from mopidy.mixers import BaseMixer

class GStreamerSoftwareMixer(BaseMixer):
    """Mixer which uses GStreamer to control volume in software."""

    def __init__(self, *args, **kwargs):
        super(GStreamerSoftwareMixer, self).__init__(*args, **kwargs)

    def _get_volume(self):
        return self.backend.output.get_volume()

    def _set_volume(self, volume):
        self.backend.output.set_volume(volume)

import multiprocessing

from mopidy.mixers import BaseMixer
from mopidy.utils.process import pickle_connection

class GStreamerSoftwareMixer(BaseMixer):
    """Mixer which uses GStreamer to control volume in software."""

    def __init__(self, *args, **kwargs):
        super(GStreamerSoftwareMixer, self).__init__(*args, **kwargs)

    def _get_volume(self):
        my_end, other_end = multiprocessing.Pipe()
        self.backend.output_queue.put({
            'command': 'get_volume',
            'reply_to': pickle_connection(other_end),
        })
        my_end.poll(None)
        return my_end.recv()

    def _set_volume(self, volume):
        self.backend.output_queue.put({
            'command': 'set_volume',
            'volume': volume,
        })

--- 
+++ 
@@ -1,7 +1,4 @@
-import multiprocessing
-
 from mopidy.mixers import BaseMixer
-from mopidy.utils.process import pickle_connection
 
 class GStreamerSoftwareMixer(BaseMixer):
     """Mixer which uses GStreamer to control volume in software."""
@@ -10,16 +7,7 @@
         super(GStreamerSoftwareMixer, self).__init__(*args, **kwargs)
 
     def _get_volume(self):
-        my_end, other_end = multiprocessing.Pipe()
-        self.backend.output_queue.put({
-            'command': 'get_volume',
-            'reply_to': pickle_connection(other_end),
-        })
-        my_end.poll(None)
-        return my_end.recv()
+        return self.backend.output.get_volume()
 
     def _set_volume(self, volume):
-        self.backend.output_queue.put({
-            'command': 'set_volume',
-            'volume': volume,
-        })
+        self.backend.output.set_volume(volume)
Update GStreamer software mixer to use new output API
