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Thread: Webcam shows just black screen in Lucid

  1. #11
    Join Date
    May 2005
    Location
    Boston, MA, United States
    Beans
    112
    Distro
    Ubuntu 11.04 Natty Narwhal

    Question Re: Webcam shows just black screen in Lucid

    Webcam didn't open when I ran mplayer tv:// in terminal, but that's probably good because it gave me a bunch of output:

    Code:
    MPlayer SVN-r1.0~rc3+svn20090426-4.4.3 (C) 2000-2009 MPlayer Team
    mplayer: could not connect to socket
    mplayer: No such file or directory
    Failed to open LIRC support. You will not be able to use your remote control.
    
    Playing tv://.
    TV file format detected.
    Selected driver: v4l2
     name: Video 4 Linux 2 input
     author: Martin Olschewski <olschewski@zpr.uni-koeln.de>
     comment: first try, more to come ;-)
    v4l2: your device driver does not support VIDIOC_G_STD ioctl, VIDIOC_G_PARM was used instead.
    Selected device: Camera
     Capabilites:  video capture  read/write  streaming
     supported norms:
     inputs: 0 = spca561;
     Current input: 0
     Current format: unknown (0x31363553)
    tv.c: norm_from_string(pal): Bogus norm parameter, setting default.
    v4l2: ioctl enum norm failed: Invalid argument
    Error: Cannot set norm!
    Selected input hasn't got a tuner!
    v4l2: Cannot get fps
    v4l2: ioctl set mute failed: Invalid argument
    v4l2: ioctl query control failed: Invalid argument
    v4l2: ioctl query control failed: Invalid argument
    v4l2: ioctl query control failed: Invalid argument
    open: No such file or directory
    [MGA] Couldn't open: /dev/mga_vid
    open: No such file or directory
    [MGA] Couldn't open: /dev/mga_vid
    [VO_TDFXFB] Can't open /dev/fb0: Permission denied.
    [VO_3DFX] Unable to open /dev/3dfx.
    ==========================================================================
    Cannot find codec matching selected -vo and video format 0x31363553.
    Read DOCS/HTML/en/codecs.html!
    ==========================================================================
    
    v4l2: ioctl set mute failed: Invalid argument
    v4l2: 0 frames successfully processed, 0 frames dropped.
    
    Exiting... (End of file)
    'To be nobody but yourself in a world which is doing its best, night and day, to make you like everybody else means to fight the hardest battle which any human being can fight; and never stop fighting.'
    --e.e. cummings

  2. #12
    Join Date
    Sep 2009
    Beans
    2,330

    Re: Webcam shows just black screen in Lucid

    we had to try it
    i got the same as you on 2 computers 1 804 1 910
    and booth my cams work


    have i had you get this program yet wxcam

    i find this 1 to work if cheese does not

    read and install all the page tells you to

    http://wxcam.sourceforge.net/


    or try xawtv

  3. #13
    Join Date
    May 2005
    Location
    Boston, MA, United States
    Beans
    112
    Distro
    Ubuntu 11.04 Natty Narwhal

    Question Re: Webcam shows just black screen in Lucid

    I tried xawtv and it didn't work. I just installed wxcam and opened it, and got this error:

    Code:
    An error has occurred during frame capture.
    Please check the "frame format" options in the preferences menu.
    I had a look, but I'm not sure what I should reset it to. Its default setting is 'Auto' which you'd think would work! I tried all of them; some gave me the same error, while others tried to show me a picture but just gave me lots of green noise. I downsized the image from 352x288 to 176x144 and now I see myself (only with some 'frame format' settings, most notably YUV420P - other 'frame format' settings still give me that error), but with weird colours - the top half of the image is yellow and the bottom half is pink, but about once a second it flashes so that the top half is blue and the bottom half is green - and there's a bunch of noise all over it as well. Sizing it down more, to 88x72, just turns it into pink static with no flashing or anything, just what seems to be a still image of pink static.

