Embedding scripting language in a filter element

[Michael Grüner]

The core won't handle python elements by itself. The trick is that there is a python plugin that works as a python element loader that will do the job.

It didn't work out of the box for me, here's what I did:

1)  Check if it isn't working already

~# gst-inspect python
No such element or plugin 'python'

2) Inspect the library explicitely to see what the problem may be. I bet you already have this lib installed,  if not,  I'm pretty sure it comes in python-gst

~# gst-inspect /usr/lib/gstreamer-0.10/libgstpython.so 
ImportError: No module named pygtk

3) Extend python path with the missing pygtk module location.  This may vary in your system.

~# export PYTHONPATH=/usr/lib/python2.7/dist-packages/
~# gst-inspect /usr/lib/gstreamer-0.10/libgstpython.so 
Plugin Details:
  Name:            python
  Description:        loader for plugins written in python
  Filename:        /usr/lib/gstreamer-0.10/libgstpython.so
  Version:        0.10.22
  License:        LGPL
  Source module:    gst-python
  Source release date:    2011-10-29
  Binary package:    GStreamer Python Bindings
  Origin URL:        http://gstreamer.freedesktop.org


  0 features:

4) The plugin will likely continue to appear as unexistent because it has been blacklisted on the registry. Force registry regeneration.

~# gst-inspect python
No such element or plugin 'python'

~# rm ~/.gstreamer-0.10/*
~# gst-inspect python

Plugin Details:
  Name:            python
  Description:        loader for plugins written in python
  Filename:        /usr/lib/gstreamer-0.10/libgstpython.so
  Version:        0.10.22
  License:        LGPL
  Source module:    gst-python
  Source release date:    2011-10-29
  Binary package:    GStreamer Python Bindings
  Origin URL:        http://gstreamer.freedesktop.org


  0 features:

5) Now you may develop your element in python.  There are a few examples online.  Store them under /urs/lib/gstreamer-0.10/python/  and they should appear on the inspect. I don't know if this is supported yet on the 1.0 version.  

Michael

-----Original Message-----
From: Josh Doe <josh at joshdoe.com>
To: Discussion of the development of and with GStreamer <gstreamer-devel at lists.freedesktop.org>
Sent: Wed, 05 Feb 2014 11:03
Subject: Re: Embedding scripting language in a filter element

On Wed, Feb 5, 2014 at 9:53 AM, Michael Grüner
<michael.gruner at ridgerun.com> wrote:
> Yes, plugins written in python behave like any other. You can inspect them,
> use them with gst-launch or within your app.

It's very hard to come up with information about using Python with
GStreamer 1.0. This has some good info:
https://wiki.ubuntu.com/Novacut/GStreamer1.0

I could only come up with a single example of an element by searching
for "Gst.Element.register":
http://bazaar.launchpad.net/~jderose/+junk/gst-examples/view/head:/plugin-1.0

This asks exactly my question, but has no answer:
http://stackoverflow.com/q/17969041/403491

So as I understand it I install PyGObject
(http://sourceforge.net/projects/pygobjectwin32/), create my plugin as
in the example above, but then what? Where do I put the py/pyc/pyo
file? I can't find anything in GStreamer core about loading Python
plugins, so there must be another plugin that then searches for and
registers them.

Thanks for any help you can provide.
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