| The sound
used with both filmstrip projection systems varies
in its technical specifications from system to system.
Maximum and minimum program lengths, cue signal
frequencies and spacing and cue levels are different
for each projection system. The actual requirements
for any system are best determined by consultation
with the system manufacturer or the laboratory.
In general, the producer
is requested to supply the original sound on a
¼" 7 ½" ips dual track
magnetic tape. The audio portion of the program
should be on the A channel (left track), and the
cue signals on the B channel (right track). Note
that this is dual track tape, and not the 4-track
stereo used in home music systems.
If the producer wants the laboratory
to add the cue signals, the producer must supply
a clearly marked script that is an exact transcription
of the audio track. topˆ
Synchronization
Since the picture and sound in a filmstrip or
sound-slide projection system are on two separate
mediums, special precautions must be taken to
insure that the picture and sound portion of the
program are brought into synchronization when
the program begins. The most common method of
assuring this synchronization is to make the first
picture on the filmstrip or the first slide in
the set, a frame that clearly says "Start
Sound Here". This frame is usually also a
focus frame. The user of the program advances
only the picture portion until the "Start
Sound Here" frame appears, and then actuates
the audio or system start. If leader frames are
needed in a filmstrip program before the "Start
Sound Here" frame, they can be black frames,
or frames which say "Advance To Focus."
In sound filmstrip systems that
use pictures and sound spliced into continuous
loops, the producer must be careful to cue his
audio to advance the picture loop through the
frames between the last picture frame of the program
and the "Start Sound Here" frame before
the audio stops.
Four frames are usually used
between the last picture frame of the program
and the "Start Sound Here" frame to
splice the picture loop together. This number
should be confirmed with the laboratory before
cueing the audio. If the lab does in fact use
four frames, then five additional advance cues
followed by a stop cue would be placed on the
tape following the audio for the last picture
frame. See Figure 20 - Cueing of Continuous Loops
to Return to Start. This results in the program
stopping with the "Start Sound Here"
frame on the screen, and the audiotape in position
for the start of the program. topˆ |
