The "yes, you can write chain based elements in Python" commit.

Original commit message from CVS:
The "yes, you can write chain based elements in Python" commit.
AKA The "oh my, that is a slow rot13" commit.
AKA The "puddle from a stream of leaking bits" commit.

examples/gst/cp.py

@@ -28,9 +28,8 @@ from gobject import GObject
 def update(sender, *args):
    print sender.get_name(), args
 
-def main():
-   "A GStreamer based cp(1) with stats"
-   #gst_debug_set_categories(-1)
+def filter(filters):
+   "A GStreamer copy pipeline which can add arbitrary filters"
 
    if len(sys.argv) != 3:
       print 'usage: %s source dest' % (sys.argv[0])
@@ -45,28 +44,20 @@ def main():
       return -1
    filesrc.set_property('location', sys.argv[1])
 
-   stats = gst_elementfactory_make ('statistics', 'stats');
-   if not stats:
-      print 'could not find plugin \"statistics\"'
-      return -1
-   stats.set_property('silent', 0)
-   stats.set_property('buffer_update_freq', 1)
-   stats.set_property('update_on_eos', 1)
-   #GObject.connect(stats, 'update', update)
-
    filesink = gst_elementfactory_make ('disksink', 'sink')
    if not filesink:
       print 'could not find plugin \"disksink\"'
       return -1
    filesink.set_property('location', sys.argv[2])
 
+   elements = [filesrc] + filters + [filesink]
    #  add objects to the main pipeline
-   for e in (filesrc, stats, filesink):
+   for e in elements: 
       bin.add(e)
 
    # connect the elements
    previous = None
-   for e in (filesrc, stats, filesink):
+   for e in elements:
       if previous:
          previous.connect('src', e, 'sink')
       previous = e
@@ -81,6 +72,21 @@ def main():
 
    return 0
 
+def main():
+   "A GStreamer based cp(1) with stats"
+   gst_debug_set_categories(0)
+
+   stats = gst_elementfactory_make ('statistics', 'stats');
+   if not stats:
+      print 'could not find plugin \"statistics\"'
+      return -1
+   stats.set_property('silent', 0)
+   stats.set_property('buffer_update_freq', 1)
+   stats.set_property('update_on_eos', 1)
+   #GObject.connect(stats, 'update', update)
+
+   return filter([stats])
+
 if __name__ == '__main__':
    ret = main()
    sys.exit (ret)

examples/gst/dvdplay.py

@@ -43,12 +43,16 @@ class DVDPlay(object):
       print '***** a new pad %s was created' % pad.get_name()
       if pad.get_name()[:6] == 'video_':
          pad.connect(self.v_queue.get_pad('sink'))
+         #self.pipeline.set_state(STATE_PAUSED)
          self.pipeline.add(self.v_thread)
          self.v_thread.set_state(STATE_PLAYING)
+         #self.pipeline.set_state(STATE_PLAYING)
       elif pad.get_name() == 'private_stream_1.0':
          pad.connect(self.a_queue.get_pad('sink'))
+         #self.pipeline.set_state(STATE_PAUSED)
          self.pipeline.add(self.a_thread)
          self.a_thread.set_state(STATE_PLAYING);
+         #self.pipeline.set_state(STATE_PLAYING)
       else:
          print 'unknown pad: %s' % pad.get_name()
 

examples/gst/identity.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python2.2
+#
+# gst-python
+# Copyright (C) 2002 David I. Lehn
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Library General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Library General Public License for more details.
+#
+# You should have received a copy of the GNU Library General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+# 
+# Author: David I. Lehn <dlehn@vt.edu>
+#
+
+import sys
+from gstreamer import *
+import gobject
+from cp import filter
+
+class Identity(Element):
+   def __init__(self):
+      self.__gobject_init__()
+      self.sinkpad = gst_pad_new('sink', PAD_SINK)
+      self.add_pad(self.sinkpad)
+      self.sinkpad.set_chain_function(self.chain)
+      self.sinkpad.set_connect_function(self.pad_connect)
+
+      self.srcpad = gst_pad_new('src', PAD_SRC)
+      self.add_pad(self.srcpad)
+      self.srcpad.set_connect_function(self.pad_connect)
+
+   def get_bufferpool(self, pad):
+      print 'get_bufferpool:', self, pad
+      return self.srcpad.get_bufferpool()
+
+   def pad_connect(self, pad, caps):
+      print 'pad_connect:', self, pad, caps
+      return PAD_CONNECT_OK
+
+   def chain(self, pad, buf):
+      self.srcpad.push(buf)
+
+gobject.type_register(Identity)
+
+def main():
+   "A GStreamer Python subclassing example of an identity filter"
+   gst_debug_set_categories(0)
+
+   identity = Identity()
+   identity.set_name('identity')
+   if not identity:
+      print 'could not create \"Identity\" element'
+      return -1
+
+   return filter([identity])
+
+if __name__ == '__main__':
+   ret = main()
+   sys.exit (ret)

