Game Development Reference
In-Depth Information
Sound waves can be uniquely shaped, allowing them to “piggyback” various sound
effects. A “pure,” or baseline, type of sound wave is called a
sine wave
(which you
learned about in high school trigonometry, with the sine, cosine, and tangent math
functions). Those of you who are familiar with
audio synthesis
are aware that other
types of sound waves are also used in sound design, such as the
saw wave
, which looks
like the edge of a saw (hence its name), and the
pulse wave
, which is shaped using
only right angles, resulting in immediate on and off sounds that translate into pulses (or
bursts) of audio.
Even randomized waveforms, such as noise, are used in sound design to obtain
edgy sound results. As you may have ascertained by using your recently acquired
knowledge of data footprint optimization, the more “chaos,” or noise, present in your
sound wave (and in new media data in general), the harder it will be to compress for a
codec. Therefore, more complex sound waves will result in larger digital audio file
sizes, owing to the chaos in the data.
Converting Analog Audio to Digital Audio Data: Samp-
ling, Accuracy, HD Audio
The process of turning analog audio (sound waves) into digital audio data is called
sampling
. If you work in the music industry, you have probably heard about a type of
keyboard (or even rack-mounted equipment) called a
sampler
. Sampling is the process
of
slicing
an analog audio wave into
segments
so that you can store the
shape
of the
wave as digital audio data, using a digital audio format. This turns an infinitely accur-
ate analog sound wave into a discrete amount of digital data, that is, into zeroes and
ones. The more zeroes and ones used, the more accurate the reproduction of the infin-
itely accurate (original) analog sound wave.
Each digital segment of a sampled audio sound wave is called a sample, because it
samples that sound wave at an exact point in time. The
sample accuracy
(resolution)
you want will determine how many zeroes and ones are used to reproduce analog
sound waves, so the
precision
of a sample is determined by the amount of data used to
define each wave slice's
height
. As with digital imaging, this precision is termed the
resolution
, or, more accurately (no pun intended), the
sample resolution
. Sample res-
olution is usually defined using
8-bit
,
12-bit
,
16-bit
,
24-bit
, or
32-bit
resolution.
Games mostly leverage 8-bit resolution for effects such as explosions, in which clarity
is not as important; 12-bit resolution for crystal-clear spoken dialogue and more im-
portant audio elements; and, possibly, 16-bit resolution for background music.
