Glossary (continued)
Video
AVI: Short for Audio Video Interleave, the file format for Microsoft’s Video for Windows standard. See under Video for Windows.
DivX: Is a video format that is MPEG-4 compliant and widely used on the Internet for encoding video files.
MPEG: Short for Moving Picture Experts Group, and pronounced “empeg”. MPEG generally produces better-quality video than competing formats. MPEG achieves high compression rate by storing only the changes from one frame to another, instead of each entire frame. MPEG uses a type of lossy compression, since some data is removed. However, the reduction in the resulting video quality is minimal. There are three major MPEG standards: MPEG-1, MPEG-2 and MPEG-4.
•The most common implementations of the MPEG-1 standard provide a video resolution of 352-by-240 at 30 frames per second (fps). MPEG-1 is used with Video CDs (VCD) and results in video quality slightly below the quality of a VCR video.
•MPEG-2 offers higher resolution with CD-quality audio. This is sufficient for all major TV standards, including NTSC, and even HDTV. MPEG-2 is used by DVDs. MPEG-2 compresses a 2 hour video into a few gigabytes of data on a single disc.
•MPEG-4 is a video compression standard based on MPEG-1 and MPEG-2. Videos encoded with MPEG-4 technology are considerably smaller than videos encoded with MPEG-1 or 2. MPEG-4 was standardized in October 1998.
QuickTime: An audio and video compression technology developed by Apple Computer and is widely supported on Macintosh and Windows PC computers. The latest QuickTime implementation is MPEG-4 compliant.
XviD: XviD is an ISO MPEG-4 compliant video codec. It’s an open source project which is developed and maintained by many people from all over the world.
