Capturing multiple webcams (uvcvideo) with OpenCV on Linux

Question

I am trying to simultaneously stream the images from 3 Logitech Webcam Pro 900 devices using OpenCV 2.1 on Ubuntu 11.10. The uvcvideo driver gets loaded for these.

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Answer 1

With kernel 4.15.0-34-generic on Ubuntu 18.04 and OpenCV 3.4 compiled with gstreamer/v4l support I am able to stream 3x720p on a single USB port using a powered hub using MJPG compression with gstreamer in python (using 2xC922 and 1xC920 cameras - the 10fps framerate isn't necessary for this to work):

def open_cam_usb(dev, width, height):
    gst_str = (
        "v4l2src device=/dev/video{} ! "
        "image/jpeg,widh=(int){},height=(int){},framerate=10/1,"
        "format=(string)RGB ! "
        "jpegdec ! videoconvert ! appsink"
    ).format(dev, width, height)
    return cv2.VideoCapture(gst_str, cv2.CAP_GSTREAMER)