Section Two: Video Encoding Standards
MPEG-1 (ISO/IEC 11172)

The first digital video and audio encoding standard, MPEG-1, was adopted as an international standard in 1992 to provide digital video at bit rates up to 1.5 Mb/sec. (The standard actually scales higher than 1.5 Mb, but 1.5 Mb is the accepted "sweet spot" for MPEG-1.) The impetus for the standard was to provide encoding and playback of VHS-quality digital video for CD-ROM playback. MPEG-1 is a progressive video sequence encoding standard. The standard implementation for MPEG-1 (known as "constrained bit stream") supports 352 pixels x 240 lines/sec at 30 frames/sec and requires 1.5 Mbit/sec bandwidth for transport. MPEG-1 compression relies on the considerable redundancy of information within and between frames to compress a video object without significantly compromising the integrity of the information it contains.

Video contains spatial, spectral and temporal redundancies, which may be compressed without significant sacrifice in meaning. The encoding techniques in MPEG-1 involve compression based on statistical redundancies in temporal and spatial directions. Spatial redundancy is based on the similarity in color values shared by adjacent pixels. A red sweater in a video frame will generally possess a uniform color value, with little or no perceptual variation from one pixel to the next. MPEG-1 employs intraframe spatial compression on redundant color values using DCT (discrete cosine transform).