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Thread: webcam quality poor - libv4l2: error allocating conversion buffer

  1. #1

    Default webcam quality poor - libv4l2: error allocating conversion buffer

    Hi all,

    OS: Opensuse 11.4
    Webcam: Bus 002 Device 002: ID 046d:08ac Logitech, Inc. QuickCam Cool
    Error Message: libv4l2: error allocating conversion buffer

    The quality of my webcam output is very poor.
    I am uncertain as to what I can do to resolve this.

    Any help would be greatly appreciated.

    Thank you

  2. #2
    Join Date
    Mar 2008
    Phuket, Thailand
    Blog Entries

    Default Re: webcam quality poor - libv4l2: error allocating conversion buffer

    I note from the logitech site that this 046d:08ac is a webcam tat uses the spca driver : Non-UVC webcams — QuickCam Team (with a note beside the entry "This camera is untested. Please let us know if you have tested this camera (successfully or not)" )

    This is confirmed by the 046d:08ac not being on the UVC list: Linux UVC driver & tools and being located on the spca5 list:

    I confess I was never happy with the performance under GNU/Linux of spca/gspca compatible webcams, and instead I much prefer (and now will only purchase) webcams that are UVC compatible.

    I gave away all the gspca/spca webcams that we had in our family to MS-Windows users, and instead I have a policy now of purchasing webcams that are UVC compatible.

    The openSUSE wiki has this on webcams: HCL:Web cameras - openSUSE

    and it notes that for some gspca compatible webcams, some applications still don't work very well together with the new drivers, a workaround is to preload a libv4l-compat library:
    LD_PRELOAD=/usr/lib/libv4l/ <application>
    before starting the respective application, i.e. for kopete you would type:
    LD_PRELOAD=/usr/lib/libv4l/ kopete
    This compat-library can be found in the package "libv4l", which is available from OSS-Repo or (recommended) from Packman. (see - Additional YaST Package Repositories)
    If you have a 64 bit system, you preload the library with:
    LD_PRELOAD=/usr/lib64/libv4l/ <application>
    If you want to run a 32 bit application (i.e. skype) on a 64 bit system, you first need to install "libv4l-32bit" (only available in the Packman repository) and run the preload-command used for 32 bit.
    If this works for you, you can add the LD_PRELOAD-command to the startup command of your menu entry/desktop shortcut via menu editor or with right-clicking the desktop icon => properties => application => command respectively.

    = = = =

    Having typed the above, if were me I would give that webcam away to an MS-Windows user, and purchase a webcam that has superior GNU/Linux compatibility, such as a webcam that is UVC compatible.

  3. #3

    Default Re: webcam quality poor - libv4l2: error allocating conversion buffer


    Thank you for the in depth reply. I really appreciate it.

    I am already loading skype by using the command
    LD_PRELOAD=/usr/lib/libv4l/ skype
    I am running a 32 bit version of skype within a 64 bit machine.
    Skype does not detect the webcam without preloading the library.

    when I type in the command v4l-conf it displays the following output

    v4l-conf: using X11 display :0
    dga: version 2.0
    WARNING: No DGA direct video mode for this display.
    mode: 1280x960, depth=24, bpp=32, bpl=5120, base=unknown
    /dev/video0 [v4l2]: no overlay support
    I think I may be out of luck on this occasion.

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