ion (although it supports Dolby AC-3 audio and not MPEG-2 audio). DVDs use laser technology to store up to 17 gigabytes (GB) of data, enough for nine hours of studio-quality audio and video. MPEG-2 Parts The MPEG-2 ISO/IEC 13818 volume consists of a total of eight parts, 1-7 and 9 (part 8 was withdrawn). Part 1-SYSTEMS (13818-1). Part 1 addresses how one or more elementary streams of video, audio and data are combined into single or multiple streams suitable for MPEG Family of Specifications storage and transmission. These streams take one of two forms, the Program Stream and the Transport Stream. Each is optimized for a different set of applications. The Program Stream is similar to MPEG-1 Systems Multiplex. It results from combining one or more Packetized Elementary Streams (PES), which have a common time base, into a single stream that run at between 3-15 Mbps. The Program Stream is used for DVD encoding. The Transport Stream combines multiple PES with one or more independent time bases into a single stream. Elementary streams sharing a common time base form a program. The Transport Stream is designed for use in environments where errors are likely (broadcast and telecommunications). Transport stream packets are 188 bytes long. Part 2-VIDEO (13818-2). Part 2 builds on the video compression capabilities of the MPEG-1 standard to offer coding tools. These have been grouped in seven profiles to offer different functions. The first five were approved with the standard in November of 1994. The sixth profile (the 4:2:2 Profile) and the seventh (Multiview Profile) were added in 1996. Part 3-AUDIO (13818-3). Part 3 is a backward compatible multi-channel extension of the MPEG-1 Audio standard. Part 4-COMPLIANCE TESTING (13818-4). Part 4 of MPEG-2 corresponds to Part 4 of MPEG-1. It was approved in March 1996. Part 5-SOFTWARE SIMULATION (13818-5). Part 5 of MPEG-2 corresponds to Part 5 of MPEG-1 and was approved in March 1996. Part 6-DIGITAL STORAGE MEDIUM COMMAND AND CONTROL (13818-6). This part defines a syntax for co