But, how does all of this really work? Zettl Chapter 4

But, how does TV work? Persistence of vision A series of still pictures scanned so quickly that our eyes see it as movement. Philo Farnsworth- Inventor of Tv

Scanning Principal  Let’s start at the beginning –The older CRT TVs had an electron gun that drew the video image one line at a time. It went back and forth until all the lines of the screen were drawn...\How Television Works.wmv Page 65

Pixel  Let’s break the image down to it’s lowest component…the pixel  It’s one dot of the image  The more pixels the better the image

Scanning Systems Scanning Systems  Progressive –Scans every line from top to bottom at the same time –Starts at the top left and goes down to the bottom –One complete scan is called a frame –Refresh rate ( how often the beam jumps back to scan another frame is usually 60)

Scanning Systems  Interlaced –The odd number lines are scanned first and then the beam goes back to scan the even numbers –The beam scans the image 2 times to get a complete image –One scan is called a field –Two scans is called a frame

Digital Scanning Systems  480P –Uses progressive scanning  720P –Uses progressive scanning –Refreshes at 1/60 –True HD  1080i –Uses interlaced scanning –Refreshes at 1/60 which gives 30 frames per second

Refresh or Frame Rate Refresh or Frame Rate  Frame = all lines have been scanned  30 frames in 1 second – video  24 frames in 1 second – film Television Production: How The TV Process Works

Broadcast Systems  NTSC – USA & Japan  Pal – Most of Western Europe  Secam – Africa & Eastern Europe File:PAL-NTSC-SECAM.svg - Wikipedia, the free encyclopedia File:PAL-NTSC-SECAM.svg - Wikipedia, the free encyclopedia

Aspect Ratio  Need to understand for composition  Size of picture  4 X 3 –Standard TV –Could be analog or digital  16 x 9 –HDTV & Digital Television Production: World Television Standards and HDTV/DTV

Different types TV’s  CRT  LCD  Plasma  Liquid Crystal Display  Projection  DLP

Analog vs. Digital  Analog is “old-school” – keeps it like the original Digital turns the video signal into computer data  USA just turned to digital signal – can you say when it happened?

Compression   HDV & HDTV information is so large that it must be compressed   Think of it like folding a shirt into a smaller size to squeeze it into your drawer   CODECS – several types of compression

Streaming   Sending a video signal over the internet   Future of television   Already started

Government Agency  FCC  Federal Communication Commission  Regulates TV Industry Federal Communications Commission

How does it get to your house?  Depends on how you receive your TV  Cable vs. Satellite vs. Internet (page 414)  Refer to the beautiful drawing on the board

Distribution Methods  Video tape  DVD  Internet  File Sharing (quicktime or other codec)  Cable TV  Consumer Satellite (Direct TV)  Network Satellite  Microwave

Walter Cronkite would say... “And that’s the way it is!”