audio: Change to software mixing by default

docs/changelog.rst

@@ -45,6 +45,13 @@ Still in development.
   the library's :meth:`~mopidy.core.LibraryController.find_exact` and
   :meth:`~mopidy.core.LibraryController.search` methods.
 
+**Audio**
+
+- Change default volume mixer from ``autoaudiomixer`` to ``software``.
+  GStreamer 1.x does not support volume control, so we're changing to use
+  software mixing by default, as that may be the only thing we'll support in
+  the future when we upgrade to GStreamer 1.x.
+
 **Local backend**
 
 - Library scanning has been switched back to custom code due to various issues

docs/config.rst

@@ -60,17 +60,23 @@ Core configuration values
 
     Audio mixer to use.
 
-    Expects a GStreamer mixer to use, typical values are: ``autoaudiomixer``,
-    ``alsamixer``, ``pulsemixer``, ``ossmixer``, and ``oss4mixer``.
+    Expects a GStreamer mixer to use, typical values are: ``software``,
+    ``autoaudiomixer``, ``alsamixer``, ``pulsemixer``, ``ossmixer``, and
+    ``oss4mixer``.
 
-    The default is ``autoaudiomixer``, which attempts to select a sane mixer
-    for you automatically. When Mopidy is started, it will log what mixer
-    ``autoaudiomixer`` selected, for example::
+    The default is ``software``, which does volume control inside Mopidy before
+    the audio is sent to the audio output. This mixer does not affect the
+    volume of any other audio playback on the system. It is the only mixer that
+    will affect the audio volume if you're streaming the audio from Mopidy
+    through Shoutcast.
+
+    If you want to use a hardware mixer, try ``autoaudiomixer``. It attempts to
+    select a sane hardware mixer for you automatically. When Mopidy is started,
+    it will log what mixer ``autoaudiomixer`` selected, for example::
 
         INFO     Audio mixer set to "alsamixer" using track "Master"
 
-    Setting the config value to blank turns off volume control. ``software``
-    can be used to force software mixing in the application.
+    Setting the config value to blank turns off volume control.
 
 .. confval:: audio/mixer_track
 

mopidy/audio/mixers/auto.py

@@ -1,9 +1,7 @@
 """Mixer element that automatically selects the real mixer to use.
 
-This is Mopidy's default mixer.
-
-If this wasn't the default, you would set the :confval:`audio/mixer` config
-value to ``autoaudiomixer`` to use this mixer.
+Set the :confval:`audio/mixer` config value to ``autoaudiomixer`` to use this
+mixer.
 """
 
 from __future__ import unicode_literals

mopidy/config/default.conf

@@ -8,7 +8,7 @@ config_file =
 pykka = info
 
 [audio]
-mixer = autoaudiomixer
+mixer = software
 mixer_track =
 output = autoaudiosink
 visualizer =