APPENDIX 401low compression ratios, such as 2:1 (every one original frame can beresized down by half). Once you get up to higher ratios such as 10:1 oreven 100:1, noticeable degradation occurs and you would be better offusing another scheme such as MPEG.MPEGMPEG has grown out of JPEG but added more sophisticated interframetechniques to save only the differences between key frames – called Iframes. Currently there are two standards: MPEG-1 and MPEG-2. MPEG-1 is designed to produce ½ screen (352x240) 24-bit color, 30 frames persecond video running at approximately 170kbps. MPEG-2 is designed forfull screen (720x480) 24-bit color, 60 field video running at anywherebetween 500kbps to 2mbps. MPEG-2 is set to become the standard forhigh quality video playback, particularly over the newer DVD discs.MPEG.NowThe MPEG.Now software codec promotes superior quality transcoding andreal-time encoding for MPEG 1 and 2. It supports real-time features (e.g.,direct MPEG capture from IEEE-1394 interfaces).Aspect RatioAspect ratio is the relative horizontal and vertical sizes of the screen orimage (usually expressed as width:height). If an image has an aspect ratio of4:3, it means that it is wider than it is tall (which, of course, is mostly thecase for television). It is best to maintain the image’s aspect ratio whenadjusting its size to avoid distortion. It could also be used to represent thedimensions of a particular image’s display resolution (e.g., if we have aresolution of 800x600, the aspect ratio is 4:3, or if we have a resolution of720x480, then the aspect ratio is 16:9). The standard aspect ratio fortraditional television sets and computer monitors is 4:3 while the aspect ratiofor high-definition, wide-screen digital systems is 16:9. More systems canread 4:3. For the sake of general viewership, 4:3 would be the most advis-able display aspect ratio to use.