examples/gst/rot13.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python2.2
+#
+# gst-python
+# Copyright (C) 2002 David I. Lehn
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Library General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Library General Public License for more details.
+#
+# You should have received a copy of the GNU Library General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+# 
+# Author: David I. Lehn <dlehn@vt.edu>
+#
+
+import sys
+from gstreamer import *
+import gobject
+from identity import Identity
+from cp import filter
+
+class Rot13(Identity):
+   def chain(self, pad, buf):
+      # override Identity's chain
+      data = gst_buffer_get_data(buf)
+      data2 = ''
+      # waste cycles
+      for c in data:
+         if c.isalpha():
+            if c.islower():
+               a = 'a'
+            else:
+               a = 'A'
+            c = chr((((ord(c) - ord(a)) + 13) % 26) + ord(a))
+         data2 = data2 + c
+      newbuf = gst_buffer_new()
+      gst_buffer_set_data(newbuf, data2)
+      self.srcpad.push(newbuf)
+
+gobject.type_register(Rot13)
+
+def main():
+   "A GStreamer Python subclassing example of a rot13 filter"
+   gst_debug_set_categories(0)
+
+   rot13 = Rot13()
+   rot13.set_name('rot13')
+   if not rot13:
+      print 'could not create \"Rot13\" element'
+      return -1
+
+   return filter([rot13])
+
+if __name__ == '__main__':
+   ret = main()
+   sys.exit (ret)

examples/gstreamer/cp.py

@@ -28,9 +28,8 @@ from gobject import GObject
 def update(sender, *args):
    print sender.get_name(), args
 
-def main():
-   "A GStreamer based cp(1) with stats"
-   #gst_debug_set_categories(-1)
+def filter(filters):
+   "A GStreamer copy pipeline which can add arbitrary filters"
 
    if len(sys.argv) != 3:
       print 'usage: %s source dest' % (sys.argv[0])
@@ -45,28 +44,20 @@ def main():
       return -1
    filesrc.set_property('location', sys.argv[1])
 
-   stats = gst_elementfactory_make ('statistics', 'stats');
-   if not stats:
-      print 'could not find plugin \"statistics\"'
-      return -1
-   stats.set_property('silent', 0)
-   stats.set_property('buffer_update_freq', 1)
-   stats.set_property('update_on_eos', 1)
-   #GObject.connect(stats, 'update', update)
-
    filesink = gst_elementfactory_make ('disksink', 'sink')
    if not filesink:
       print 'could not find plugin \"disksink\"'
       return -1
    filesink.set_property('location', sys.argv[2])
 
+   elements = [filesrc] + filters + [filesink]
    #  add objects to the main pipeline
-   for e in (filesrc, stats, filesink):
+   for e in elements: 
       bin.add(e)
 
    # connect the elements
    previous = None
-   for e in (filesrc, stats, filesink):
+   for e in elements:
       if previous:
          previous.connect('src', e, 'sink')
       previous = e
@@ -81,6 +72,21 @@ def main():
 
    return 0
 
+def main():
+   "A GStreamer based cp(1) with stats"
+   gst_debug_set_categories(0)
+
+   stats = gst_elementfactory_make ('statistics', 'stats');
+   if not stats:
+      print 'could not find plugin \"statistics\"'
+      return -1
+   stats.set_property('silent', 0)
+   stats.set_property('buffer_update_freq', 1)
+   stats.set_property('update_on_eos', 1)
+   #GObject.connect(stats, 'update', update)
+
+   return filter([stats])
+
 if __name__ == '__main__':
    ret = main()
    sys.exit (ret)

