Python gi.repository Gst.ElementFactory.make返回None？

Question

我想從gi.repository中使用Gst來代替常規gst。 https://wiki.ubuntu.com/Novacut/GStreamer1.0這裏是指南。 這是代碼：

#!/usr/bin/env python 
from gi.repository import GObject 
from gi.repository import GLib 
from gi.repository import Gtk 
from gi.repository import Gst 
Gst.init(None) 
class PlaybackInterface: 

    def __init__(self): 
    self.playing = False 

    # A free example sound track 
    self.uri = "http://cdn02.cdn.gorillavsbear.net/wp-content/uploads/2012/10/GORILLA-VS-BEAR-OCTOBER-2012.mp3" 

    # GTK window and widgets 
    self.window = Gtk.Window() 
    self.window.set_size_request(300,50) 

    vbox = Gtk.Box(Gtk.Orientation.HORIZONTAL, 0) 
    vbox.set_margin_top(3) 
    vbox.set_margin_bottom(3) 
    self.window.add(vbox) 

    self.playButtonImage = Gtk.Image() 
    self.playButtonImage.set_from_stock("gtk-media-play", Gtk.IconSize.BUTTON) 
    self.playButton = Gtk.Button.new() 
    self.playButton.add(self.playButtonImage) 
    self.playButton.connect("clicked", self.playToggled) 
    Gtk.Box.pack_start(vbox, self.playButton, False, False, 0) 

    self.slider = Gtk.HScale() 
    self.slider.set_margin_left(6) 
    self.slider.set_margin_right(6) 
    self.slider.set_draw_value(False) 
    self.slider.set_range(0, 100) 
    self.slider.set_increments(1, 10) 

    Gtk.Box.pack_start(vbox, self.slider, True, True, 0) 

    self.label = Gtk.Label(label='0:00') 
    self.label.set_margin_left(6) 
    self.label.set_margin_right(6) 
    Gtk.Box.pack_start(vbox, self.label, False, False, 0) 

    self.window.show_all() 

     # GStreamer Setup 
     Gst.init_check(None) 
     self.IS_GST010 = Gst.version()[0] == 0 
    self.player = Gst.ElementFactory.make("playbin2", "player") 
    fakesink = Gst.ElementFactory.make("fakesink", "fakesink") 
    self.player.set_property("video-sink", fakesink) 
    bus = self.player.get_bus() 
    #bus.add_signal_watch_full() 
    bus.connect("message", self.on_message) 
    self.player.connect("about-to-finish", self.on_finished) 

    def on_message(self, bus, message): 
    t = message.type 
    if t == Gst.Message.EOS: 
     self.player.set_state(Gst.State.NULL) 
     self.playing = False 
    elif t == Gst.Message.ERROR: 
     self.player.set_state(Gst.State.NULL) 
     err, debug = message.parse_error() 
     print "Error: %s" % err, debug 
     self.playing = False 

    self.updateButtons() 

    def on_finished(self, player): 
    self.playing = False 
     self.slider.set_value(0) 
    self.label.set_text("0:00") 
     self.updateButtons() 

    def play(self): 
    self.player.set_property("uri", self.uri) 
    self.player.set_state(Gst.State.PLAYING) 
    GObject.timeout_add(1000, self.updateSlider) 

    def stop(self): 
    self.player.set_state(Gst.State.NULL) 

    def playToggled(self, w): 
     self.slider.set_value(0) 
    self.label.set_text("0:00") 

    if(self.playing == False): 
     self.play() 
    else: 
     self.stop() 

    self.playing=not(self.playing) 
    self.updateButtons() 

    def updateSlider(self): 
    if(self.playing == False): 
     return False # cancel timeout 

    try: 
     if self.IS_GST010: 
      nanosecs = self.player.query_position(Gst.Format.TIME)[2] 
      duration_nanosecs = self.player.query_duration(Gst.Format.TIME)[2] 
     else: 
      nanosecs = self.player.query_position(Gst.Format.TIME)[1] 
      duration_nanosecs = self.player.query_duration(Gst.Format.TIME)[1] 

     # block seek handler so we don't seek when we set_value() 
     # self.slider.handler_block_by_func(self.on_slider_change) 

      duration = float(duration_nanosecs)/Gst.SECOND 
     position = float(nanosecs)/Gst.SECOND 
     self.slider.set_range(0, duration) 
     self.slider.set_value(position) 
      self.label.set_text ("%d" % (position/60) + ":%02d" % (position % 60)) 

     #self.slider.handler_unblock_by_func(self.on_slider_change) 

    except Exception as e: 
     # pipeline must not be ready and does not know position 
     print e 
     pass 

    return True 

    def updateButtons(self): 
     if(self.playing == False): 
      self.playButtonImage.set_from_stock("gtk-media-play", Gtk.IconSize.BUTTON) 
     else: 
      self.playButtonImage.set_from_stock("gtk-media-stop", Gtk.IconSize.BUTTON) 

if __name__ == "__main__": 
    PlaybackInterface() 
    Gtk.main() 

但我有：

Traceback (most recent call last): 
    File "./xy", line 134, in <module> 
    PlaybackInterface() 
    File "./xy", line 52, in __init__ 
    self.player.set_property("video-sink", fakesink) 
AttributeError: 'NoneType' object has no attribute 'set_property' 

錯誤。如何使用Gst.ElementFactory.make？它返回None？

Answer 1

使用playbin而不是playbin2。

self.player = Gst.ElementFactory.make("playbin", "player") 

因爲Gst-1.0中沒有playbin2元素，所以ElementFactory.make不返回任何值。 Playbin2在Gst-0.1中