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When I plug in the camera to Linux then I get 2 devices /dev/video0 and /dev/video1 Why is that happens and is that normal? Odd numbered devices do not work. /dev/v4l/by-path looks like that:

lrwxrwxrwx 1 root root 12 dets  15 01:29 pci-0000:00:14.0-usb-0:14:1.0-video-index0 -> ../../video0
lrwxrwxrwx 1 root root 12 dets  15 01:29 pci-0000:00:14.0-usb-0:14:1.0-video-index1 -> ../../video1

/dev/v4l/by-id looks like that:

lrwxrwxrwx 1 root root 12 dets  15 01:29 usb-_Webcam_C170-video-index0 -> ../../video0
lrwxrwxrwx 1 root root 12 dets  15 01:29 usb-_Webcam_C170-video-index1 -> ../../video1

I tested it with 2 computers(Kubuntu 18.10) and with 4 different cameras. it makes always 2 devices.

Edit added dmesg output:

[118541.028706] usb 1-14: new high-speed USB device number 12 using xhci_hcd
[118541.254215] usb 1-14: New USB device found, idVendor=046d, idProduct=082b, bcdDevice=28.25
[118541.254221] usb 1-14: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[118541.254225] usb 1-14: Product: Webcam C170
[118541.254229] usb 1-14: Manufacturer:  
[118541.310835] media: Linux media interface: v0.10
[118541.323429] videodev: Linux video capture interface: v2.00
[118541.332766] usbcore: registered new interface driver snd-usb-audio
[118541.334867] uvcvideo: Found UVC 1.00 device Webcam C170 (046d:082b)
[118541.354970] uvcvideo 1-14:1.0: Entity type for entity Processing 2 was not initialized!
[118541.354971] uvcvideo 1-14:1.0: Entity type for entity Extension 6 was not initialized!
[118541.354972] uvcvideo 1-14:1.0: Entity type for entity Camera 1 was not initialized!
[118541.355016] input: Webcam C170: Webcam C170 as /devices/pci0000:00/0000:00:14.0/usb1/1-14/1-14:1.0/input/input51
[118541.355077] usbcore: registered new interface driver uvcvideo
[118541.355078] USB Video Class driver (1.1.1)
  • 1
    It depends on the camera model. What does ls -l /dev/v4l/by-id look like? If a camera has an error in its USB device/endpoint descriptors (= within the camera firmware), it might well produce strange results like this. – telcoM Dec 14 '18 at 11:29
  • I added details – Paxmees Dec 14 '18 at 23:37
  • What does dmesg say (relevant lines at the time shortly after plugging the camera)? – Hermann Dec 15 '18 at 0:02
  • What about lsusb? And lspci if it has any pertinent information. – kjensenxz Dec 27 '18 at 9:54

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