[WIP] Add GStreamerOutput

mopidy/outputs/gstreamer.py

@@ -0,0 +1,130 @@
+import gobject
+
+import pygst
+pygst.require('0.10')
+
+import gst
+import logging
+
+from mopidy.process import BaseProcess
+
+logger = logging.getLogger('mopidy.outputs.gstreamer')
+
+class GStreamerOutput(object):
+    """
+    Audio output through GStreamer.
+
+    Starts the :class:`GStreamerProcess`.
+    """
+
+    def __init__(self, core_queue):
+        process = GStreamerProcess(core_queue)
+        process.start()
+
+class GStreamerProcess(BaseProcess):
+    """
+    A process for all work related to GStreamer.
+
+    The main loop polls for events from both Mopidy and GStreamer.
+    """
+
+    def __init__(self, core_queue):
+        self.core_queue = core_queue
+
+        # See http://www.jejik.com/articles/2007/01/
+        # python-gstreamer_threading_and_the_main_loop/ for details.
+        gobject.threads_init()
+        self.gobject_context = gobject.MainLoop().get_context()
+
+        # A pipeline consisting of many elements
+        self.gst_pipeline = gst.Pipeline("pipeline")
+
+        # Setup bus and message processor
+        self.gst_bus = self.gst_pipeline.get_bus()
+        self.gst_bus.add_signal_watch()
+        self.gst_bus_id = self.gst_bus.connect('message', self.process_message)
+
+        # Bin for playing audio URIs
+        self.gst_uri_src = gst.element_factory_make('uridecodebin', 'uri_src')
+        self.gst_pipeline.add(self.gst_uri_src)
+
+        # Bin for playing audio data
+        self.gst_data_src = gst.element_factory_make('appsrc', 'data_src')
+        self.gst_pipeline.add(self.gst_data_src)
+
+        # Volume filter
+        self.gst_volume = gst.element_factory_make('volume', 'volume')
+        self.gst_pipeline.add(self.gst_volume)
+
+        # Audio output sink
+        self.gst_sink = gst.element_factory_make('autoaudiosink', 'sink')
+        self.gst_pipeline.add(self.gst_sink)
+
+        # The audio URI chain
+        gst.element_link_many(self.gst_uri_src, self.gst_volume, self.gst_sink)
+
+        # The audio data chain
+        gst.element_link_many(self.gst_data_src, self.gst_volume,
+            self.gst_sink)
+
+    def _run(self):
+        while True:
+            # TODO Handle commands
+            self.gobject_context.iteration(True)
+
+    def process_message(self, bus, message):
+        if message.type == gst.MESSAGE_EOS:
+            pass # TODO Handle end of track/stream
+        elif message.type == gst.MESSAGE_ERROR:
+            self.gst_bin.set_state(gst.STATE_NULL)
+            error, debug = message.parse_error()
+            logger.error(u'%s %s', error, debug)
+
+    def deliver_data(self, caps_string, data):
+        """Deliver audio data to be played"""
+        caps = gst.caps_from_string(caps_string)
+        buffer_ = gst.Buffer(data)
+        buffer_.set_caps(caps)
+        self.gst_data_src.emit('push-buffer', buffer_)
+
+    def play_uri(self, uri):
+        """Play audio at URI"""
+        self.gst_uri_src.set_state(gst.STATE_READY)
+        self.gst_uri_src.set_property('uri', uri)
+        self.gst_uri_src.set_state(gst.STATE_PLAYING)
+        # TODO Return status
+
+    def state_playing(self):
+        """
+        Set the state to PLAYING.
+
+        Previous state should be READY or PAUSED.
+        """
+        result = self.gst_uri_src.set_state(gst.STATE_PLAYING)
+        return result == gst.STATE_CHANGE_SUCCESS
+
+    def state_paused(self):
+        """
+        Set the state to PAUSED.
+
+        Previous state should be PLAYING.
+        """
+        result = self.gst_uri_src.set_state(gst.STATE_PAUSED)
+        return result == gst.STATE_CHANGE_SUCCESS
+
+    def state_ready(self):
+        """
+        Set the state to READY.
+        """
+        result = self.gst_uri_src.set_state(gst.STATE_READY)
+        return result == gst.STATE_CHANGE_SUCCESS
+
+    def get_volume(self):
+        """Get volume in range [0..100]"""
+        gst_volume = self.gst_volume.get_property('volume')
+        return int(gst_volume * 100)
+
+    def set_volume(self, volume):
+        """Set volume in range [0..100]"""
+        gst_volume = volume / 100.0
+        self.gst_volume.set_property('volume', gst_volume)