examples/gstreamer/dvdplay.py

@@ -43,12 +43,16 @@ class DVDPlay(object):
       print '***** a new pad %s was created' % pad.get_name()
       if pad.get_name()[:6] == 'video_':
          pad.connect(self.v_queue.get_pad('sink'))
+         #self.pipeline.set_state(STATE_PAUSED)
          self.pipeline.add(self.v_thread)
          self.v_thread.set_state(STATE_PLAYING)
+         #self.pipeline.set_state(STATE_PLAYING)
       elif pad.get_name() == 'private_stream_1.0':
          pad.connect(self.a_queue.get_pad('sink'))
+         #self.pipeline.set_state(STATE_PAUSED)
          self.pipeline.add(self.a_thread)
          self.a_thread.set_state(STATE_PLAYING);
+         #self.pipeline.set_state(STATE_PLAYING)
       else:
          print 'unknown pad: %s' % pad.get_name()
 

examples/gstreamer/identity.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python2.2
+#
+# gst-python
+# Copyright (C) 2002 David I. Lehn
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Library General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Library General Public License for more details.
+#
+# You should have received a copy of the GNU Library General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+# 
+# Author: David I. Lehn <dlehn@vt.edu>
+#
+
+import sys
+from gstreamer import *
+import gobject
+from cp import filter
+
+class Identity(Element):
+   def __init__(self):
+      self.__gobject_init__()
+      self.sinkpad = gst_pad_new('sink', PAD_SINK)
+      self.add_pad(self.sinkpad)
+      self.sinkpad.set_chain_function(self.chain)
+      self.sinkpad.set_connect_function(self.pad_connect)
+
+      self.srcpad = gst_pad_new('src', PAD_SRC)
+      self.add_pad(self.srcpad)
+      self.srcpad.set_connect_function(self.pad_connect)
+
+   def get_bufferpool(self, pad):
+      print 'get_bufferpool:', self, pad
+      return self.srcpad.get_bufferpool()
+
+   def pad_connect(self, pad, caps):
+      print 'pad_connect:', self, pad, caps
+      return PAD_CONNECT_OK
+
+   def chain(self, pad, buf):
+      self.srcpad.push(buf)
+
+gobject.type_register(Identity)
+
+def main():
+   "A GStreamer Python subclassing example of an identity filter"
+   gst_debug_set_categories(0)
+
+   identity = Identity()
+   identity.set_name('identity')
+   if not identity:
+      print 'could not create \"Identity\" element'
+      return -1
+
+   return filter([identity])
+
+if __name__ == '__main__':
+   ret = main()
+   sys.exit (ret)

examples/gstreamer/rot13.py

@@ -0,0 +1,64 @@
+#!/usr/bin/env python2.2
+#
+# gst-python
+# Copyright (C) 2002 David I. Lehn
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Library General Public
+# License as published by the Free Software Foundation; either
+# version 2 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Library General Public License for more details.
+#
+# You should have received a copy of the GNU Library General Public
+# License along with this library; if not, write to the
+# Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+# 
+# Author: David I. Lehn <dlehn@vt.edu>
+#
+
+import sys
+from gstreamer import *
+import gobject
+from identity import Identity
+from cp import filter
+
+class Rot13(Identity):
+   def chain(self, pad, buf):
+      # override Identity's chain
+      data = gst_buffer_get_data(buf)
+      data2 = ''
+      # waste cycles
+      for c in data:
+         if c.isalpha():
+            if c.islower():
+               a = 'a'
+            else:
+               a = 'A'
+            c = chr((((ord(c) - ord(a)) + 13) % 26) + ord(a))
+         data2 = data2 + c
+      newbuf = gst_buffer_new()
+      gst_buffer_set_data(newbuf, data2)
+      self.srcpad.push(newbuf)
+
+gobject.type_register(Rot13)
+
+def main():
+   "A GStreamer Python subclassing example of a rot13 filter"
+   gst_debug_set_categories(0)
+
+   rot13 = Rot13()
+   rot13.set_name('rot13')
+   if not rot13:
+      print 'could not create \"Rot13\" element'
+      return -1
+
+   return filter([rot13])
+
+if __name__ == '__main__':
+   ret = main()
+   sys.exit (ret)

gst/gst.defs

@@ -3457,3 +3457,19 @@
 )
 
