Everything You Wanted To Know About DVD-R And More.

This article is the second in a two-part series. The first part appeared in the February issue of CTR.

Incremental writing is also supported by the DVD-R format. This is very similar in concept to the packet writing technology that is used with CD-R. Incremental writing allows a user to add files directly to a DVD-R disc one recording at a time instead of requiring that all files be accumulated on a hard disk prior to writing as with the disc-at-once method. The minimum recording size must be at least 32KB, (even if the file to be recorded is smaller), as this is the minimum Error Correction Code (ECC) block size for DVD.

A disc that is being written incrementally cannot be considered a complete volume until the final information has been stored or the disc capacity has been reached. The lead-in and lead-out boundary areas, therefore, cannot be written until either of these two events occur. Such an "unfinalized" disc (one without lead-in, lead-out, and complete file system data) can only be read by a DVD-R drive until this process can be completed. After finalization, a destination playback device can, then, read a disc, but data can no longer be added to it.

Recording Platform

Pioneer has made successful recordings onto DVD-R discs using a host computer system comprised of the following components:

* Pentium 100Mhz PC or better

* Windows NT 4.0 or Windows 95/98 operating systems (software dependent)

* Premastering application software

* Adaptec 2940 SCSI host adapter 

* 9GB hard drive

* External SCSI-2 DVD-R drive

This configuration represents a modestly powerful computer system containing no exotic components and should be relatively easy for a typical user to assemble.

Time To Record One Disc Side

A complete 3.95GB side is written in approximately 50 minutes in a disc-at-once recording, regardless of the data that will be contained. A 4.7GB disc can be fully written in approximately one hour. Even variable bit rate MPEG video data is recorded at the full 11.08Mbps rate. Upon playback, a video player accomplishes the necessary bit rate variation with a buffering technique. All information, video or otherwise, is written at the full 11.08Mbps data rate (or faster depending on the drive specifications) with playback equipment providing any necessary time base adjustments.

DVD-R Applications

DVD-R's relatively low cost per megabyte physical storage efficiency and easy portability of its recording equipment make the medium applicable to a large variety of uses in virtually all industries. There are three fundamental applications for DVD-R:

* Testing and development

* Distribution

* Storage and archival

Testing And Development

Many DVD applications utilize replicated read-only discs that are mass-produced and distributed to a large number of users. Preparation of the content that will be published can be a complex and time consuming process that must be completed accurately to avoid errors or functional defects. Compared to the cost of the mastering and set-up efforts required to replicate only one disc, DVD-R provides a far more cost effective method of testing content prior to mass production. A single low cost disc can be quickly written and tested in a representative destination device (video player or ROM drive).

In fact, multiple test discs may be required throughout the development process, as published titles are often the collaborative effort of many people. As a result, DVD-R media can make a significant contribution to reducing the cost of DVD publishing.

The relatively recent achievement of 4.7GB capacity on DVD-R media has helped to realize parity with DVD-5 replicated discs. This allows both qualitative and functional testing of titles that will utilize the full capacity of mass-produced media--a substantial issue in the DVD video authoring world.

Distribution

The key attributes of relatively low cost and playback compatibility allows DVD-R to be effectively used for small-scale distribution of DVD content. As in the testing example above, mastering and replication expenses can be prohibitive when only a single disc or very small quantity is required. DVD-R allows discs to be recorded at the desktop level, which can result in very quick turnaround and significantly lower cost.

Some users may not be comfortable with sending sensitive data files or other work in progress to an outside facility for replication, so the ability to maintain continuous inhouse control of this information can be crucial. This is particularly true with classified data maintained by government agencies. Complete confidentiality can be accomplished through the use of DVD-R because it can easily be maintained as a completely in-house process.

Storage And Archival

DVD-R media provides an archival life expectancy that is equal to or better than CD-R; for this reason, the format is suitable for long-term archival of any information that can be stored digitally. This includes image data, film and video archives, or any other media that need to be retrieved more easily by users. In fact, DVD-R's much larger capacity makes it especially suitable for large image files that do not fit onto a single CD-R volume, thus creating new opportunities for inexpensive storage of these assets. High-resolution satellite images are an example of very large files in excess of 1GB each.

Since DVD discs are dimensionally identical to the CD family of discs, they have the advantage of being compatible with existing CD-based jukebox and changer mechanisms. This allows automated retrieval of recorded DVD-R volumes in networked environments with a six to seven-fold increase in storage density as compared with CD-R technology.

As an example of how DVD-R can reduce overall archival system costs, a 100-disc DVD-ROM jukebox can contain a total of 470GB or nearly a half-terabyte of data. If 50KB image files are written on every disc, a total of ten million images can be stored and retrieved in a single, compact device. Using CD-R, seven of the same jukebox mechanisms would be required to maintain the same disc-to-drive ratio, which significantly adds to the system cost.

In essence, DVD-R dics can be thought of as enormous "bit buckets." Any kind of digital data can be stored on them such as high quality video databases, motion pictures, document images, audio recordings, multimedia titles, and so on. The format's high capacity and data transfer rate has the potential to expand existing CD-R applications in two dimensions: faster information flow (i.e., higher quality video), as well as significantly more data on each volume.

DVD Recordable provides users with a powerful new tool that has applications in nearly every industry. DVD-R is the next logical step forward from the very successful CD-R format in applications that benefit from write-once security, but inevitably require more capacity. As DVD technology takes its place as the eventual replacement for the ubiquitous CD, DVD-R will become an indispensable medium that can be counted upon to store and deliver digital information reliably and inexpensively.

Andy Parsons is the senior vice president of product development and technical support at Pioneer New Media Technologies (Long Beach, CA).