Digital Video 1

Producing Digital Video Video capture Involves digitizing an analog source Editing Linear editing Non-linear editing Playback The stored data must be fetched, processed, and converted to analog signals for video display and speakers 2

Advantages and Disadvantages of Digital Video Scalable to different playback systems Random access to frames Nonlinear editing More playback options Potential for interactivity Disadvantages Special hardware/software needed for production High playback and storage requirements

Capturing Video Sequences Frame Capture Analog color frames to sampled converted color video frames Digitizing Sampled converted color video frames to sampled digitized frames Compression Sampled digitized frames to compressed data

Digital Video The Entire Process Illustrated

Basic Desktop Video System Analog source Camcorders, video tape players Video Capture Card Breakout box CPU Secondary storage Monitor Editing and Playback control Require software support

Properties of Digital Video Frame rate Number of frames displayed in one second (fps) Full motion video at 24 fps Frame Size Number of horizontal and vertical pixels Color Resolution Number of bits used to represent color

Digital Video: Size Calculation f = frame size ( width * height) r = frame rate (frames per second) c = color depth (in bytes) t = time in seconds Size of Digital Video = f * r * c * t

Calculation Example

Compression: Coping with Large Files Compression is an encoding process that filters the original file in several successive stages 4

Other Methods for Reducing Demands Frame rate adjustment adjusts for with slower CPUs helps keep video and audio synchronized Lower resolution on individual frames sometimes used in conjunction with smaller display window 5

Editing Digital Video Clip Logging Assembling Transitions dissolves wipes, etc. Rotoscoping Compositing keying titling 9