Gstreamer python get bus message reconnection

Question

I have Tkinter application with some gstreamer pipelines to display different streams and I'd like to detect when one of the pipelines loses connection. I tried with bus messages but it seems to me that it doesn't post the message at all. I created a widget to manage the gstreamer logic and the code for the widget is the following.

from tkinter.ttk import Widget

import gi

# Needed for set_window_handle():
gi.require_version('GstVideo', '1.0')
gi.require_version('Gst', '1.0')
from gi.repository import Gst, GstVideo


class GstWidget(Widget):
    def __init__(self, gst_launch_string, x, y, width, height, master=None, **kw):
        super(GstWidget, self).__init__(master, 'frame', **kw)

        self.place(x=x, y=y, width=width, height=height)

        self.frame_id = self.winfo_id()

        self.player = Gst.parse_launch(gst_launch_string)
        self.player.set_state(Gst.State.PLAYING)

        self.bus = self.player.get_bus()
        self.bus.add_signal_watch()
        self.bus.connect('message::error', self.on_error)
        self.bus.connect('message::state-changed', self.on_status_changed)
        self.bus.connect('message::eos', self.on_eos)
        self.bus.connect('message::info', self.on_info)
        self.bus.enable_sync_message_emission()
        self.bus.connect('sync-message::element', self.set_frame_handle)

    def on_status_changed(self, bus, message):
        print('status_changed message -> {}'.format(message))

    def on_eos(self, bus, message):
        print('eos message -> {}'.format(message))

    def on_info(self, bus, message):
        print('info message -> {}'.format(message))

    def on_error(self, bus, message):
        print('error message -> {}'.format(message.parse_error()))

    def play(self):
        print('Current state of my pipeline is {}'.format(self.player.current_state))
        print('setting pipeline state to playing')
        self.player.set_state(Gst.State.PLAYING)

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

    def is_playing(self):
        print('\t\t{}'.format(self.player.current_state))
        return self.player.current_state is not Gst.State.PLAYING

    def set_frame_handle(self, bus, message):
        if message.get_structure().get_name() == 'prepare-window-handle':
            frame = message.src
            frame.set_property('force-aspect-ratio', True)
            frame.set_window_handle(self.frame_id)

Can anyone point to me where I'm wrong? I've put breakpoints to all events and also it's not printing anything from the events that I'd like to watch. And also can you point me if there's any way to retry to connect the pipeline on a lost connection?

Answer 1

I finally figured it out. The "problem" was with the tkinter mainloop. Since GStreamer depends heavily on Glib and tkinter doesn't use the glib mainloop I had to create one like suggested by @jldupont at tkinter integration with glib mainloop