgb"] -> np.ndarray

Other

Description of a device:

from roboflex.webcam_uvc import DeviceDescriptor

dd.idVendor -> int
dd.idProduct -> int
dd.bcdUVC -> int
dd.serialNumber -> str
dd.manufacturer -> str
dd.product -> str

# you probably just want to print it:
str(dd)

Free function: get list of connected devices (webcams) - list of DeviceDescriptor, above.

get_device_list() -> [DeviceDescriptor]

Available frame formats: pass to constructor of WebcamSensor for the format parameter.

from roboflex.webcam_uvc import uvc_frame_format

uvc_frame_format.UVC_FRAME_FORMAT_ANY
uvc_frame_format.UVC_FRAME_FORMAT_UNCOMPRESSED
uvc_frame_format.UVC_FRAME_FORMAT_COMPRESSED

# YUYV/YUV2/YUV422: YUV encoding with one luminance value per pixel and
# one UV (chrominance) pair for every two pixels.
uvc_frame_format.UVC_FRAME_FORMAT_YUYV
uvc_frame_format.UVC_FRAME_FORMAT_UYVY

# 24-bit RGB
uvc_frame_format.UVC_FRAME_FORMAT_RGB
uvc_frame_format.UVC_FRAME_FORMAT_BGR

# Motion-JPEG (or JPEG) encoded images
uvc_frame_format.UVC_FRAME_FORMAT_MJPEG
uvc_frame_format.UVC_FRAME_FORMAT_H264

# Greyscale images
uvc_frame_format.UVC_FRAME_FORMAT_GRAY16
uvc_frame_format.UVC_FRAME_FORMAT_GRAY8

# Raw colour mosaic images
uvc_frame_format.UVC_FRAME_FORMAT_BY8
uvc_frame_format.UVC_FRAME_FORMAT_BA81
uvc_frame_format.UVC_FRAME_FORMAT_SGRBG8
uvc_frame_format.UVC_FRAME_FORMAT_SGBRG8
uvc_frame_format.UVC_FRAME_FORMAT_SRGGB8
uvc_frame_format.UVC_FRAME_FORMAT_SBGGR8

# YUV420: NV12
uvc_frame_format.UVC_FRAME_FORMAT_NV12

# Number of formats understood
uvc_frame_format.UVC_FRAME_FORMAT_COUNT

Linux webcam help

Access denied to your webcam?

First, list your usb devices and find your webcam:

lsusb

For me, I see:

Bus 002 Device 025: ID 32e4:9230 HD USB Camera HD USB Camera

create a file called '50-usb-webcam.rules' in /etc/udev/rules.d with a single line:

SUBSYSTEM=="usb", ATTR{idVendor}="HD USB Camera", ATTR{idProduct}="HD USB Camera", MODE="0666"

then

udevadm control --reload-rules && udevadm trigger