 
+(define-function gst_buffer_get_data
+  (c-name "gst_buffer_get_data")
+  (return-type "char*")
+  (parameters
+    '("GstBuffer*" "buf")
+  )
+)
+
+(define-function gst_buffer_set_data
+  (c-name "gst_buffer_set_data")
+  (return-type "none")
+  (parameters
+    '("GstBuffer*" "buf")
+    '("char*" "data")
+  )
+)

gst/gstreamer.defs

@@ -3457,3 +3457,19 @@
 )
 
 
+(define-function gst_buffer_get_data
+  (c-name "gst_buffer_get_data")
+  (return-type "char*")
+  (parameters
+    '("GstBuffer*" "buf")
+  )
+)
+
+(define-function gst_buffer_set_data
+  (c-name "gst_buffer_set_data")
+  (return-type "none")
+  (parameters
+    '("GstBuffer*" "buf")
+    '("char*" "data")
+  )
+)

gst/gstreamer.override

@@ -28,6 +28,38 @@ headers
 #include "pygobject.h"
 #include <gst/gst.h>
 
+typedef struct {
+	PyGObject *pad;
+	PyObject *connect_function;
+	PyObject *chain_function;
+} PyGstPadPrivate;
+
+static PyGstPadPrivate*
+pad_private(GstPad *pad)
+{
+	return (PyGstPadPrivate*)gst_pad_get_element_private(pad);
+}
+	
+static PyGstPadPrivate*
+py_pad_private(PyGObject *pad)
+{
+	PyGstPadPrivate *private;
+	GstPad *gpad;
+
+	gpad = (GstPad*)pygobject_get(pad);
+	private = (PyGstPadPrivate*)gst_pad_get_element_private(gpad);
+	if (private == NULL) {
+		/* FIXME need to free this somewhere */
+		private = g_new0(PyGstPadPrivate, 1);
+		Py_INCREF(pad);
+		private->pad = pad;
+		gst_pad_set_element_private(gpad, private);
+	}
+	return private;
+}
+	
+%%
+modulename gstreamer
 %%
 import gobject.GObject as PyGObject_Type
 %%
@@ -35,5 +67,222 @@ ignore-glob
  _*
  gstreamer_*init
  *_get_type
- 
 %%
+override gst_pad_set_connect_function kwargs
+
+static GstPadConnectReturn
+call_connect_function (GstPad *pad, GstCaps *caps)
+{
+	PyObject *function;
+	PyObject *retval;
+	
+	function = pad_private(pad)->connect_function;
+	
+	retval = (PyObject*)PyObject_CallFunction (function,
+			"OO",
+			pad_private(pad)->pad,
+			PyCObject_FromVoidPtr (caps, NULL));
+
+	if (PyErr_Occurred ()) {
+		PyErr_Print ();
+		return GST_PAD_CONNECT_REFUSED;
+	}
+
+	return PyInt_AsLong(retval);
+}
+
+static PyObject*
+_wrap_gst_pad_set_connect_function (PyGObject *self,
+		PyObject  *args,
+		PyObject  *kwargs)
+{
+	static char *kwlist[] = { "connect_function", NULL };
+	PyObject *connect_function;
+	GstPad *pad;
+	
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+	                                 "O:GstPad.set_connect_funcion",
+					 kwlist,
+					 &connect_function)) {
+		return NULL;
+	}
+	
+	if (!PyCallable_Check(connect_function)) {
+		PyErr_SetString(PyExc_TypeError, "connect_function not callable");
+		return NULL;
+	}
+	
+	Py_INCREF(connect_function);
+	py_pad_private(self)->connect_function = connect_function;
+	pad = (GstPad*)pygobject_get(self);
+	gst_pad_set_connect_function(pad, call_connect_function);
+
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+%%
+override gst_pad_set_chain_function kwargs
+
+static void
+call_chain_function (GstPad *pad, GstBuffer *buf)
+{
+	PyObject *function;
+	
+	function = pad_private(pad)->chain_function;
+	
+	PyObject_CallFunction (function,
+			"OO", 
+			pad_private(pad)->pad,
+			PyCObject_FromVoidPtr (buf, NULL));
+
+	if (PyErr_Occurred ()) {
+		PyErr_Print ();
+		return;
+	}
+}
+
+static PyObject*
