DVD Technology Overview What is DVD? In December of 1995, nine major electronic companies (Toshiba, Matsushita, Sony, Philips, Time Warner, Pioneer, JVC, Hitachi, and Mitsubishi) agreed to promote a new optical disc technology for distribution of multimedia and feature-length movies. This new technology was called DVD (Digital Video Disc). This new medium was described as being capable not only of gigabyte storage capacity but also full-motion video (MPEG-2) and high-quality audio in surround sound. There are two types of DVD: DVD-Video and DVD-ROM. These reflect marketing channels, not the technology. The DVD drive for computer use will be a read-only drive referred to as DVD-ROM. Subsequently, the DVD computer drive family will be expanded with a one-time recordable version, referred to as DVD-R, and finally a rewritable version, referred to as DVD-RAM. DVD-ROM drives will be used with computers as an alternative to CD-ROM, providing over 7 times the storage capacity (4.7GB). The first drives, using a single-layer disc of 4.7GB, are currently available in Japan from several manufacturers including Toshiba, Philips, Sony and Hitachi. In 1997, dual-layer discs are expected to increase the disc capacity to 8.5GB. In the more-distant future, double-sided, dual-layer discs will increase DVD-ROM capacity to 17GB. The original DVD specification included broadcast-quality audio and video capabilities, along with full backward-compatibility with CD-ROMs, CD-Rs and audio CDs. DVDs capacity of 4.7GB per reflective layer seven times the storage capacity of a standard CD-ROM has an average data rate of 3MB/second. The one requirement all DVDs share is the MPEG-2 decoder, a piece of hardware that will come in the form of internal chips or adapter cards. Supporters of the DVD technology broke into competing factions and some of the issues that caused these factions are still unresolved. Hollywood concerns regarding intellectual property protection in DVD products may delay the introduction of DVD-Video. However, most developers are optimistic about the prospects of DVD. The DVD Standards DVD-ROM The DVD standard dual-layer discs, with a semi-reflective information layer underlying the regular fully-reflective layer will double information capacity. The DVD standard further allows for double-sided discs, with single or dual layers of data on both sides. All the discs will be the same diameter and thickness as current CDs. The DVD-ROM drive is expected to read existing CD-ROMs and music CDs and be compatible with installed sound and video boards. The Open Micro-UDF (Universal Disc Format) used by DVD-ROM is a further development of the CD-ROM file format ISO 9660. It allows programs with more features and more performance to be designed for all computer platforms. The DVD-ROM drive will read DVD movie titles using an MPEG-2 video boardrequired to decode the high resolution video format. For movie sequences (and still pictures), the MPEG-2 compression standard is specified. Accepted worldwide, MPEG-2 is already being used in professional applications. It is an open standard capable of delivering broadcast-quality pictures in conventional and wide-screen formats, together with up to 8 channels of CD-quality audio and 32 channels for sub-titles. MPEG-2 also supports MPEG-1, the standard presently specified for full-motion video on CD, and so creates the opportunity for backwards compatibility. DVD-Video As an entertainment product DVD-Video will be used for full length movies with up to 133 minutes of high quality video (MPEG-2 format) and audio. A single DVD-Video can play up a full featured Hollywood film (133 minute films are nearly 92% of all movies ever made) from one side. Picture quality is reported to be nearly three times better than VHS and demonstrably better than Laserdisc. DVD-Video also offers up to 8 different sound tracks, and 32 subtitles. DVD-Video also has the unique capability of offering movies in multiple formats all on a single disc. DVD-Video also contains a Pan and Scan version for a full screen picture on conventional television sets and a Letterbox version. Also included is a version that enables high resolution full screen display on widescreen televisions. DVD-Video provides 720 pixels per horizontal line compared to NTSCs current 240 pixels. This means that television pictures will be sharper and more detailed. Part of the DVD-Video specification includes Dolby AC-3 Digital Surround Sound. Eight separate audio channels can be programmed for Digital Surround Sound. DVD-Video also supports Dolby Pro-Logic Surround Sound, standard stereo, and mono audio. Users can randomly access any section of the disc and use slow-motion and freeze-frame during movie playback. Audio tracks can be programmed for as many as eight different languages, with graphic subtitles in 32 languages. DVD-R Just as CD-R drives can record a disc that appears to a CD-ROM drive as a pressed disc, the write-once DVD-R drives will record a 3.9GB DVD-R disc that can be read on a DVD-ROM drive. The first DVD-R drive is expected by mid-1997. DVD-RAM By the end of 1997, the rewritable DVD-RAM drive should become available. DVD-RAM drives will read and write to a 2.6GB DVD-RAM disc, read and write-once to a 3.9GB DVD-R disc, and read a 4.7GB/8.5GB DVD-ROM disc. Also, it is expected that a DVD-RAM disc will be readable on both the DVD-R and DVD-ROM drives. DVD Specifications Disc Diameter: 5 inches Disc Thickness: 1.2 mm Memory Capacity: 4.7 gigabytes/single side Track Pitch: 0.74 micrometer Wave Length of Laser Diode: 650 nanometer/634 nanometer Numerical Aperture: 0.6 Error Correction: RS-PC (Reed Solomon Product Code) Signal Modulation: 8-16 Data Transfer Rate: Variable speed transfer at an average rate of 4.69 megabits/second for image and sound Image Compression: MPEG-2 digital image compression Audio: Dolby AC-3 (5.1 ch) LPCM for NTSC and MPEG Audio LPCM for PAL/SECAM (a maximum of 8 audio channels and 32 subtitles channels Running Time (movies): 133 minutes a side (at an average data rate of 4.69 megabits/second for image and sound, including three audio channels and four subtitle channels File Management Structure: Micro UDF and ISO-9660 DVD Outlook The success of CD-Audio (compact discs) subsidized the creation of a new digital publishing medium, CD-ROM. CD-ROMs success will help establish DVD-ROM, which will in turn subsidize the creation of a new digital entertainment medium, DVD-Video/Audio. DVD, like compact disc audio, will probably not boom overnight. However, it is expected that software publishers will welcome the increased capacity offered by DVD-ROM. New interactive multimedia titles and games will most likely lead the way making use of the increased capacity and better quality motion video. It is generally thought that the DVD-ROM market will develop faster than DVD-Video. There are several reasons for this. The OEM price of a DVD-ROM drive will be much lower than a complete DVD-Video player. An OEM price of approximately $200 for a DVD-ROM drive is expected in 1997, especially with the decision by Intel to ship its MMX machines with built-in DVD-ROM drives. It is estimated that by the year 2000, approximately 10 percent of all the 250 million drives sold will be based on DVD.