I'm working on a GStreamer-based program using Python and the GObject introspection bindings. I'm trying to build this pipeline:
videomixer name=mix ! autovideosink
uridecodebin uri=v4l2:///dev/video0 ! mix.
The pipeline works perfectly using gst-launch-1.0, but my Python program gives the errors:
(minimal.py:12168): GStreamer-CRITICAL **: gst_element_link_pads_full: assertion 'GST_IS_ELEMENT (src)' failed
on_error(): (GError('Internal data flow error.',), 'gstbasesrc.c(2865): gst_base_src_loop (): /GstPipeline:pipeline0/GstURIDecodeBin:uridecodebin0/GstV4l2Src:source:
streaming task paused, reason not-linked (-1)')
My code:
#!/usr/bin/python3
import gi
gi.require_version('Gst', '1.0')
from gi.repository import GObject, Gst, Gtk, GdkX11, GstVideo
GObject.threads_init()
Gst.init(None)
class Source:
def __init__(self, uri, pipeline, mixer):
self.uri = uri
self.pipeline = pipeline
self.mixer = mixer
self.src = Gst.ElementFactory.make('uridecodebin', None)
self.pipeline.add(self.src)
self.src.set_property('uri', uri)
self.src.connect('pad-added', self.on_pad_added, self.src, self.mixer)
def on_pad_added(self, element, pad, src, dest):
name = pad.query_caps(None).to_string()
print('on_pad_added:', name)
if name.startswith('video/'):
src.link(dest)
class Main:
def __init__(self):
self.window = Gtk.Window()
self.window.connect('destroy', self.quit)
self.window.set_default_size(1280, 720)
self.drawingarea = Gtk.DrawingArea()
self.window.add(self.drawingarea)
self.pipeline = Gst.Pipeline()
self.bus = self.pipeline.get_bus()
self.bus.add_signal_watch()
self.bus.connect('message::error', self.on_error)
self.bus.enable_sync_message_emission()
self.bus.connect('sync-message::element', self.on_sync_message)
self.mixer = Gst.ElementFactory.make('videomixer', None)
self.sink = Gst.ElementFactory.make('autovideosink', None)
self.pipeline.add(self.mixer)
self.pipeline.add(self.sink)
self.mixer.link(self.sink)
video = Source('v4l2:///dev/video0', self.pipeline, self.mixer)
def run(self):
self.window.show_all()
# You need to get the XID after window.show_all(). You shouldn't get it
# in the on_sync_message() handler because threading issues will cause
# segfaults there.
self.xid = self.drawingarea.get_property('window').get_xid()
self.pipeline.set_state(Gst.State.PLAYING)
Gtk.main()
def quit(self, window):
self.pipeline.set_state(Gst.State.NULL)
Gtk.main_quit()
def on_sync_message(self, bus, msg):
if msg.get_structure().get_name() == 'prepare-window-handle': msg.src.set_window_handle(self.xid)
def on_error(self, bus, msg):
print('on_error():', msg.parse_error())
main = Main()
main.run()
See Question&Answers more detail:
os 与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…