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Thread: More VLC woes

  1. #1
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    Default More VLC woes

    Since I have two installs (one desktop and one laptop) that are essentially identical, it is confounding to me that I can open a webcam on one computer and not the other. Trying to look at file differences between the two, I got a more confusing situation. The working version (laptop) opens a stream from the webcam and briefly the screen shows "v4l2://" On the desktop, trying the same webcam gives me the error that I cannot open "MRL v4l2://" BTW, I have one usb webcam that I move back and forth between these computers.

    Looking for the files or location in question, I see the desktop has many, many more files in the v4l2 directory, including a half dozen rpm files. I cannot delete these. Yast says it has deleted them but they remain. Dolphin will not give me the option to delete when I right-click on them. I copy the file names (copy, not type) to try zypper rm. Zypper says no such file, even though I'm looking at it. All the files/folders related to v4l2 on both machines are owned by root. I was thinking I could delete the v4l2 folder and it would recreate itself properly somehow, even if I had to download some rpm's again. Still that scares me as a sledgehammer approach that might not even work.

    So, even if I can't get the webcam working, I'd like to know why these rpm files are permanent.
    Any sufficiently advanced technology is indistinguishable from magic. - Arthur C. Clarke

  2. #2
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    Default Re: More VLC woes

    Quote Originally Posted by Prexy View Post
    Since I have two installs (one desktop and one laptop) that are essentially identical, it is confounding to me that I can open a webcam on one computer and not the other. Trying to look at file differences between the two, I got a more confusing situation. The working version (laptop) opens a stream from the webcam and briefly the screen shows "v4l2://" On the desktop, trying the same webcam gives me the error that I cannot open "MRL v4l2://" BTW, I have one usb webcam that I move back and forth between these computers.
    I can only offer general advice here, but it seems to me that you were having these issues weeks ago...
    https://forums.opensuse.org/showthre...4-webcam/page5

    With respect to the VLC error, I expect it reported something like "VLC is unable to open the MRL 'file:///dev/video0'. Check the log for details". Did you then check the log?

    As per the advice in this thread start vlc in verbose mode (for debugging)
    Code:
    vlc --verbose 2
    VLC log...
    Code:
    cat ~/vlclog.txt
    That might help yield further useful information, otherwise we can only speculate.

    More info:
    https://forum.videolan.org/viewtopic.php?t=3092
    openSUSE Leap 15.2; KDE Plasma 5

  3. #3
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    Default Re: More VLC woes

    Thank you deano_ferrari for trying to help.

    You're right. I gave up for awhile after the previous posts for help. That's why I tried a new thread.
    Code:
    The vlc --verbose 2 command
    gives me a great deal of output. I can post it but it is dozens and dozens of lines. I have to confess my ignorance. I didn't know where to look for the log referred to in the error message. With your advice, I ran
    Code:
    cat ~/vlclog.txt
    but the result was
    Code:
    /vlclog.txt: No such file or directory
    I did this, obviously, on the problem computer. I'm going to go boot up the laptop and run these again for comparison purposes.
    Any sufficiently advanced technology is indistinguishable from magic. - Arthur C. Clarke

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    Default Re: More VLC woes

    Booted up the laptop and opened the webcam. It worked as expected. I ran the two commands and looked for differences from the desktop. There still was no vlclog.txt but scrolling back through the verbose output I found errors in the webcam output.
    Code:
    [00007f9ec8001120] v4l2 demux error: not a video capture device
    [00007f9ec8001120] v4l2 demux debug: opening device '/dev/radio0'
    [00007f9ec8001120] v4l2 demux error: cannot open device '/dev/radio0': No su
    ch file or directory
    
    This error is repeated but refers to "no streaming device." These errors do not appear on the laptop where the webcam is working properly. At first, I thought a solution would be to buy a new webcam. But, why would the results be different? Also, the webcam has a built-in mic which works on the laptop. I presume that mic is the source of the error message about radio.
    Any sufficiently advanced technology is indistinguishable from magic. - Arthur C. Clarke

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    Default Re: More VLC woes

    What does the following report?
    Code:
    v4l2-ctl --list-devices
    openSUSE Leap 15.2; KDE Plasma 5

  6. #6
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    Default Re: More VLC woes

    Quote Originally Posted by deano_ferrari View Post
    What does the following report?
    Code:
    v4l2-ctl --list-devices
    I get this:
    Code:
    v4l2-ctl --list-devices
    MyPhone Camera (platform:v4l2loopback-000):
            /dev/video0
    
    Webcam (platform:v4l2loopback-001):
            /dev/video1
    
    USB2.0 PC CAMERA (usb-0000:00:1d.0-1.8):
            /dev/video2
            /dev/video3
            /dev/media0
    
    
    That is the desktop where it fails. On the laptop, where it works, I get only the part starting with USB2.0. Before I found this webcam in the garage, I tried using an old cellphone as a cam with a couple of different apps and files from the repo. I wonder if there is a conflict from this lingering software. I also tried selecting video0 through video3 specifically instead of letting vlc select what it saw as default. There was no option to select media0. The result was always the same: failure.
    Any sufficiently advanced technology is indistinguishable from magic. - Arthur C. Clarke

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    Default Re: More VLC woes

    What is reported by the following?
    Code:
    ls -l /dev/video*
    openSUSE Leap 15.2; KDE Plasma 5

  8. #8
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    Default Re: More VLC woes

    Quote Originally Posted by deano_ferrari View Post
    What is reported by the following?
    Code:
    ls -l /dev/video*
    Code:
    crw-rw----+ 1 root video 81, 0 Jan 27 15:57 /dev/video0
    crw-rw----+ 1 root video 81, 1 Jan 27 15:57 /dev/video1
    
    
    Any sufficiently advanced technology is indistinguishable from magic. - Arthur C. Clarke

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