+_wrap_gst_pad_set_chain_function (PyGObject *self,
+				   PyObject  *args,
+				   PyObject  *kwargs)
+{
+	static char *kwlist[] = { "chain_function", NULL };
+	PyObject *chain_function;
+	GstPad *pad;
+	
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+	                                 "O:GstPad.set_chain_funcion",
+					 kwlist,
+					 &chain_function)) {
+		return NULL;
+	}
+	
+	if (!PyCallable_Check(chain_function)) {
+		PyErr_SetString(PyExc_TypeError, "chain_function not callable");
+		return NULL;
+	}
+	
+	Py_INCREF(chain_function);
+	py_pad_private(self)->chain_function = chain_function;
+	pad = (GstPad*)pygobject_get(self);
+	gst_pad_set_chain_function(pad, call_chain_function);
+
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+%%
+override gst_pad_push kwargs
+
+static PyObject*
+_wrap_gst_pad_push (PyGObject *self,
+		PyObject  *args,
+		PyObject  *kwargs)
+{
+	static char *kwlist[] = { "buffer", NULL };
+	PyObject *pybuf;
+	GstBuffer *buf;
+	GstPad *pad;
+	
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+	                                 "O:GstPad.push",
+					 kwlist,
+					 &pybuf)) {
+		return NULL;
+	}
+	
+	if (!PyCObject_Check(pybuf)) {
+		PyErr_SetString(PyExc_TypeError, "push expecting a PyCObject");
+		return NULL;
+	}
+	
+	pad = (GstPad*)pygobject_get(self);
+	buf = (GstBuffer*)PyCObject_AsVoidPtr(pybuf);
+	gst_pad_push(pad, buf);
+
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+%%
+override gst_buffer_get_data
+
+static PyObject*
+_wrap_gst_buffer_get_data (PyObject *self,
+		PyObject  *args)
+{
+	PyObject *pybuf;
+	GstBuffer *buf;
+	
+	if (!PyArg_ParseTuple(args,
+				"O:GstBuffer:get_data",
+				&pybuf)) {
+		return NULL;
+	}
+	
+	if (!PyCObject_Check(pybuf)) {
+		PyErr_SetString(PyExc_TypeError, "get_data expecting a PyCObject");
+		return NULL;
+	}
+	
+	buf = (GstBuffer*)PyCObject_AsVoidPtr(pybuf);
+
+	return PyString_FromStringAndSize(
+			GST_BUFFER_DATA(buf),
+			GST_BUFFER_SIZE(buf));
+}
+%%
+override gst_buffer_set_data
+
+static PyObject*
+_wrap_gst_buffer_set_data (PyObject *self,
+		PyObject  *args)
+{
+	PyObject *pybuf;
+	PyObject *data;
+	GstBuffer *buf;
+	
+	if (!PyArg_ParseTuple(args,
+				"OO:GstBuffer:set_data",
+				&pybuf, &data)) {
+		return NULL;
+	}
+	
+	if (!PyCObject_Check(pybuf)) {
+		PyErr_SetString(PyExc_TypeError, "set_data expecting a PyCObject");
+		return NULL;
+	}
+	if (!PyString_Check(data)) {
+		PyErr_SetString(PyExc_TypeError, "set_data expecting a string");
+		return NULL;
+	}
+	if (GST_BUFFER_FLAGS(buf) & GST_BUFFER_READONLY) {
+		PyErr_SetString(PyExc_TypeError, "set_data can't use a READONLY buffer");
+		return NULL;
+	}
+	
+	buf = (GstBuffer*)PyCObject_AsVoidPtr(pybuf);
+	GST_BUFFER_SIZE(buf) = PyString_Size(data);
+	GST_BUFFER_DATA(buf) = g_new0(char, GST_BUFFER_SIZE(buf));
+
+	memcpy(GST_BUFFER_DATA(buf),
+			PyString_AsString(data),
+			PyString_Size(data));
+
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+%%
+override gst_buffer_new
+
+static PyObject*
+_wrap_gst_buffer_new (PyObject *self,
+		PyObject  *args)
+{
+	GstBuffer *newbuf;
+	
+	if (!PyArg_ParseTuple(args, ":GstBuffer:set_data")) {
+		return NULL;
+	}
+	
+	newbuf = gst_buffer_new();
+	return PyCObject_FromVoidPtr (newbuf, NULL);
+}

gstreamer/gst.defs

@@ -3457,3 +3457,19 @@
 )
 
