Re: Python script + v4lctl

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  • Gabriel Genellina

    Re: Python script + v4lctl

    En Mon, 20 Oct 2008 06:15:34 -0200, Gatis <gatisl@inbox.l vescribió:
    I wrote script that in case of some event takes picture using usb
    webcam [Creative Live! Cam Vista IM (VF0420)] and command line utility
    v4lctl (from package xawtv).
    Problem1:
    To catch error and info messages from script I used:
    sys.stdout = open('/tmp/log','a')
    sys.stderr=sys. stdout
    All writes to log file well, except v4lctl error messages. If script
    is run from commandline, than v4lctl error messages are shown there.
    How to catch these messages?
    Use the subprocess module to invoke the external program; see
    http://docs.python.org/library/subprocess.html specially the examples at
    the end.
    Problem2:
    When script is run from /etc/init.d (in runlevel 2) during boot, no
    pictures are taken. I can't tell error message, because of Problem1.
    If I execute now v4lctl from commandline (while my script is running
    in background), picture is taken.
    Once you start using subprocess, you could write to some file what you get
    from the communicate() method - the error messages, if any, should be
    there.

    --
    Gabriel Genellina

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