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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

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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

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

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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)

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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, on 5.11.2009

http://en.wikipedia.org/wiki/Comparison_of_container_formats

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(Net videos, CD-ROM videos, oldish)

(DVD, digital TV, HDTV)

(multimedia, digi-tv, mobile)

(Edition software)

(Post production software)

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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

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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 you 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

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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?

money issues

time issues

artistic issues

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

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