services: mpd: Auto-detect mpd-output mixer type by default.

Relates to <https://issues.guix.gnu.org/63082>.

* gnu/services/audio.scm (mpd-output) [mixer-type]: Change default value from
"none" to unspecified.
* doc/guix.texi (Audio Services): Regenerate doc.

1 files changed, 7 insertions, 4 deletions

diff --git a/doc/guix.texi b/doc/guix.texi
index 7df9a6b8a2..67928d290d 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -34417,8 +34417,9 @@ Partitions} for available options.
 @end table
 @end deftp
 
+@c %start of fragment
 @deftp {Data Type} mpd-output
-Data type representing a @command{mpd} audio output.
+Available @code{mpd-output} fields are:
 
 @table @asis
 @item @code{name} (default: @code{"MPD"}) (type: string)
@@ -34445,15 +34446,16 @@ is only useful for output plugins that can receive tags, for example the
 
 @item @code{always-on?} (default: @code{#f}) (type: boolean)
 If set to @code{#t}, then MPD attempts to keep this audio output always
-open.  This may be useful for streaming servers, when you don?t want to
+open.  This may be useful for streaming servers, when you don’t want to
 disconnect all listeners even when playback is accidentally stopped.
 
-@item @code{mixer-type} (default: @code{"none"}) (type: string)
+@item @code{mixer-type} (type: maybe-string)
 This field accepts a string that specifies which mixer should be used
 for this audio output: the @code{hardware} mixer, the @code{software}
 mixer, the @code{null} mixer (allows setting the volume, but with no
 effect; this can be used as a trick to implement an external mixer
-External Mixer) or no mixer (@code{none}).
+External Mixer) or no mixer (@code{none}).  When left unspecified, a
+@code{hardware} mixer is used for devices that support it.
 
 @item @code{replay-gain-handler} (type: maybe-string)
 This field accepts a string that specifies how
@@ -34468,6 +34470,7 @@ appended to the audio output configuration.
 
 @end table
 @end deftp
+@c %end of fragment
 
 The following example shows a configuration of @command{mpd} that
 configures some of its plugins and provides a HTTP audio streaming output.