stream recorder

[umlaeute]

implement a video recorder and make it controllable from the gui

[umlaeute]

we probably need a separate bin for this.
according to the gst-launch-1.0 manpage this can be done with:

    Bins

    [BINTYPE.] ( [PROPERTY1 ...] PIPELINE-DESCRIPTION )

    Specifies  that  a bin of type BINTYPE is created and the given proper‐
    ties are set. Every element between the braces is  put  into  the  bin.
    Please  note  the  dot  that has to be used after the BINTYPE. You will
    almost never need this functionality, it  is  only  really  useful  for
    applications  using  the  gst_launch_parse() API with ’bin’ as bintype.
    That way it is possible to build partial pipelines instead of  a  full-
    fledged top-level pipeline.

e.g. gst-launch-1.0 videotestsrc ! "bin.(xvimagesink)" (uses double-quotes to prevent bash from handling () specially)