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Asked: 2024-09-24T22:24:59+05:30 In:

How can I configure my system to ensure that a particular webcam is assigned to a specific /dev/video device in Ubuntu?

So, I’ve been wrestling with this issue on my Ubuntu setup and I’m hoping someone here can help me out. I have this awesome webcam that I bought recently, and I really want to make sure it gets recognized as the same `/dev/video` device every time I plug it in. You know how it goes – sometimes it shows up as `/dev/video0`, other times it’s `/dev/video1`, and honestly, it’s driving me a bit crazy!

I’m setting up a video conferencing rig and need it to have a consistent device path because I’m using some scripts and software configurations that are picky about that sort of thing. I’ve read a bit about udev rules and how they can help with device management, but I’m not entirely sure about the steps or the right syntax to use.

I found my webcam with the command `lsusb`, and I’ve got all the details, including its vendor ID and product ID. Now, I’m trying to figure out how to write a proper udev rule that would take those IDs and ensure that my webcam consistently shows up as `/dev/video0`. I mean, I could just rename it in my scripts every time, but what a hassle that would be!

Has anyone done this before? I’m looking for a straightforward way to write the rule without getting too deep into the technical weeds. Maybe if you’ve run into something similar, you can share what worked for you. Also, if there are any potential pitfalls I should watch out for – like needing to restart services or issues with running it on different USB ports – that’d be super helpful to know.

Oh, and I’m not opposed to command line work, just want to make sure I don’t mess anything up in the process. Thanks in advance for your help! I really want to get this sorted out so I can focus on more important things, like making sure my cat doesn’t walk in front of the camera while I’m on a call!

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    2 Answers



    1. Webcam Udev Rule Guide

      Setting Up Udev Rules for Consistent Webcam Recognition

      It sounds like you’re having a frustrating time with your webcam being recognized by different device paths. Don’t worry; I can help you with that!

      What You Need to Do:

      1. First, you’ll want to gather the details of your webcam using lsusb. Look for the line that has your webcam and note down the Vendor ID and Product ID. It should look something like 1234:5678.
      2. Next, you’ll need to create a udev rule file. Open a terminal and run: 
        sudo nano /etc/udev/rules.d/99-webcam.rules
      3. Now, you need to write the rule. In the file, add the following line, replacing 1234 with your Vendor ID and 5678 with your Product ID: 
        KERNEL=="video*", SUBSYSTEM=="video4linux", ATTR{idVendor}=="1234", ATTR{idProduct}=="5678", SYMLINK+="video0"
      4. Save the file by pressing CTRL + X, then Y, and hit ENTER.
      5. Finally, reload the udev rules with: 
        sudo udevadm control --reload-rules

      What to Watch Out For:

      • You might need to unplug and plug in your webcam again for the changes to take effect.
      • If you change USB ports, the rule should still apply, but there’s a slight chance it might not. Keep that in mind!
      • Make sure you don’t have any other conflicting rules that might affect the webcam recognition.

      Testing It Out:

      After everything is set up, you can check if it worked by running ls -l /dev/video* and seeing if video0 points to your webcam. If it does, you’re all set!

      Now you can focus on video calls and not on constantly checking device paths. And good luck with your cat during the meetings!



    2. To ensure that your webcam consistently appears as `/dev/video0`, you can create a udev rule that binds the device to a specific path based on its vendor and product IDs. First, you need to gather the necessary information about your webcam. You already used `lsusb` to find the vendor ID (VID) and product ID (PID), which usually appear in a format like `1234:5678`. Once you have this information, you can create a udev rule. Open a terminal and navigate to the udev rules directory by running `sudo nano /etc/udev/rules.d/99-webcam.rules`. Add the following line to the new file: SUBSYSTEM=="video4linux", ATTR{idVendor}=="1234", ATTR{idProduct}=="5678", SYMLINK+="video0", replacing `1234` and `5678` with your webcam’s actual VID and PID. This rule specifies that when the device is connected, it should create a symbolic link named `video0` to your webcam device.

      After adding the rule, save the file and exit. To apply the changes immediately, run `sudo udevadm control –reload-rules` followed by `sudo udevadm trigger`. It’s also a good idea to unplug and then re-plug your webcam to see if it’s assigned to `/dev/video0`. Be cautious with USB ports, as connecting your device to a different port may impact how Linux recognizes the device. If the webcam still does not appear as expected, consider adding more attributes to the udev rule or inspecting the output of `dmesg` after plugging in your webcam for more diagnostics. Always ensure that your changes are correctly formatted to avoid issues, and remember to keep backups of your rule changes in case you need to revert.


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