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Rules of the
AudioLocker
The rules for creating and operating
the AudioLocker were important to our understanding
of what direction we were to undertake. The following
is the outline of the rules we’ve created.
1. Operations
A. The system plays groups of audio
files during certain times of day. The files within
a group are played in sequence until that group’s
"end time" is reached or exceeded.
B. The audio files are of any length
because they are cut-down versions of NPR programs.
The files can be uncompressed .WAV, .AIFF, .MP2
and other files supported by the Microsoft ActiveMovie
Control, version 2.0.
C. AudioLocker does not "fill
time" to pad a file’s length to an hour
or half-hour, but rather, AudioLocker continues
to play the files within a group, in sequence, until
that group’s end time is reached or exceeded.
D. A group will not start playing
any sooner than its "start time" and no
later than the longest audio file in the previous
group – minus one second. For example, if a
group’s end time is 13:59:59 and a file within
that group ends at 13:59:59, another file within
that group will play. After that file finishes,
a new group will be loaded and the first available
file in the new group will play.
E. AudioLocker is day-sensitive and
supports overnight services whenever a group is
programmed to play past midnight.
F. All activity is printed to a log.
G. A manual control panel is available
by menu and gives the user the power to force the
next event to interrupt the current file immediately
and to "insert" a file of the user’s
choosing as a "one-time" event. The inserted
file, if available, will play after the current
file ends, and only will play once. The AudioLocker
playlist resumes after the inserted file finishes.
H. AudioLocker is fault-tolerant of
missing or unavailable audio files, and simply skips
over the unavailable file. This file will be played,
if it becomes available, after the other valid files
in the group have been played.
I. If a group has no valid
files at all, a file called emergency.wav will play
until that group’s end time is reached or exceeded.
J. If a gap in the schedule exists
where no files were schedule to play, AudioLocker
will continue to play the previous group. If AudioLocker
was started during this schedule gap, the emergency.wav
file will play until a group is found which has
a start time equal to or earlier than the present
time of day.
K. Schedules can be written with any plain-text word
processor, and loaded into AudioLocker’s database
in one of the following ways
1. Before AudioLocker starts by
using the "load" command line parameter.
2. After the current file finishes
playing.
3. After the current group’s
End Time is reached or exceeded.
4. Or, the user may cancel the file
load, and restore the previous schedule.
L. A copy of the database can be saved
as a plain-text file – menu: File | Save Schedule
As –, which is suitable for editing and/or
reloading at a later date.
M. The plain-text schedule may include
comments prefaced with a single apostrophe (‘)
as the first character on the line
N. The minimum number of files in
any group: one. Maximum number: currently limited
to 1,024.
2. Limitations
A. 1,024 lines of schedule can be
displayed and setting MAX_ARRAY to the desired number,
and recompiling the program can overcome this limitation.
B. There is no practical limitation
to the number of lines in the database.
C. As of version 1.16, there is no
provision for repairing the database or compacting
the database from within AudioLocker.
D. Schedules are not checked for correct
timings, group overlaps, or other problems, only
for correct syntax.
E. AudioLocker does not check the
predicted "next event" time with the time-of-day
when a file stops; it simply plays the next event
as calculated when the original file started playing.
If a file is stopped or paused for any appreciable
amount of time, then allowed to finish, the next
event file will be played, regardless of the group’s
end time being reached or exceeded.
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