Video
Queries begin.
4.1. What is the aspect ratio of the NTSC standard screen? What does that mean? Is the NTSC format the same as a VGA computer screen?
4.2. NTSC broadcasts (approximately) 30 frames per second, but the screen flickers 60 times per second. Why? How is this magic achieved? (Ignore what the text says about a display refresh buffer; this is done for computers but NOT in a TV set!) Truth begins with "A full TV picture...." on page 85.
Film runs at 24 frames a second but flickers at a frequency of 96 hz. How is this done? (Answer will come in the lecture, if you don't find out somehow beforehand.)
The text mentions Showscan technology. I think this is the same as IMAX; but in any case, IMAX does run at 60 frames per second. It uses up a LOT of film that way.
The text's explanation of video transmission is not wonderfully clear. Give it a try, but I'll actually lecture about this material in class. The following query can only be answered after the lecture.
4.3: Explain the concept of "degrees of freedom" of a system. Illustrate by a discussion of color space in terms of RGB, HLS ("Hue, lightness, saturation"), YUV and YIQ color systems.
Once the color scheme is chosen, you still have to decide how to record and transmit it. The three systems in widespread use:
NTSC - North & South America & Japan. 525 lines at 60 hz. Total of about 6 mhz stored, 5 transmitted.
PAL - most of the rest of the world. Europe & England & India & China. 625 lines, 50 hz. 8 mhz; higher quality signal.
SECAM - the French system, because they have to be different. Eastern Europe, parts of Africa. Same lines & hz as PAL.
High Definition TV - the great analog disaster in Japan. This story will be told in class. This part of the text is obsolete.
Computer Based Animation. Video is all about pixel images, but animation is mostly about geometric representations - 2d or 3d - which are rendered into images in the latter stages of production.
Animation languages: forget it. Seldom used. Most animation is done with sophisticated software packages such as Alias/Wavefront. We'll have a demo/video thereof.
The stages of computer animation go something like this:
1. Scriptwriting
2. Storyboarding
3. Animatic (use of storyboards to tell the story, with a rough sound
track.)
4. Modeling - the most tedious portion. Every object in every scene
is CAD-modeled.
5. Rendering - the most compute-intensive portion. This involves
- lighting, which can be a very complex process
I will show you the results of last year's CREAT Senior Project concerning
animation.
More QUEST Opportunities
DVD - (Digital Videodisk.) - is regarded as the successor to today's
CD format. The disks are the same size but can store a whole 2 hour movie.
We need someone to go find papers about DVD and prepare to summarize them
for us. Questions to be answered would include - which video scheme is
used? (Text says DV-I used YUV, and DVI is a predecessor to DVD.)