skip distributing the lsp file as such

[rrq/newlisp/alsa-dispatcher.git] / alsa-dispatcher.8.adoc

diff --git a/alsa-dispatcher.8.adoc b/alsa-dispatcher.8.adoc
index 64e8227d39722bc68edfd7c635a91e0239369f66..0ea690b70c1bd08c53a6b444dd6c4b5a3dad5e95 100644 (file)
--- a/alsa-dispatcher.8.adoc
+++ b/alsa-dispatcher.8.adoc
@@ -4,87 +4,113 @@
 
 == NAME
 
 
 == NAME
 

-alsa-dispatcher - ALSA playback priority dispatcher for temporarily
-connected playback endpoints.
+alsa-dispatcher - ALSA priority dispatcher for occasional playback
+endpoints.

 
 == SYNOPSIS
 
 
 == SYNOPSIS
 

-*alsa-dispatcher.lsp*
+*alsa-dispatcher*

 
 == DESCRIPTION
 
 
 == DESCRIPTION
 

-*alsa-dispatcher.lsp* is an ALSA utility that handles dispatch of
-audio playback via a priority list of possible endpoints. The dispatch
-logic works through the list trying to open each ALSA PCM device in
-order until one succeeds, and thereafter *alsa-dispatcher.lsp* simply
+*alsa-dispatcher* is an ALSA utility that handles dispatch of audio
+playback via a priority list of possible endpoints. The dispatch logic
+works through the list trying to open each ALSA PCM device in order
+until one succeeds, and thereafter *alsa-dispatcher* simply

 channels the playback audio stream from its standard input to the
 successfully opened PCM playback device.
 
 channels the playback audio stream from its standard input to the
 successfully opened PCM playback device.
 

-The program is a _newlisp_ script of manageable size which links up
-with _libasound.so_ for ALSA API actions.
-
-== CONFIGURATIONS
-
-The setup for using *alsa-dispatcher.lsp* includes two configuration
+The setup for using *alsa-dispatcher* includes two configuration

 aspects:
 
 aspects:
 

- 1. The ALSA configuration collection needs to be augmented with a
- _pcm_ block that directs playback to *alsa-dispatcher.lsp* and
- capture from, say, _plughw_ (i.e., the primary sound card).
+ 1. The ALSA configuration needs to be augmented with a _pcm_ block
+ that directs playback to *alsa-dispatcher* and capture from, say,
+ _plughw_ (i.e., the primary sound card).

 
 

- 2. The priority list of posible endpoints for *alsa-dispatcher.lsp*
+ 2. The priority list of possible endpoints for *alsa-dispatcher*

  is a text file named _$HOME/.alsa-dispatcher_.
 
  is a text file named _$HOME/.alsa-dispatcher_.
 

-[]
-
-*ALSA configuration (e.g. $HOME/.asoundrc)*::
+=== ALSA configuration (e.g. $HOME/.asoundrc)

 
 The ALSA configuration collection needs to include a declaration for
 *alsa-dispatcher* as an ALSA PCM by means of a short declaration in
 
 The ALSA configuration collection needs to include a declaration for
 *alsa-dispatcher* as an ALSA PCM by means of a short declaration in

-the user's _$HOME/.asoundrc_ file or system-wide in
-_/etc/asoundrc.conf_ The following is an example _$HOME/.asoundrc_.
-+
+the user's _$HOME/.asoundrc_ file or system-wide (e.g
+_/etc/asoundrc.conf_ or _/etc/alsa/conf.d/51-alsa-dispatcher.conf_)
+
+The following is an example _$HOME/.asoundrc_.
+

 ----
 pcm.!default dispatch
 
 pcm.dispatch {
     type asym
     playback {
 ----
 pcm.!default dispatch
 
 pcm.dispatch {
     type asym
     playback {

-        pcm "file:|exec /usr/local/bin/alsa-dispatcher.lsp"
+        pcm {
+           type plug
+           slave {
+               pcm "file:|exec /usr/bin/alsa-dispatcher"
+               format S16_LE; channels 2; rate 48000;
+           }
+       }

     }
     capture plughw
 }
 ----
     }
     capture plughw
 }
 ----

-+
+

 The first line in the example asserts that "dispatch" is the default
 The first line in the example asserts that "dispatch" is the default

-PCM.
-+
-The lines below that declares the "dispatch" PCM to have its playback
-stream directed to the command _/usr/local/bin/alsa-dispatcher.lsp_
-via a pipe (that is where *alsa-dispatcher.lsp* is for this example),
+PCM. I.e. that playback directed to "default" should be passed on to
+"dispatch".
+
+The lines below declares the "dispatch" PCM to have its playback
+stream directed to the command _/usr/local/bin/alsa-dispatcher_
+via a pipe (that is where *alsa-dispatcher* is for this example),

 and the "dispatch" PCM capture stream is sourced from _plughw_ (i.e.
 the default sound card).
 
 and the "dispatch" PCM capture stream is sourced from _plughw_ (i.e.
 the default sound card).
 

-*About $HOME/.alsa-dispatcher*::
+Note that the playback PCM explicitly declares the stream
+characteristica (format, channels and rate) used up by
+*alsa-dispatcher*.
+
+=== About $HOME/.alsa-dispatcher
+
+The endpoints are enumerated for *alsa-dispatcher* in a text file
+_$HOME/.alsa-dispatcher_ with one line for each PCM device. The line
+contains PCM name and optionally setting variations for that device,
+in the form of _key=value_. Currently only _latency_ may be varied.
+
+Blank lines and lines starting with "#" are comments. The following is
+an illustration example.

 
 

-Possible endpoints are enumerated for *alsa-dispatcher.lsp* in a text
-file _$HOME/.alsa-dispatcher_ with one line for each PCM device. The
-line contains its name and optionally some specific setting variation
-for that device. Such settings have the form of _key=value_ with space
-seapartion between settings. Blank lines and lines starting with "#"
-are comments. The following is an illustration example.
-+

 ----
 bt
 ----
 bt

+usb

 plughw
 ----
 plughw
 ----

-+
+

 The example _$HOME/.alsa-dispatcher_ nominates _bt_ as the first ALSA
 The example _$HOME/.alsa-dispatcher_ nominates _bt_ as the first ALSA

-PCM to try, and _plughw_ as the second (and last). This illustrates
-ain imagined setup with a bluetooth device _bt_ that should have
-priority when in use. *alsa-dispatcher.lsp* will direct playback to
-_bt_ if it is in use and otherwise fall back on _plughw_ (i.e. the
-default sound card).
+PCM to try, then the _usb_ device and the _plughw_ as the third and
+last option. It's an imagined setup with a bluetooth device _bt_ that
+should have priority when in use, next a USB sound card _usb_ as
+secondary option when in use, and thirdly the default sound card
+_plughw_.
+
+Thus, *alsa-dispatcher* will try to direct playback to _bt_ first. If
+that is not in use *alsa-dispatcher* tries to direct playback to _usb_
+and if the is not in use either, then *alsa-dispatcher* directs
+playback to _plughw_ (i.e. the default sound card).
+
+== NOTES
+
+*alsa-dispatcher* keeps playback channeling to a selected endpoint as
+long as that is available. If the endpoint goes away, or the
+*alsa-dispatcher* program is killed, that channeling is interrupted.
+Then the original sound source (eg a browser) may establish a new
+playback sink, which would caue a new *alsa-dispatcher* to run through
+the priority list again to pick the first option available in the then
+current audio context.
+
+The program is an embedded _newlisp_ script of manageable size that
+links up with _libasound.so_ for ALSA API actions.

 
 == SEE ALSO
 
 
 == SEE ALSO