[gst-devel] creating bins and ghostpads

[Aurelien Grimaud]

Add vidsource in pipeline ?

Rohan a écrit :
> Hi all,
>
> I am obviously doing something wrong here, but cannot figure out
> what.
>
> Essentially the pipeline is the same as the receiver but I have broken
> it into bins.  I seem to be having problems with the ghostpad, because
> I get this error:
>
> (stream_receiver.py:1914): GStreamer-WARNING **: Trying to connect elements that
> don't share a common ancestor: vidsource and vidbin
>
> Traceback (most recent call last):
>    File "stream_receiver.py", line 118, in <module>
>      server()
>    File "stream_receiver.py", line 27, in __init__
>      vidsource.link(vidbin)
> gst.LinkError: failed to link vidsource with vidbin
>
> Here is the code:
>
> ----------------------------------------------------------------------
> #!/bin/env python
>
> # The gst pipeline
> # pipe="udpsrc port=5000 ! smokedec ! autovideosink"
> # # audio
> # pipe="$pipe tcpclientsrc host=127.0.0.1 port=5001 ! "
> # pipe="$pipe speexdec ! queue ! alsasink sync=false "
>
> import sys,os
> import gobject
> import pygst
> pygst.require("0.10")
> import gst
>
> class server (object):
>      def __init__(self):
>          # start with video
>
>          self.pipe = gst.Pipeline("player")
>
>          # video source
>          vidsource = gst.element_factory_make("udpsrc", "vidsource")
>          vidsource.set_property("port", 5000)
>
>          vidbin = self.buildvid()
>          self.pipe.add(vidbin)
>          vidsource.link(vidbin)
>
>
>          self.pipe.set_state(gst.STATE_PLAYING)
>
>      def buildvid(self):
>          bin = gst.Bin("vidbin")
>          queue = gst.element_factory_make("queue")
>          smokedec = gst.element_factory_make("smokedec")
>          vidsink = gst.element_factory_make("autovideosink")
>          bin.add(queue, smokedec, vidsink)
>          gst.element_link_many(queue, smokedec, vidsink)
>
>          # ghostpad
>          binsink = gst.GhostPad("binsink", queue.get_pad("sink"))
>          bin.add_pad(binsink)
>          return bin
>
> if __name__ == "__main__":
>      server()
>      loop = gobject.MainLoop()
>      loop.run()
>
> ----------------------------------------------------------------------------
>
> What is driving me slightly nuts is that if I put all the buildvid code
> into init and have a long series of object instatiations with add to
> pipeline and link it works, but as soon as I started messing with
> ghostpads and bin (which makes the code much more manageable when
> adding functionality for windows and macs) this messed up.  Below is
> more code that works, and I cannot figure out why this and why not
> that.
>
> And the other thing is this does work in a commandline pipeline such
> as the one sitting at the top of the script in comments.
>
> I am using the same system for the sender, but I'll only include the
> local display.  This sends an image happily, using the build_localvid
> bin, and linking it to the camera.
>
> -----------------------------------------------------------------------------
> #!/bin/env python
>
> import sys, os
> import gobject
> import pygst
> pygst.require("0.10")
> import gst
>
> class client(object):
>
>      def __init__(self):
>          self.pipe = gst.Pipeline("sender")
>
>          # Initial video input
>          camera = gst.element_factory_make("v4l2src", "camera")
>          vidtee = gst.element_factory_make("tee", "vidtee")
>          self.pipe.add(camera, vidtee)
>          camera.link(vidtee)
>
>          # local video
>          localvidbin = self.build_localvid()
>          self.pipe.add(localvidbin)
>          vidtee.link(localvidbin)
>
>          self.pipe.set_state(gst.STATE_PLAYING)
>
>      def build_localvid(self):
>          """This bin takes a camera (video) stream and produces a live image
> locally."""
>          bin = gst.Bin("localvid")
>          queue = gst.element_factory_make("queue")
>          out = gst.element_factory_make("xvimagesink")
>          bin.add(out, queue)
>          queue.link_pads("src", out, "sink")
>          binsink = gst.GhostPad("binsink", queue.get_pad("sink"))
>          bin.add_pad(binsink)
>          return bin
>
> if __name__ == '__main__':
>      client()
>      loop = gobject.MainLoop()
>      loop.run()
>
> ---------------------------------------------------------------------------
>
> This does the correct thing, and I get a live image from the camera.
>
> I am completely stumped on this one, and have resorted to using
> gst.parse_bin_from_description() with the gst-launch pipeline, but
> this is far from ideal from a maintenance perspective. :)
>
> I am sure I am missing something pretty obvious, but so far flailing
> around in my ignorance has not let me stumble on a solution.
>
> Thanks for any help,
>
> Rohan
>
>
> ------------------------------------------------------------------------------
> Come build with us! The BlackBerry&reg; Developer Conference in SF, CA
> is the only developer event you need to attend this year. Jumpstart your
> developing skills, take BlackBerry mobile applications to market and stay 
> ahead of the curve. Join us from November 9&#45;12, 2009. Register now&#33;
> http://p.sf.net/sfu/devconf
> _______________________________________________
> gstreamer-devel mailing list
> gstreamer-devel at lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel
>
>
>