 
+(define-function gst_buffer_get_data
+  (c-name "gst_buffer_get_data")
+  (return-type "char*")
+  (parameters
+    '("GstBuffer*" "buf")
+  )
+)
+
+(define-function gst_buffer_set_data
+  (c-name "gst_buffer_set_data")
+  (return-type "none")
+  (parameters
+    '("GstBuffer*" "buf")
+    '("char*" "data")
+  )
+)

gstreamer/gstreamer.defs

@@ -3457,3 +3457,19 @@
 )
 
 
+(define-function gst_buffer_get_data
+  (c-name "gst_buffer_get_data")
+  (return-type "char*")
+  (parameters
+    '("GstBuffer*" "buf")
+  )
+)
+
+(define-function gst_buffer_set_data
+  (c-name "gst_buffer_set_data")
+  (return-type "none")
+  (parameters
+    '("GstBuffer*" "buf")
+    '("char*" "data")
+  )
+)

gstreamer/gstreamer.override

@@ -28,6 +28,38 @@ headers
 #include "pygobject.h"
 #include <gst/gst.h>
 
+typedef struct {
+	PyGObject *pad;
+	PyObject *connect_function;
+	PyObject *chain_function;
+} PyGstPadPrivate;
+
+static PyGstPadPrivate*
+pad_private(GstPad *pad)
+{
+	return (PyGstPadPrivate*)gst_pad_get_element_private(pad);
+}
+	
+static PyGstPadPrivate*
+py_pad_private(PyGObject *pad)
+{
+	PyGstPadPrivate *private;
+	GstPad *gpad;
+
+	gpad = (GstPad*)pygobject_get(pad);
+	private = (PyGstPadPrivate*)gst_pad_get_element_private(gpad);
+	if (private == NULL) {
+		/* FIXME need to free this somewhere */
+		private = g_new0(PyGstPadPrivate, 1);
+		Py_INCREF(pad);
+		private->pad = pad;
+		gst_pad_set_element_private(gpad, private);
+	}
+	return private;
+}
+	
+%%
+modulename gstreamer
 %%
 import gobject.GObject as PyGObject_Type
 %%
@@ -35,5 +67,222 @@ ignore-glob
  _*
  gstreamer_*init
  *_get_type
- 
 %%
+override gst_pad_set_connect_function kwargs
+
+static GstPadConnectReturn
+call_connect_function (GstPad *pad, GstCaps *caps)
+{
+	PyObject *function;
+	PyObject *retval;
+	
+	function = pad_private(pad)->connect_function;
+	
+	retval = (PyObject*)PyObject_CallFunction (function,
+			"OO",
+			pad_private(pad)->pad,
+			PyCObject_FromVoidPtr (caps, NULL));
+
+	if (PyErr_Occurred ()) {
+		PyErr_Print ();
+		return GST_PAD_CONNECT_REFUSED;
+	}
+
+	return PyInt_AsLong(retval);
+}
+
+static PyObject*
+_wrap_gst_pad_set_connect_function (PyGObject *self,
+		PyObject  *args,
+		PyObject  *kwargs)
+{
+	static char *kwlist[] = { "connect_function", NULL };
+	PyObject *connect_function;
+	GstPad *pad;
+	
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+	                                 "O:GstPad.set_connect_funcion",
+					 kwlist,
+					 &connect_function)) {
+		return NULL;
+	}
+	
+	if (!PyCallable_Check(connect_function)) {
+		PyErr_SetString(PyExc_TypeError, "connect_function not callable");
+		return NULL;
+	}
+	
+	Py_INCREF(connect_function);
+	py_pad_private(self)->connect_function = connect_function;
+	pad = (GstPad*)pygobject_get(self);
+	gst_pad_set_connect_function(pad, call_connect_function);
+
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+%%
+override gst_pad_set_chain_function kwargs
+
+static void
+call_chain_function (GstPad *pad, GstBuffer *buf)
+{
+	PyObject *function;
+	
+	function = pad_private(pad)->chain_function;
+	
+	PyObject_CallFunction (function,
+			"OO", 
+			pad_private(pad)->pad,
+			PyCObject_FromVoidPtr (buf, NULL));
+
+	if (PyErr_Occurred ()) {
+		PyErr_Print ();
+		return;
+	}
+}
