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Reminder that this is all just rough for now. Also I squeezed it all
into one file to make things easy to try out, no need to put things in
your path or for it to know where you installed it. Later, when it
becomes a proper package, things will be split up and spread around
properly.
Note that everything is subject to change without notice, this being a
very raw project for now.
aataaj.lua is a polyglot script, written in such a way that several
different things can deal with it, including shell and Lua languages.
The very first line is your typical shell script first line, but telling
the system that it's Lua not shell script. Perl and Python do similar
things, and there is likely plenty of those scattered around your system,
other languages to. Lua basically ignores the first line if it starts
with #. The system that runs files checks the beginning of the file to
see how it should run. Binaries have magic numbers, scripts have this #!
thing. So that system only reads that first line, then passes the script
to that command in the first line.
The next bit of palyglotism is the Sys V LSB comment block. This is the
magic that turns it into an init script you can put in /etc/init.d Any
LSB compliant init program will look for a comment block like that near
the beginning of the script. This is why all the scripts in /etc/init.d
have such a thing near the top. In this case the script type comment
block is wrapped inside a Lua comment block. Lua will ignore it, Shell
interpreters will ignore it, but shouldn't even get this far anyway. LSB
compliant init programs will find what they are looking for.
This tells the system to run it in run level S for Start, and before
alsa-utils and espeakup. So should in theory be the first thing to mess
with ALSA other than the kernel.
The next major blob of stuff in aataaj.lua is the Help text, which is a
copy of README.md. Later the --help option will print README.md instead
of having it's own copy.
The definition of APT is something I just copied from my apt-panopticon
project. Should break it out into it's own separate library some day.
Then comes the argument handling. Handles the usual init script
arguments, plus a couple more. Some are just aliases for "start", for
now.
"stop" is very crude and violent, mostly just killall.
A short bit where you can change some options.
The actual audio device scanning.
Basically we scan through /proc/asound/card[0-9]* looking for audio
devices that the kernel has already recognised. Collect a few details
about what we find, stuff it in the Cards table. For playback devices we
feed some of those details into espeak-ng, so it'll speak them through
this found playback device. If this is running during init startup time,
then the computer should speak through all audio output devices one at a
time, and you should hear it through anything with speakers attached.
If this is "start" then it'll write details about what it found into
/var/lib/aataaj/ files. One is a jack-plumbing config file for the later
JACK stage, the other is a fragment of an ALSA / asound config file you
can include in the real ones. This includes some extra stuff that is
experiments to get ALSA and JACK to behave that are commented out.
If this is "JACK" then it'll start up a bunch of JACK software, and hook
everything up in JACK.
First it starts the JACK server, then starts up a patchbay GUI so you can
watch the rest of what happens.
Next up is jack-plumbing, using that config file we created before. This
automates the various connections we are about to make. Note this config
is only used for this setup phase, you can still use your own
jack-plumbing config.
a2jmidid is up next, which is used to automatically connect MIDI devices
into the JACK system. Alas the same thing doesn't happen with audio
devices, which is why I need this script.
Next we use alsa_in / alsa_out and their zita equivalents to create JACK
devices for all those ALSA devices we found. We start with anything
configured in the alias table, then add the ALSA loopback devices.
Finally we loop through what's left. Since jack-plumbing is running with
our generated config, it'll automatically hook everything up to
everything else.
Next we scan for joysticks, and use aseqjoy to convert them into MIDI
input devices. Just coz. B-)
Next we fire up qsynth, so you have something to play that makes noises.
Finally we wait for a bit, then kill the jack-plumbing we started. It's
done it's job, the user can pick their own session management.
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