alsa: document alsa mixer path/profile sets a bit more

2 files changed, 23 insertions, 3 deletions

diff --git a/src/modules/alsa/mixer/paths/analog-output.conf.common b/src/modules/alsa/mixer/paths/analog-output.conf.common
index 47243dbc..cc1185f4 100644
--- a/src/modules/alsa/mixer/paths/analog-output.conf.common
+++ b/src/modules/alsa/mixer/paths/analog-output.conf.common
@@ -48,6 +48,10 @@
 ; combined and made into a "port". So make sure you don't list too
 ; many switches/enums for exposing, because the number of ports might
 ; rise exponentially.
+;
+; Only one path can be selected at a time. All paths that are valid
+; for an audio device will be exposed as "port" for the sink/source.
+
 
 ; [General]
 ; priority = ...                         # Priority for this path
@@ -84,6 +88,10 @@
 ;
 ; override-map.1 = ...                   # Override the channel mask of the mixer control if the control only exposes a single channel
 ; override-map.2 = ...                   # Override the channel masks of the mixer control if the control only exposes two channels
+;                                        # Override maps should list for each element channel which high-level channels it controls via a
+;                                        # channel mask. A channel mask may either be the name of a single channel, or the words "all-left",
+;                                        # "all-right", "all-center", "all-front", "all-rear", and "all" to encode a specific subset of
+;                                        # channels in a mask
 
 [Element PCM]
 switch = mute
diff --git a/src/modules/alsa/mixer/profile-sets/default.conf b/src/modules/alsa/mixer/profile-sets/default.conf
index 6ae11b47..ac41a8d3 100644
--- a/src/modules/alsa/mixer/profile-sets/default.conf
+++ b/src/modules/alsa/mixer/profile-sets/default.conf
@@ -16,8 +16,18 @@
 
 ; Default profile definitions for the ALSA backend of PulseAudio. This
 ; is used as fallback for all cards that have no special mapping
-; assigned. (and should be good enough for the vast majority of cards)
-;
+; assigned. (and should be good enough for the vast majority of
+; cards).  Use the udev property PULSE_PROFILE_SET to assign a
+; different profile set than this one to a device.  So what is this
+; about? Simply, what we do here is map ALSA devices to how they are
+; exposed in PA. We say which ALSA device string to use to open a
+; device, which channel mapping to use then, and which mixer path to
+; use. This is encoded in a 'mapping'. Multiple of these mappings can
+; be bound together in a 'profile' which is then directly exposed in
+; the UI as a card profile. Each mapping assigned to a profile will
+; result in one sink/source to be created if the profile is selected
+; for the card.
+
 ; [General]
 ; auto-profiles = no | yes                  # Instead of defining all profiles manually, autogenerate
 ;                                           # them by combining every input mapping with every output mapping.
@@ -42,7 +52,9 @@
 ;                                           # defined in this file too
 ; description = ...
 ; priority = ...                            # Numeric value to deduce priority for this profile
-; skip-probe = no | yes                     # Skip probing for availability?
+; skip-probe = no | yes                     # Skip probing for availability? If this is yes then this profile
+;                                           # will be assumed as working without probing. Makes initialization
+;                                           # a bit faster but only works if the card is really known well.
 
 [General]
 auto-profiles = yes