    When I start wxcam in terminal with YUV420P as the frame format, I get this output:

    Code:
    Determining video4linux API version...
    Using video4linux 2 API
    VIDIOC_ENUM_FRAMESIZES: Invalid argument
    V4L2_CID_BRIGHTNESS is not supported
    V4L2_CID_CONTRAST is not supported
    V4L2_CID_GAMMA is not supported
    V4L2_CID_SATURATION is not supported
    Using V4L2_PIX_FMT_YUV420 pixel format
    What's the 'VIDIOC_ENUM_FRAMESIZES: Invalid argument' about? And why are those other settings not supported? Is any of that part of my problem with Cheese and Skype?
    Last edited by ftmichael; June 14th, 2010 at 07:43 PM.
    'To be nobody but yourself in a world which is doing its best, night and day, to make you like everybody else means to fight the hardest battle which any human being can fight; and never stop fighting.'
    --e.e. cummings

  4. #14
    Join Date
    May 2005
    Location
    Boston, MA, United States
    Beans
    112
    Distro
    Ubuntu 11.04 Natty Narwhal

    Question Re: Webcam shows just black screen in Lucid

    Okay, I just opened Cheese again, and I have picture now. I have no clue what changed. I uninstalled wxcam to see if Cheese would still work, and it did.

    Skype was fixed by changing the menu command from skype to bash -c 'export LD_PRELOAD=/usr/lib/libv4l/v4l2convert.so; skype' as recommended elsewhere. That didn't help anything before, but now that Cheese seems happy with the webcam, Skype's willing to work as well.

    I'd still like to know what the problem was so I can fix it if it happens again, or if anyone else has the same problem. Therefore I'm hesitant to mark this thread [SOLVED].
    Last edited by ftmichael; June 14th, 2010 at 09:14 PM.
    'To be nobody but yourself in a world which is doing its best, night and day, to make you like everybody else means to fight the hardest battle which any human being can fight; and never stop fighting.'
    --e.e. cummings

  5. #15
    Join Date
    Oct 2005
    Beans
    520

    Re: Webcam shows just black screen in Lucid

    You could try using the following , except replacing camstream with your app.

    LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so camstream

    I use a creative instant web cam that only uses the v4l-1 not -2

    Hope that helps

  6. #16
    Join Date
    Sep 2009
    Beans
    2,330

    Re: Webcam shows just black screen in Lucid

    cheese has a good help file look in its faq's


    its a shame wxcam does not work for you
    i can click it open and record in 5 sec

    you should get it back and play with it a lot

    have only seen 1 say they got the mic to work with cheese


    but all in all glad you got it working

    edit your first post to read solved
    Last edited by no2498; June 15th, 2010 at 08:00 PM. Reason: edit your first post to read solved

  7. #17
    Join Date
    Jun 2010
    Beans
    4

    Re: Webcam shows just black screen in Lucid

    EDIT: when I mention Movie Player below I mean Totem (did not realise it was Totem until I looked in help)

    I have a similar problem with Cheese and Skype.

    The webcam is working (can take photos & record video in Cheese).
    And soon as I play back the recorded Video (with Movie Player) Cheese will display a picture!

    Have not tested Skype with anyone yet. Just the blank screen in Options>Video>Test.

    BUT this all resolves itself as soon as I run Movie Player.

    Had the same problem with VLC (sound but no picture).
    Changing the output options fixed this for VLC tho.
    In Vlc Preferences> video> output > "x11 video output"

    any thoughts ?
    could always just set Movie Player to run on startup I guess...
    Last edited by anto27373; June 29th, 2010 at 05:24 AM. Reason: as stated above

  8. #18
    Join Date
    Feb 2009
    Location
    Slovenia
    Beans
    34
    Distro
    Ubuntu 10.04 Lucid Lynx

    Re: Webcam shows just black screen in Lucid

    Skype was fixed by changing the menu command from skype to bash -c 'export LD_PRELOAD=/usr/lib/libv4l/v4l2convert.so; skype' as recommended elsewhere. That didn't help anything before, but now that Cheese seems happy with the webcam, Skype's willing to work as well.
    This solved it for me as well. Thanks.

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