VIDEO TECHNOLOGIES Iwan Sonjaya ST MMT MT Computer

VIDEO TECHNOLOGIES Iwan Sonjaya, ST. MMT, MT Computer and Informatics Engineering Dept. State Polytechnic Of Jakarta

Video Technologies ANALOG DIGITAL

Analog Video Technology n Analog means ?

Analog Video Technology Analog Formats n Videotape u VHS (remember BETA? ) u 8 mm n Laserdisc n Familiar? Obsolete? n Why discuss?

Analog Video Technology n Videotape n Laserdisc

Video (Analog Tape) Positives n Familiar, common hardware u n n VCRs, players, camcorders Perceived image “quality” u. Impact of screen size Full color depth (~ 24 -bit)

Video (Analog Tape) Positives n n n RECORDABLE & erasable Inexpensive hardware & tapes Can be digitized

Video (Analog Tape) Negatives n Quality of NTSC n n (standard N. Am. television) TV vs. Monitor Fundamentally linear u Hard to use segments u Example(s) u Computer control ? ?

Video (Analog Tape) Negatives n Limited manipulation u Costly hardware to edit u Quality loss by generation n Distance distribution u Limited rapid sharing u cf. video conferencing

Analog Video Technologies n Videotape n Laserdisc (Laser videodisc)

Laserdisc (Analog) Overview n Precursor to DVD n Advantages & Disadvantages n Laserdisc technology n Advanced systems

Laserdiscs +/Advantages n n n Higher video quality Multi-channel sound Double-sided Still frame & special effects Potential for random access u Non-linear = hyper

Laserdiscs +/Disadvantages n n n ‘Special’ hardware u Unfamiliar at home Bulky Cost of hardware u vs VCR (or DVD) n No local recording

Video Technologies ANALOG DIGITAL

Video n Video, like sound, is recorded and played an as analog signal n Analog video must be digitized in order for it to put into a multimedia file n Digital video has many advantages, but file size is important

Video n Several elements determine file size: u. Frame rate u. Image size u. Color depth n To determine file size use the following formula: u. Frames per second X image size X color depth / 8 = file size

Video Compression and Editing n There are two types of video compression u Lossless – preserves the exact image throughout the compression u Lossy – eliminates some of the data in the image (provides greater compression ratios than lossless) u Remember – there is always a trade off, file size versus image quality

n Video on the Internet There are two types of video transfer over the Internet u HTTP (Hypertext Transfer Protocol) – downloads the entire video to the hard drive on the user’s computer u RTSP (Real-Time Streaming Protocol) – is a continuous-playing, streaming technology in which the user’s computer is in constant contact with the server playing the video

Video Tips Color depth Reducing the color depth to less than 256 colors gives a markedly poorer-quality image. Frame rate Reducing the frame rate to less than 15 frames per second causes a noticeable and distracting jerkiness that is usually unacceptable. File size A technique for reducing file size is to minimize the use of video in the image that appears on the screen – that is, to create video only for the parts of an object that are changing, such as a flickering candle. The video could be played over and over to create the motion of a flickering candle.

Video Tips Display size In most multimedia titles, you do not need to show full-screen video. The video can be played in a window that can be as small as one-fourth or even one-sixteenth the size of the screen. Conclusion: Changing the image size and compressing the file become the primary ways of reducing file size. In most cases, a one-quarter screen image (320 X 240), an 8 bit (256 colors) color depth, and a 15 frames per second frame rate are acceptable in a multimedia title.

Digital Video What is it? n Most commonly: u Analog video – digitized u Computer files n Newer technology: u Original digital video (DV) u Bits on a digital tape

Creating Digital Video Hardware n Analog Digitizing Gear u $50 - $1000+ u Internal, external, both n n n Digital camcorder + IEEE 1394 u “Firewire” or “i Link” Many digital ‘still’ cameras u Highly variable results PC / web cameras (“golf balls”)

Creating Digital Video Software n Comes with hardware n Capture, then edit u Not necessarily same software n n Varied features, e. g. formats Varied learning curve u Match to need & skill u i. Movie / Movie Maker to Premier

Other Digital Video Sources n n n Clip video (CD / Web) Download from web sites u Varies by video format “Screen capture” software u Camtasia, Cam. Studio, etc. n n Morphing software Animation software u Flash, et al – beyond our scope n Class web page has links

Digital Video Concepts n Video = “frames” u How many / sec? n n Apply still image file size concept Video = ++MB u Forget KB

Digital Video Concepts n Image Size (‘window’ on screen) u Pixel dimensions n Common Sizes u 160 x 120 (‘ 1/16’) u 320 x 240 (‘ 1/4’) u 640 x 480 (‘full’ screen) u 720 x 480 (DVD, ‘wider’ screen) u What does a viewer really see?

Digital Video Concepts DV File Size Factors n Image pixel dimensions u Just like still images n n FPS u Frames per second u Number required? Color depth (bits) u Increasingly, no option

Digital Video Concepts DV File Size Factors u. Video (file) format (more later) Quick. Time / AVI / WMV l MPEG (mpg) l Streaming u CODEC l Compression / decomp algorithm l Sometime selectable (cf. audio) l u Audio quality l Limited impact

Digital Video Benefits n n Inexpensive hardware to create Edit electronically with software (non-linear editing) Just another (large) file = transmission potential u FTP, email, or on web pages u Keep file size down! u Or stream it More flexible use

Digital Video Issues u Image quality (e. g. jaggies) u Limited resizing (pixels, jerky) u Differing formats / architectures u Non-standard compression schemes Broadway AVI & M-JPEG l Codec compatibility / availability u Storage requirements / downloads l

Impact of File Size 1 min video can take minutes to download

DV Formats n Quick. Time (mov) u Background / compatibility n Video for Windows (avi) n WMV n MPEG (mpg, mp#) u Current standard ? u Video CD / DVD n Streaming competition (later) u Real vs MS vs QT

‘Exotic’ DV n VCD (Video CD) u u Mpeg-1 Common outside US n QTVR u u Lighthouse (HS) Orlando Art Museum

Other Digital Video Topics Creating digital video u. Capturing u. Editing u. Producing n DVD n Streaming n