1 CP586 © Peter Lo 2003 Multimedia Communication Video Terminology

CP586 © Peter Lo Summary Examine analog video Define terminology used in digital video. Discuss digital video characteristics. Compare two types of digital video compression and define the term “key frame”. List a variety of video standards.

CP586 © Peter Lo Analog Video Each frame of video is represented by a fluctuating voltage known as an analog wave form. A composite signal has brightness, colour and synchronisation elements combined in the one signal. NTSC, PAL and SEACAM are the three most widely used composite video signals.

CP586 © Peter Lo Analog to Digital Video NTSC, PAL and SEACAM signals are analog (wave based). Computers store video in a digital format. The process of digitising video is known as capturing or sampling.

CP586 © Peter Lo Terminology High Definition Television (HDTV) Component video stores colour, brightness and sync information as separate signals. Generational loss occurs because the signal deteriorates from one generation to the next. Digital video is not subject to generational loss because each copy is identical to the parent or original.

CP586 © Peter Lo Digital Video Characteristics Digital video consists of several frames displayed in quick succession. A frame has similar characteristics to that of a digital image Frame Rate. Frame size. Colour depth or resolution.

CP586 © Peter Lo Compression Inter-frame compression This method of compression uses redundancy techniques to remove repetition between frames. This involves the use of a key frame. Intra-frame compression This method of compression stores each individual frame as a discrete image. Each of these images are then compressed individually.

CP586 © Peter Lo Key Frame Inter-frame compression is perfect when there is a limited amount of background action, for example a video conference. Video capturing software allows you to set the number of Key frames. Each subsequent frame of the digital video is compared to the key frame and only the changes are stored which reduces file size.

CP586 © Peter Lo Computer Animation 3DFX can be used to generate animation. 3DFX can create video file (.AVI) for your assignment. 3DFX is based on an object orientated model. The wire frame objects can be given properties, paths and behaviours. 2D or Path animation can be created in ToolBook.

CP586 © Peter Lo JPEG JPEG stands for Joint Picture Experts Group. This standard was developed for still images and has a compression rate of 20:1. It can be used for intra-frame compression. Files in this format have a.JPG or.JPEG extension. What type of compression (ie. Lossy or lossless) does JPEG use?

CP586 © Peter Lo MPEG Short for Moving Picture Experts Group, and pronounced m-peg, a working group of ISO. The term also refers to the family of digital video compression standards and file formats developed by the group. Files in this format have a.MPG or.DAT extension. MPEG provides a 50:1 compression rate.

CP586 © Peter Lo Video for Windows A format developed by Microsoft Corporation for storing video and audio information. Files in this format have a.AVI extension. AVI files are limited to a 320 x 240 resolution, and 30 frames per second, neither of which is adequate for full-screen, full-motion video.

CP586 © Peter Lo QuickTime The QuickTime video and animation system developed by Apple Computer. QuickTime is built into the Macintosh operating system and is used by most Mac applications that include video or animation. Files in this format have a.MOV extension.

CP586 © Peter Lo Real Video A streaming technology developed by Real Networks for transmitting live video over the Internet. Real Video uses a variety of data compression techniques. Files in this format have a.RAM extension.

CP586 © Peter Lo ActiveMovie A new multimedia streaming technology developed by Microsoft. ActiveMovie is already built into the Internet Explorer browser will be part of future versions of the Windows operating system. Supporting most multimedia formats, including MPEG, ActiveMovie enables users to view multimedia content distributed over the Internet, an intranet, or CD-ROM.