bathroomd: Turn your Squeezebox off while the light is out

Version 0.1                                                      16.09.2011

(c) 2011 Enno Luebbers <luebbers_at_reconos.de>


DISCLAIMER
----------

I don't provide any guarantees that the script works as intended and doesn't
cause any damage to your Squeezebox. Use at your own risk.

bathroomd has been tested with a Logitech Squeezebox Radio, firmware version
7.6.1 r9482. Your mileage may vary with other devices and versions.


SYNOPSIS
--------

The most annoying thing about putting your Squeezebox into your bathroom is
the fact that you need to manually turn it on or off. Wouldn't it be awesome 
if your Squeezebox turned itself on when you switch on the light in the
bathroom, and turn off when your leave and switch off the light?

Enter bathroomd, a hugely sophisticated quick hack which reads out your
Squeezebox's ambient light sensor and mutes the playback volume when the
ambient brightness falls below a certain threshold, as well as turning the
volume back up when the brightness rises above a (second) threshold.


INSTALLATION
------------

1. Copy the bathroomd script onto your Squeezebox using SSH, preferably into
   the /usr/bin directory. You might need to enable SSH access first in your
   Squeezebox's settings.
   
2. Add the following line to the end of  your Squeezebox's /etc/init.d/rcS
   script:
   
        /usr/bin/bathroomd &
        
3. Edit the /usr/bin/bathroomd script to suit your needs. Especially the
   constants THRESHOLD_HI and THRESHOLD_LO might need tweaking to account
   for the particular brightness levels in your bathroom. You can run
   bathroomd manually with the '-v' switch to see the data read from the
   ambient light sensor.
   
   
DEINSTALLATION
--------------

Just remove /usr/bin/bathroomd and the line added to /etc/init.d/rcS in step
2 above. You can alternatively restore your Squeezebox to its factory 
settings by holding the 'ADD' button when powering it on.


KNOWN ISSUES
------------

bathroomd only mutes the PCM volume. This has the nice effect that it
remembers the volume you set using the volume knob; it might however not
work with line in or other audio sources.

Because bathroomd only mutes the volume, playback continues even when you are
not in the bathroom. This is neither energy efficient nor elegant; if anyone
knows of a way to start/stop playback from the Squeezebox's command line, 
please contact me.

bathroomd doesn't do any error checking. It's just a hack.

bathroomd periodically checks the ambient light sensor; this activity might
be (in fact, it is) noticeable and cause some jitter in the interface. I
haven't experienced any degradation in sound quality, though. You might want
to increase the CHECK_INTERVAL (in seconds) if the lag bothers you.

If you have a real window in your bathroom, this won't work.