[JAVA][Beginning Java 8 Games Development]

Chapter 5 ■ An Introduction to Game Design: Concepts, Multimedia, and Using Scene Builder
frame in a video data stream. This is why a talking head video will encode better than a video in which every pixel
moves on every frame (such as video that uses fast camera panning, or rapid field of view [FOV] zooming).
A key frame is a setting in a codec that forces that codec to take a fresh sampling of your video data assets every
so often. There is usually an auto setting for key frames, which allows a codec to decide how many key frames to
sample, as well as a manual setting, which lets you specify a key frame sampling every so often, usually a certain
number of times per second or over the duration of the entire video (total frames).
Most codecs usually have either a quality or a sharpness setting (a slider) that controls the amount of blur
applied to a video frame before compression. In case you are not familiar with this trick, applying a slight blur to your
image or video, which is usually not desirable, can allow for better compression, as sharp transitions (edges) in an
image are harder to encode, taking more data to reproduce, than softer transitions. That said, I would keep the quality
(or sharpness) slider between 80 percent and 100% percent and try to reduce your data footprint using one of the
other variables that I have discussed here, such as decreasing the resolution, frame rate, or bit rate.
Ultimately, there will be a number of different variables that you will need to fine-tune to achieve the best
data footprint optimization for any given digital video data asset. It is important to remember that each video asset
will look different (mathematically) to a digital video codec. For this reason, there can be no standard settings that
can be developed to achieve any given compression result. That said, experience tweaking various settings will
eventually allow you to get a feel, over time, for the various settings that you have to change, in terms of the different
compressions parameters, to get the desired end result.
Digital Audio Concepts: Amplitude, Frequency, Samples
Those of you who are audiophiles know that sound is created by sending sound waves pulsing through the air. Digital
audio is complex; part of that complexity comes from the need to bridge analog audio technology, created with
speaker cones, with digital audio codecs. Analog speakers generate sound waves by pulsing them into existence. Our
ears receive analog audio in exactly the opposite fashion, catching and receiving those pulses of air, or vibrations with
different wavelengths, and then turning them back into data that our brain can process. This is how we “hear” the
sound waves; our brain then interprets the different audio sound wave frequencies as different notes, or tones.
Sound waves generate various tones, depending on the frequency of the sound wave. A wide, or infrequent
(long), wave produces a low (bass) tone, whereas a more frequent (short) wavelength produces a higher (treble) tone.
Interestingly, different frequencies of light will produce different colors, so there is a close correlation between analog
sound (audio) and analog light (color). There are many other similarities between digital images (and video) that will
also carry through into your digital new media content production, as you will soon see.
The volume of a sound wave will be determined by its amplitude, or the height (or size) of that wave. Thus,
frequency of sound waves equates to how closely together the waves are spaced, along the x axis if you are looking at
it in 2D, and amplitude equates to how tall the waves are, as measured along the y axis.
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.
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