+
+static PyObject*
+_wrap_gst_pad_set_chain_function (PyGObject *self,
+				   PyObject  *args,
+				   PyObject  *kwargs)
+{
+	static char *kwlist[] = { "chain_function", NULL };
+	PyObject *chain_function;
+	GstPad *pad;
+	
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+	                                 "O:GstPad.set_chain_funcion",
+					 kwlist,
+					 &chain_function)) {
+		return NULL;
+	}
+	
+	if (!PyCallable_Check(chain_function)) {
+		PyErr_SetString(PyExc_TypeError, "chain_function not callable");
+		return NULL;
+	}
+	
+	Py_INCREF(chain_function);
+	py_pad_private(self)->chain_function = chain_function;
+	pad = (GstPad*)pygobject_get(self);
+	gst_pad_set_chain_function(pad, call_chain_function);
+
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+%%
+override gst_pad_push kwargs
+
+static PyObject*
+_wrap_gst_pad_push (PyGObject *self,
+		PyObject  *args,
+		PyObject  *kwargs)
+{
+	static char *kwlist[] = { "buffer", NULL };
+	PyObject *pybuf;
+	GstBuffer *buf;
+	GstPad *pad;
+	
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs,
+	                                 "O:GstPad.push",
+					 kwlist,
+					 &pybuf)) {
+		return NULL;
+	}
+	
+	if (!PyCObject_Check(pybuf)) {
+		PyErr_SetString(PyExc_TypeError, "push expecting a PyCObject");
+		return NULL;
+	}
+	
+	pad = (GstPad*)pygobject_get(self);
+	buf = (GstBuffer*)PyCObject_AsVoidPtr(pybuf);
+	gst_pad_push(pad, buf);
+
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+%%
+override gst_buffer_get_data
+
+static PyObject*
+_wrap_gst_buffer_get_data (PyObject *self,
+		PyObject  *args)
+{
+	PyObject *pybuf;
+	GstBuffer *buf;
+	
+	if (!PyArg_ParseTuple(args,
+				"O:GstBuffer:get_data",
+				&pybuf)) {
+		return NULL;
+	}
+	
+	if (!PyCObject_Check(pybuf)) {
+		PyErr_SetString(PyExc_TypeError, "get_data expecting a PyCObject");
+		return NULL;
+	}
+	
+	buf = (GstBuffer*)PyCObject_AsVoidPtr(pybuf);
+
+	return PyString_FromStringAndSize(
+			GST_BUFFER_DATA(buf),
+			GST_BUFFER_SIZE(buf));
+}
+%%
+override gst_buffer_set_data
+
+static PyObject*
+_wrap_gst_buffer_set_data (PyObject *self,
+		PyObject  *args)
+{
+	PyObject *pybuf;
+	PyObject *data;
+	GstBuffer *buf;
+	
+	if (!PyArg_ParseTuple(args,
+				"OO:GstBuffer:set_data",
+				&pybuf, &data)) {
+		return NULL;
+	}
+	
+	if (!PyCObject_Check(pybuf)) {
+		PyErr_SetString(PyExc_TypeError, "set_data expecting a PyCObject");
+		return NULL;
+	}
+	if (!PyString_Check(data)) {
+		PyErr_SetString(PyExc_TypeError, "set_data expecting a string");
+		return NULL;
+	}
+	if (GST_BUFFER_FLAGS(buf) & GST_BUFFER_READONLY) {
+		PyErr_SetString(PyExc_TypeError, "set_data can't use a READONLY buffer");
+		return NULL;
+	}
+	
+	buf = (GstBuffer*)PyCObject_AsVoidPtr(pybuf);
+	GST_BUFFER_SIZE(buf) = PyString_Size(data);
+	GST_BUFFER_DATA(buf) = g_new0(char, GST_BUFFER_SIZE(buf));
+
+	memcpy(GST_BUFFER_DATA(buf),
+			PyString_AsString(data),
+			PyString_Size(data));
+
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+%%
+override gst_buffer_new
+
+static PyObject*
+_wrap_gst_buffer_new (PyObject *self,
+		PyObject  *args)
+{
+	GstBuffer *newbuf;
+	
+	if (!PyArg_ParseTuple(args, ":GstBuffer:set_data")) {
+		return NULL;
+	}
+	
+	newbuf = gst_buffer_new();
+	return PyCObject_FromVoidPtr (newbuf, NULL);
+}