low-end, mass-market applications. I- frames anchor picture quality, because ultimately P and B-frames are derived from them. P-frames are the least demanding of the three, in terms of their impact on a decoder. MPEG 1-ISO/IEC 11172 The official title of the ISO/Ice's MPEG-1 specification is, "Coding Of Moving Pictures And Associated Audio For Digital Storage Media At Up To About 1.5 Mbps." It was originally approved as a three-part specification in October of 1992. Later, two additional parts were added, one in 1994 and one in 1995. MPEG-1 encoded video is optimized for playback on computers and set-top boxes. MPEG-1 uses progressive (non-interlaced) scanning to provide a typical picture resolution of 352H-by-240V pixels (although the resolutions can vary). Images are displayed at 30 fps (in North America and Japan only) and 25 fps. The MPEG-1 data rate is 150 Kbytes (not Kbps). This speed, which matches the data rate delivered by a single-speed CD-ROM player, is also compatible with T-1/E-1 network speeds. Special MPEG-1 compliant chips provide near VHS-quality desktop video (with CD- MPEG Family of Specifications ROM quality stereo sound) at data rates of 150 Kbytes. This data rate conforms to T1/E1 speeds and matches the data rate from a standard, single-speed CD-ROM player). The five MPEG-1 parts are as follows: Part 1-SYSTEM (IS 11172-1). This part describes the syntax used to synchronize and multiplex audio and video signals. These signals can be transported over digital channels and/or stored as digital media. Part 1 also includes the syntax for synchronizing video and audio streams. Part 2-VIDEO (IS 11172-2). This part describes compression of non-interlaced video signals. It specifies the header and bit stream elements for video and identifies the algorithms (semantics) used to code and compress video. Video handles the image by dividing it into nested layers. At the highest layer (the picture layer) frame rates and resolutions are defined. Below the picture layer comes slices, macroblocks, blocks, samp