596 Chapter 20
razor-blade editing. Using this technique, the tape was physically cut with a razor blade
and joined using a special sticky tape. With the high tape speeds employed in
professional recording, accurate editing was possible using this technique and many
fi ne recordings were assembled this way. Any engineer who has been involved with
razor-blade editing will know that it is a satisfying skill to acquire but it is tricky and it
is always fraught with diffi culties. The reason being that a mistimed or misjudged edit
is diffi cult to put right once the fi rst “ incision ” has been made! So much so that a dub
or copy of the original master tapes was sometimes made for editing lest the original
master should be irreparably damaged by a poor edit. Unfortunately, because analogue
recording is never perfect, this meant that editing inevitably meant one tape-generation
of quality loss before the master tape had left the studio for production. The advent of
digital audio has brought about a new vista of possibility in sound editing. Apart from the
obvious advantages of digital storage, that once the audio signal is in robust digital form
it can be copied an infi nite number of times, thus providing an identical tape “ clone ” for
editing purposes, the arrival of the ability to process digital audio on desktop PCs has
revolutionized the way we think about audio editing, providing a fl exibility undreamed of
in the days of analogue mastering machines.
Editing digital audio on a desktop microcomputer has two major advantages.
(1) An edit may be made with sample accuracy, by which is meant, a cut may be
made with a precision of 1/40,000th of a second!
(2) An edit may be made nondestructively, meaning that when the computer is
instructed to join two separate takes together, it doesn’t create a new fi le with
a join at the specifi ed point, but instead records two pointers that instruct on
subsequent playback to vector or jump to another data location and play from
the new fi le at that point.
In other words, it “ lists ” the edits in a new fi le of stored vector instructions. Indeed this
fi le is known as an edit decision list. (Remember that the hard-disk doesn’t have to jump
instantaneously to another location because the computer holds a few seconds of audio
data in a RAM cache memory.) This opens the possibility of almost limitless editing in
order to assemble a “ perfect ” performance. Edits may be rehearsed and auditioned many
times without ever “ molesting ” the original sound fi les.