How to continuously monitor rhythmbox for track change using python

Question

Hi,

I want to monitor the change of track in Rhythmbox using python. I want to continuously check for change of track and execute a set of functions if the track is changed. I have written a piece of code which gets hold of the Rhythmbox interfaces from the dbus and gets the current track details. But this program has to be run manually to check for any change.

I am new to this and I would like to know how we can create a background process which continuously runs and checks Rhythmbox.

I dont want to make a Rhythmbox plugin(which rather would make my work simple) as I will be extending the application to listen to multiple music players.

Please suggest me what exactly I would have to do to achieve the functionality.

Answer 1

Something like:

from time import sleep

execute = True
while execute:
    your_function_call()
    sleep(30) # in seconds; prevent busy polling

Should work just fine. If that was hooked up to something that listened to signals (import signal) so that you could set execute to False when someone ctrl-c's the application, that'd be basically what you're after.

Otherwise, have a Google for daemonisation (which involves forking the process a couple of times); from memory, there's even a decent Python library now (which, from memory, requires 2.5/2.6 with statements) which would help make that side of things easier :).

Answer 2

Take a look at the Conky script here:

https://launchpad.net/~conkyhardcore/+archive/ppa/+files/conkyrhythmbox_2.12.tar.gz

That uses dbus to talk to rhythmbox, like so:

bus = dbus.SessionBus()
remote_object_shell = bus.get_object('org.gnome.Rhythmbox', '/org/gnome/Rhythmbox/Shell')
iface_shell = dbus.Interface(remote_object_shell, 'org.gnome.Rhythmbox.Shell')
remote_object_player = bus.get_object('org.gnome.Rhythmbox', '/org/gnome/Rhythmbox/Player')
iface_player = dbus.Interface(remote_object_player, 'org.gnome.Rhythmbox.Player')

You can call a number of functions on iface_player to get the required information. It looks like you'll have to poll from this example though. If you want to receive a message from dbus on track change you'll have to do that in a different way. This discusses from avenues to explore:

http://ubuntuforums.org/showthread.php?t=156706