Quick Reference
GrainMill Reference
BrkEdit Reference
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Glossary Items
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The infile
The infile is the currently selected soundfile to be processed. It must
be a mono soundfile (one channel), 16-bit (in the current version), and
either
WAV or AIF format. As with any sound processing, the qualities of the
infile greatly influence the result.
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The outfile
The outfile is produced by GrainMill. It will be mono
or stereo depending on the options selected. The program automatically
provides a name
for the outfile by adding 'OUT' to the name of the infile. For
example, if your infile was called 'piano.wav', the default outfile name
would be
'pianoOUT.wav'. You could name a second version, 'pianoOUT1.wav', etc.
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What is a 'grain' of sound?
A 'grain' is a tiny bit of something - in this case sound rather than e.g.,
sand or corn. A sound made up of lots of small 'grains' usually has a somewhat
uneven texture. It can sound just a bit rough-textured or bumpy, or may
sound fiercely repetitive. Similarly to the paintings of Seurat,
who used tiny dots of paint rather than the usual brush stroke, the sound
is made up of lots and lots of tiny pieces. A sound made up of grains is
described as 'granular', and creating sounds like this is called 'granular
synthesis'.'
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Decibels: a measure of loudness
The scale of loudness calculated in decibels (abbreviated as dB) is a logarithmic
scale. The logarithmic scale is used for decibels because this is how the
ear works. What this means is simply that equal divisions of the scale
will sound to us as equally louder or softer, whereas mathematically the
values are actually doubling. Logarithms are a way of linking linear and
geometric values (such as 1, 2, 3,4 and 2,4, 8, 16): a single (i.e., equally
spaced) step in the linear scale involves a doubling of the previous value
in the geometric scale. If the loudness scale were to be represented on
the screen as a linear scale (and the same is true of pitch), most of the
changes that we can perceive with our ears would be bunched together at
one end of the scale. Textbooks on acoustics provide a full mathematical
explanation of these matters, and often include a chart illustrating where
familiar sounds normally come on the scale of decibels.
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Milliseconds: a measure of time
A millisecond (abbreviated as ms) is one thousandth part of a second. The
thousandth decimal place is the third to the right of the decimal point
(tens-hundreds-thousands). So 1 millisecond can also be written as 0.001
sec, 50 ms can be written as 0.050 sec, and 100 ms is the same as 0.1 sec.
To convert from milliseconds to seconds, move the decimal point three places
to the left (adding zeroes if necessary), and to convert from seconds to
milliseconds, move the decimal point three places to the right.
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Timbre: a description of tone quality
Timbre means the 'colour' of a sound, which in turn is described technically
by its 'spectrum' - how many and which frequencies are present as
the sound flows
through time. This frequency content is constantly changing, in some
sounds more than in others. For example, a flute has a clear luminous tone,
while an oboe has a considerably more complex sound, and a locomotive
engine has a very rich sound indeed! 'Colour' is but one of the many
words borrowed from the visual arts to describe sonic differences;
they all come down to the ever-changing frequency content of a sound.
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Splices: Butt and sloping joins
In the 'classical tape studio', analog tape was spliced by cutting off
selected pieces with a razor blade and then joining up the pieces with
a special white splicing tape. These cuts were usually made with the help
of a splicing block, and there was a groove at 45% for a 'smooth' join
(the two pieces of tape would overlap) and a vertical groove for what was
called a butt edit (no overlap at all). Similarly, in GrainMill,
the grains are 'abutted' when there is no overlap. However, note that there
is in this case still the tapering of the sound from and to zero volume,
with which each grain is shaped in order to avoid clicks.
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Panning a sound
The terminology 'to pan a sound', 'panning a sound', or just 'panning',
refers to the psycho-acoustic effect whereby sound appears to move through
space. To illustrate: a (stereo) sound can 'move' from left to right. In
this case, the stereo image is actually coming out of both speakers, but
the right hand speaker starts with zero volume and the left hand speaker
with full volume. Then the right hand speaker gets progressively louder
as the left hand speaker gets progressively quieter. To the ear of the
listener (positioned centrally in front of both speakers), the sound appears
to move from left to right.
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Mono Soundfile
'Mono' is short for 'monophonic' - literally, 'one sound'. A mono
soundfile has only 1 'channel'. If there are two loudspeakers, the (same)
sound
signal is output by both of them.
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Defaults
Programs frequently use 'defaults'. A default is a pre-set 'typical' or
'recommended' value, or simply a parameter setting to get started with.
The
defaults in GrainMill allow you to start the program, load a
soundfile, click on MAKE IT and get something interesting!
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Attack - Sustain - Decay
These terms refer to the loudness shape (amplitude 'envelope') of the sound.
They describe some of the most noticeable and important features of a sound.
The attack describes how the sound begins, in particular how quickly the
loudness increases; the Sustain portion refers to the loudness characteristics
of the main part of the sound the Decay portion is how it ends, for example
whether it stops abruptly or gradually trails off into silence. Each grain
created by GrainMill has a simple, symmetrical, ASD shape. Note
that the more familiar acronym ADSR, standing for Attack-Decay-Sustain-Release,
while acknowledging that the attack of many sounds reaches a peak point
from which it falls back (decays) to the Sustain level (e.g. many
brass sounds), is named specifically for keyboards - the Release
refers literally to the release of a key, triggering the final Decay of
the sound.
Experimenting with BrkEdit is one of the best ways of exploring
amplitude envelopes.
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