91 lines
2.4 KiB
Python
91 lines
2.4 KiB
Python
"""Mixer element that automatically selects the real mixer to use.
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This is Mopidy's default mixer.
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Dependencies
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============
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None
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Configuration
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=============
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If this wasn't the default, you would set the :confval:`audio/mixer` config
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value to ``autoaudiomixer`` to use this mixer.
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"""
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from __future__ import unicode_literals
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import pygst
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pygst.require('0.10')
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import gst
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import logging
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logger = logging.getLogger('mopidy.audio.mixers.auto')
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# TODO: we might want to add some ranking to the mixers we know about?
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class AutoAudioMixer(gst.Bin):
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__gstdetails__ = (
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'AutoAudioMixer',
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'Mixer',
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'Element automatically selects a mixer.',
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'Mopidy')
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def __init__(self):
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gst.Bin.__init__(self)
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mixer = self._find_mixer()
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if mixer:
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# pylint: disable=E1101
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self.add(mixer)
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# pylint: enable=E1101
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logger.debug('AutoAudioMixer chose: %s', mixer.get_name())
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else:
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logger.debug('AutoAudioMixer did not find any usable mixers')
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def _find_mixer(self):
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registry = gst.registry_get_default()
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factories = registry.get_feature_list(gst.TYPE_ELEMENT_FACTORY)
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factories.sort(key=lambda f: (-f.get_rank(), f.get_name()))
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for factory in factories:
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# Avoid sink/srcs that implement mixing.
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if factory.get_klass() != 'Generic/Audio':
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continue
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# Avoid anything that doesn't implement mixing.
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elif not factory.has_interface('GstMixer'):
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continue
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if self._test_mixer(factory):
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return factory.create()
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return None
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def _test_mixer(self, factory):
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element = factory.create()
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if not element:
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return False
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try:
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result = element.set_state(gst.STATE_READY)
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if result != gst.STATE_CHANGE_SUCCESS:
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return False
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# Trust that the default device is sane and just check tracks.
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return self._test_tracks(element)
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finally:
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element.set_state(gst.STATE_NULL)
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def _test_tracks(self, element):
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# Only allow elements that have a least one output track.
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flags = gst.interfaces.MIXER_TRACK_OUTPUT
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for track in element.list_tracks():
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if track.flags & flags:
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return True
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return False
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