Video
Using video
Carefully planned, well-executed video clips can make a dramatic difference in a multimedia project
Use video only when all other methods (text, still images) are not enough; don’t use it just because it’s possible
Obtaining video clips
Shoot your own clips Buy footage; this can be a nightmare
since the licensing rights and permission may be difficult to obtain
On some projects you have no choice but to pay the price for required footage
Example: Istockphoto
Video compression Even a small 10-second clip of full-motion video
requires transfer of an enormous amount of data in a very short amount of time
One frame of 24-bits requires almost 1MB of computer data, 30 seconds will require a one gigabyte
Full-size, full-motion video requires that the computer deliver data at about 30MB per second
This technological bottleneck is overcome using digital video compression schemes or codecs (coders/decoders)
Video compression
A codec is the algorithm used to compress a video for delivery and then decode it in real-time for fast playback
All popular codecs employ lossy compression algorithms
Popular codecs: MPEG, Divx, RealVideo, DVI/Indeo, Cinepak
Typical filename extensions
avi - Audio Video Interleave mp4 - MPEG-4 Part 14 or MP4 file format mkv & mka - Matroska Multimedia Container mpg & mpeg - Moving Picture Experts Group flv - Flash Video wmv, wma & asf - Advanced Systems Format mov - Apple Quicktime Movie rm - Real Media File 3gp - 3GPP Multimedia File vob + ifo - Video Object & DVD Information File
Wikipedia: Comparison of Container Formatshttp://en.wikipedia.org/wiki/Comparison_of_container_formats
Video frames of MPEG compression
Use of video in multimedia
(good video is illustrative)
(use static video, near shots)
(less than 1 min clips)
(video is confirming and creates mental images)
(divide long video into clips with interactivity)
Animation
Principles of animation Animation is possible because of a
biological phenomenon known as persistence of vision and a psychological phenomenon called phi
An object seen by the human eye remains chemically mapped on the eye’s retina for a brief time after viewing
Combined with the human mind’s need to conceptually complete a perceived action, this makes it possible for a series of images to blend together into a visual illusion of movement
Computer animation Computer animation programs typically use
layers, keyframes and tweening techniques These methods are commonly used also
with traditional animations that are done without computers
You can usually set your own framerate, but the rate at which changes are computed and screens actully refreshed will depend on the power of your display platform and hardware
The smaller the object, the faster it can move
Animation file formats
Some file formats are designed specially for animations; they can be often ported among applications and platforms
Popular animation formats: Director (.dir and .dcr), 3D Studio Max (.max), Windows Audio Video Interleave (.avi), Machintosh Quicktime (.mov), Motion Video (.mpg), Flash (.swf)
Video vs. animation Video includes something that is real;
an animation has no limits
When to choose video, when animation?
http://streams.metropolia.fi/old/optometria/skiaskopia/
Example:
2D Visualization of nuclear power plant components
3D visualization of a wood pressing machine
