The Smart Solution for MPEG-2 Editing Video Technology & Practice DVD, Authoring and 601 DVD Video- An Introduction MPEG-2, along with DV is fast becoming the de facto video compression standard in the age of digital video. The first and most well- known application for MPEG-2 is as a video format for DVD. Although DVD still has to make its breakthrough in Europe in particular, it is already apparent that this 'Super-CD' will have the same success in the storage and video sector as the CD has had in the audio sector. Until recently, the production of DVD video was only feasible for projects in the magnitude of a Hollywood film. However, new low-{;ost equipment for editing in MPEG-2, compiling content (called authoring) and mastering will change all this in the near future. What's behind "DVD"? What features and possibilities can be used for what application and what is already possible today? The Universal Super-CD As a universal medium, DVD ('Digital Versatile Disk') aims, on the one hand, to become the successor of the CD-ROM as a storage medium for PCs and, on the other hand, to replace the VHS tape. When such a universal medium is defined, it is practically unavoidable that an almost infinite number of parameters emerge, which in the case of DVD have given rise to various sub-formats and sub-definitions. DVD-ROM, DVD-R, DVD-Video, DVD-RAM. In general, there is a difference whether the DVD is to be used as a storage medium for PC data or as an interactive medium. Depending on the intended use, the format and compatibility of the DVD must be taken into account. DVD-ROM The DVD-ROM is the base for DVD developments. Data cannot be written on to it but it is pressed in the factory from a master. Similar to the CD it is scanned by a laser without being touched and thus it has a virtually infinite service life. Unlike the CD there are double sided and two-Iayer definitions for the DVD-ROM, both of which double storage capacity. Thus, there are definitions for four different versions. DVD 5 is most commonly used at present. The DVD-ROM can be written {like the CD-ROM) with any PC data, which can then be read again by any suitable PC. The type of data is irrelevant as the DVD-ROM merely functions as a large data carrier. However, the DVD-ROM can become a DVD video through the use of a special format {and the corresponding contents). The DVD-ROM can be played back in both DVD-ROM and DVD-RAM drives in a PC. DVD-RAM The DVD-RAM is a completely different development from the DVD-ROM. The goal was to develop a medium that could be overwritten many times and was as easy to handle as a CD. At present the capacity of the DVD-RAM is limited to 2.6 GB and it can only be used as a 'sealed package', i.e. with a permanent protective cover ('caddy'). With current technology a DVD-RAM can only be read in a DVD-RAM drive in a PC (which can however also read DVD-ROMs). Therefore, the DVD-RAM is suitable as a fast, large removable medium but not as a medium to create DVD videos. Theoretically, a DVD-RAM can also be formatted as a DVD video but in practice there are not yet any DVD players that can read DVD-RAMs. In the future new technology should make DVD-RAM compatible with DVD-ROM or DVD video. DVD-R DVD-R, which can be written to once, has a special status. In contrast to DVD-ROMs and DVD Videos produced on high-end machines and to incompatible DVD-RAMs, DVD-Rs can be produced with a PC using a DVD-R device (similar to CD-R). Both DVD- ROM and DVD video formats can be used. The DVD-R thus produced is compatible with DVD drives and DVD players (as DVD video). The capacity of the DVD-R is currently limited to 3.9 GB. Developers are working on a version with 4.7 GB storage capacity, which would then be 100% equivalent to DVD 5. DVD Video In the mid-term DVD video is intended as a replacement for the VHS tape. The conditions are favorable but only on the player market (e.g. video rentals). At present, functionality as in a VHS video recorder is unthinkable. Such equipment for repeated recording is still at the prototype stage. The key advantage of DVD video is its virtually unlimited service life. Even when it is played back for the hundredth time, its quality is still as good as the first time. A DVD video is a DVD-ROM, -RAM or -R with a special format -equivalent to an audio CD, which in turn is a specially formatted CD- ROM. This format includes video, audio and control information. For example (provided the relevant information is available) 15029 Wood,""ille-Aodmond Ad. Wood,""I1'o. WA 9.072 ToC 4253542002 .Fax 4253542005 wwwfasfmu'fimodiocom it is possible to choose among different camera angles, several languages or various subtitles. Naturally, just like with audio CD, it is also possible to jump between separate video sequences and chapters, provided this was taken into account during creation. With standard DVD players all features of DVD video can be used. With a PC, the DVD video can only be played back if the appropriate decoder hardware for video and audio is available. The Technology Certain parameters are defined for DVD video which allow both interactive Hollywood productions as well as simple films consisting of just one video/audio sequence to be recorded on a DVD. Video format Common to all DVD videos is the video format: MPEG-2 in the version MP@ML. The data rate can be up to 9.8 Mbps {including all audio, subtitle and other data). Typically, a rate of 2 to 8 Mbps is used, which more or less lies between VHS and good television quality. For example, a 135 minute movie fits on to a DVD-5 with quality that cannot be matched by VHS. Page ratios of 4:3 and 16:9 are supported. Besides the main format MPEG-2 MP@ML, the formats MPEG-2 SP@ML {with reduced resolution) and MPEG-1 are both allowed. These formats are optimized for applications where storage quantity is more important than quality. For example, the MPEG-1 format allows 15 hours of video to be stored on a DVD-5. Audio formats Audio formats have been debated for a long time: whereas Dolby Digital (AC-3 compression) was chosen in NTSC countries (USA. Japan) at an early stage, MPEG-2 audio (not to be confused with MP3. MPEG-1. layer-lll) was favored in PAL countries (Europe. Australia, etc.). In the meantime both formats have become accepted in Europe. That simplifies the production process considerably and helps make distribution faster. Dolby Digital supports up to six channels (the sixth channel is assigned to the subwoofer so that it is usually written as 5.1) and MPEG-2 even up to eight (as 7.1 ). DVD players that do not support multichannel output only output the left and right channels as a standard stereo signal. Apart from compressed audio formats it is also permissible to store uncompressed PCM audio. Again, up to eight channels are supported and quality can even be significantly better than with a CD: up to 24 bit/96 kHz (the CD " only" supports 16 bit/44.1 kHz). Moreover, there are a number of optional formats (SDDS, DTS) which can, however, only be used in addition to one of the above formats. Therefore, at least one of the standard formats (Dolby Digital, MPEG-2 or PCM) must be available on a DVD video. In PAL countries all DVD players (and even the PC hardware which can play back DVD videos) must be able to process Dolby Digital, MPEG- 2 and PCM and output them at least as an analog signal. Only Dolby Digital and PCM must be supported in NTSC countries. Further information Besides the practical advantages (playback as often as required, small size) the attraction of DVD video is its interactive feature: for example, up to eight versions (e.g. languages) for audio and up to 32 subtitle tracks are supported. Likewise, videos can be subdivided into chapters and one out of up to nine camera positions can be selected without delay during playback. For different versions of a film it is possible to set jump marks at points in the film where the story is to be continued without delay. Naturally, information on authors, titles, etc. is stored. Two crucial functions are regional coding and copy protection. There are six regional codes that prevent playback of DVD videos with a certain code on players with a different code. For example, DVD videos from the USA cannot be played back on players in China. This copy protection is intended to prevent unallowed, digital copying of commercial DVDs. DVD authoring How does the required information get on to a DVD video? What is necessary for print-to-DVD? What data is essential and what data ", is optional? The process of DVD authoring (i.e. the creation of a DVD) still involves a great dear'of work and is thus cost-intensive. This is due partly to expensive encoders (to create MPEG-2 video data) and partly to the applications (authoring software) that are needed to create the program.