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 Example: Istockphoto

Some technical details  Light is converted into an electric signal by a sensor called a CCD  Good cameras have 3 CCD’s (RGB)  Component video is split into two separate chroma channels and a brightness channel  Composite video has all signals mixed together and carried on a single cable

Broadcast video standards  NTSC: Used in USA, Japan and some other countries  PAL: Europe, Australia, South Africa  SECAM: France, Russia and few other countries  HDTV: High Definition TV. 16:9 aspect ratio.

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 Formats

Video frames of MPEG compression

(Net videos, CD-ROM videos, oldish) (DVD, digital TV, HDTV) (multimedia, digi-tv, mobile)

(Edition software) (Post production software)

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?  metria/skiaskopia/ metria/skiaskopia/

(Animation software), Blender. (Camtasia Studio, Captivate)

Example:  2D Visualization of nuclear power plant components  3D visualization of a wood pressing machine