This hack adds a volume daemon webservice for moodeaudio and modifies moode to make use of it.
The volume daemon allows much more responsive control of volume from the moode web interface. This transforms drag and drop control of volume from being barely usable on a pi-based moode player into a fast, responsive and pleasant experience. It also provides timely feedback when volume or mute is changed by other actors.
The volume knob display has been split into into two parts. The selector knob, itself which now appears as a notch, and the rotary slider volume display. When changing the volume through the UI, the notch moves in real time with no lag whatsoever. The slider catches up as the selected changes are made on the player.
If volume is changed by some other cause (eg another user on a separate UI), the rotary slider quickly shows the change, and the notch will catch-up a little later. Whenever the notch and the rotary slider are out of step, the numeric volume display will be shown in green. When they are in step, the numeric display changes to white (the same colour as the playback time indicator).
Volume curve correction is not currently implemented. See Future Directions below.
Volumed is now responsible for directly controlling mpd and/or amixer.
It accepts volume changing commands and asynchronously applies them to
the hardware. When the volume, or mute status, changes it sends
notifications back through the websocket. It is also responsible
(currently - see Future Directions below) for updating the sqlite3
database to record such changes.
Volumed also implements muting through the amixer mute mechanism if hardware volume control is being used.
The javascript client interface has been changed to make use of volumed. This means it no longer has to deal with database updates or directly manipulate amixer or mpd. If it cannot maintain contact with the volume daemon it falls back to its old behaviour (though with the notched volume control).
volumed.py and volumec.py are implemented in python. The following
extra packages are required:
-
python-geventInstalled usingapt-get install python-gevent -
ws4py' Not available as a debian package so installed from git. The version I used was from commit641d3c6d073d9c7ebd738c68359417c7b088d6a5`.Copy the ws4py directory into:
/usr/local/lib/python2.7/site-packages
volumed.py and volumec.py are currently located in /var/www. This
will be corrected when (if) volumed is properly packaged.
The service files for systemd are volumed.service and
volumec.service. Copy these files to /lib/systemd/system/ and then
run:
# systemctl enable volumed.service
# systemctl enable volumec.service
Commands are sent to volumed and the current status is returned.
Commands may internally be aggregated (eg vol +1, vol +1, vol +1,
may be aggregated into a single vol +3 which is sent to the hardware).
In such a case, only the last command will result in a response. Also
responses will be sent whenever volumed detects that the volume or mute
status has changed.
This means that although sending a command will usually result in a single response, this is not guaranteed. Volumed is intended for asynchronous use.
The commands accepted by volumed are:
-
volA volume query, which will illicit a response, though multiple queries may be aggregated resulting in only a single response. -
vol +nIncrease volume by n percentage units. A response is illicited. Volume is limited to the max percentage set in the database. -
vol -nIncrease volume by n units. A response is illicited. Volume cannot decrease below zero. -
vol nSet volume to n%. A response is illicited.
All reponses are in the form:
Vol: 99, Mute: off
The volume value is a percentage from 0 to 100. The values of mute are "off" and "on".
In addition to the volumed daemon, there is another executable,
volumec.py This is a volumed client, allowing a command-line user
interface to volumed. It can be used as a one-shot command,
interactively through stdin, through a named-pipe, or as a daemon lirc
client. This allows infra-red remote controls to be easily set up with
good responsiveness.
Single-shot (command) usage:
$ volumec.py -c "command"
(where command will be vol, vol +N, etc)
Interactive usage:
$ volumec.py
commands may be typed interactively, responses will be shown when they are received.
Through a named-pipe (fifo)
$ mkfifo my-named-pipe$ volumec.py -f my-named-pipe -o
And then to send a command, simply echo it to the named pipe:
$ echo "vol +3" my-named-pipe
As an lirc client (called volumec):
$ volumec.py -d -q
In this mode button presses from an infra-red control will be passed to volumec, which will in turn pass them on to volumed. This is much faster and more responsive than using irexec to execute shell commands.
Example lines from an lircrc file follow:
begin
button = KEY_VOLUMEDOWN
repeat = 1
prog = volumec
config = vol -1
end
begin
button = KEY_VOLUMEUP
repeat = 1
prog = volumec
config = vol +1
end
begin
button = KEY_MUTE
prog = volumec
config = mute
config = unmute
end
The volumed daemon should not access the moode database. This limits its usefulness to moode audio, though the general mechanism should work well for volumio, runeaudio and others.
The proper way to do this would be to use a configuration file to configure max_pct, hardware volume control, etc, and to create a websocket client to manage database access. Different clients could then be built for moode, volumio, runeaudio, etc.
It might also be appropriate to allow configuration to be performed by sending special configuration commands.
Volume curve correction should be added. Note that this needs to be done for both reading and writing the volume.
Ideally both volumed and volumec would be re-implemented using a compiled language, as the current python implementation is far less efficient than is ideal.
Volumed should become a debian package.