== SYNOPSIS
-*alsa-dispatcher.lsp*
+*alsa-dispatcher*
== 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.
-The program is a _newlisp_ script of manageable size which links up
-with _libasound.so_ for ALSA API actions.
-
-The setup for using *alsa-dispatcher.lsp* includes two configuration
+The setup for using *alsa-dispatcher* includes two configuration
aspects:
1. The ALSA configuration needs to be augmented with a _pcm_ block
- that directs playback to *alsa-dispatcher.lsp* and capture from, say,
+ that directs playback to *alsa-dispatcher* and capture from, say,
_plughw_ (i.e., the primary sound card).
- 2. The priority list of possible endpoints for *alsa-dispatcher.lsp*
+ 2. The priority list of possible endpoints for *alsa-dispatcher*
is a text file named _$HOME/.alsa-dispatcher_.
=== ALSA configuration (e.g. $HOME/.asoundrc)
The ALSA configuration collection needs to include a declaration for
*alsa-dispatcher* as an ALSA PCM by means of a short declaration in
-the user's _$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 {
type plug
slave {
- pcm "file:|exec /usr/bin/alsa-dispatcher.lsp"
+ pcm "file:|exec /usr/bin/alsa-dispatcher"
format S16_LE; channels 2; rate 48000;
}
}
PCM. I.e. that playback directed to "default" should be passed on to
"dispatch".
-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),
-and the "dispatch" PCM capture stream is sourced from _plughw_ (i.e.
-the default sound card).
+The rest of the example declares the "dispatch" PCM to be an "asym"
+that has the playback stream directed via a pipe to the command
+_/usr/bin/alsa-dispatcher_ (which is where *alsa-dispatcher* is
+installed in this example), and further it has the capture stream
+sourced from _plughw_ (i.e. the default sound card).
Note that the playback PCM explicitly declares the stream
-characteristica (format, channels and rate) used up by
-*alsa-dispatcher.lsp*.
+characteristics (format, channels and rate) as used by
+*alsa-dispatcher*.
=== About $HOME/.alsa-dispatcher
-The endpoints are enumerated for *alsa-dispatcher.lsp* in a text file
+The endpoints are enumerated for *alsa-dispatcher* in a text file
_$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.
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
+secondary option when in use, and third the default sound card
_plughw_.
-Thus, *alsa-dispatcher.lsp* will try to direct playback to _bt_ first.
-If that is not in use *alsa-dispatcher.lsp* tries to direct playback
-to _usb_ and if the is not in use either, then *alsa-dispatcher.lsp*
-directs playback to _plughw_ (i.e. the default sound card).
+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.lsp* keeps playback channeling to a selected endpoint
-as long as that is available. If the endpoint goes away, or the
-*alsa-dispatcher.lsp* 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.lsp* to run through the priority list again to pick
-the first option available in the then current audio context.
+*alsa-dispatcher* keeps channeling playback to a selected endpoint as
+long as that remains available. If the endpoint goes away (or the
+*alsa-dispatcher* program is killed) that channeling is interrupted.
+The original sound source (eg a browser) may then establish a new
+playback sink, which would cause 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
projects / rrq / newlisp / alsa-dispatcher.git / blobdiff