1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
|
# Elements basics.py
#!/usr/bin/env python
"""
gst.Element basics, this is a modified script of Brandon Lewis
"""
# PiTiVi does this for you, but in any stand-alone gstreamer script you need
# to do this before anything else
import gobject
gobject.threads_init()
# import gst and gtk
import gst
import gtk
class NewElement(gst.Element):
""" A basic, buffer forwarding gstreamer element """
#here we register our plugin details
__gstdetails__ = (
"NewElement plugin",
"newelement.py",
"gst.Element, that passes a buffer from source to sink (a filter)",
"Stephen Griffiths <scgmk5@gmail.com>")
#source pad (template): we send buffers forward through here
_srctemplate = gst.PadTemplate ('src',
gst.PAD_SRC,
gst.PAD_ALWAYS,
gst.caps_new_any())
#sink pad (template): we receive buffers from our sink pad
_sinktemplate = gst.PadTemplate ('sink',
gst.PAD_SINK,
gst.PAD_ALWAYS,
gst.caps_new_any())
#register our pad templates
__gsttemplates__ = (_srctemplate, _sinktemplate)
def __init__(self, *args, **kwargs):
#initialise parent class
gst.Element.__init__(self, *args, **kwargs)
#source pad, outgoing data
self.srcpad = gst.Pad(self._srctemplate)
#sink pad, incoming data
self.sinkpad = gst.Pad(self._sinktemplate)
self.sinkpad.set_setcaps_function(self._sink_setcaps)
self.sinkpad.set_chain_function(self._sink_chain)
#make pads available
self.add_pad(self.srcpad)
self.add_pad(self.sinkpad)
def _sink_setcaps(self, pad, caps):
#we negotiate our capabilities here, this function is called
#as autovideosink accepts anything, we just say yes we can handle the
#incoming data
return True
def _sink_chain(self, pad, buf):
#this is where we do filtering
#and then push a buffer to the next element, returning a value saying
# it was either successful or not.
return self.srcpad.push(buf)
#here we register our class with glib, the c-based object system used by
#gstreamer
gobject.type_register(NewElement)
## this code creates the following pipeline, equivalent to
## gst-launch-0.10 videotestsrc ! videoscale ! ffmpegcolorspace !
### NewElement ! autovideosink
# first create individual gstreamer elements
source = gst.element_factory_make("videotestsrc")
print "making new element"
newElement = NewElement()
print "made new element"
vscale = gst.element_factory_make("videoscale")
cspace = gst.element_factory_make("ffmpegcolorspace")
vsink = gst.element_factory_make("autovideosink")
# create the pipeline
p = gst.Pipeline()
p.add(source, vscale, cspace, newElement,
vsink)
gst.element_link_many(source, vscale, cspace, newElement,
vsink)
# set pipeline to playback state
p.set_state(gst.STATE_PLAYING)
# start the main loop, pitivi does this already.
gtk.main()
|
