An Introduction to the DVD

 

Originally called Digital Video Disc, then Digital Versatile Disc, now simply DVD, the medium offers massive storage in a number of formats. Some, such as DVD-Audio, are likely to be of increasing interest in time, but for our purposes, we consider only DVD-Video. That is the form in which we find increasing numbers of operas, many at reasonable cost.

 

Saying that a DVD offers massive storage prompts the question: How much will fit? Unfortunately, the answer is a bit complicated. A DVD may have multiple 'layers' and may be recorded on both sides. Since one layer on one side typically holds about two hours of material, the capacity is eight hours per disc with a single interruption to change side. However, since using both sides means that the publisher cannot put art on the top, that choice is rarely used. A second disc is inexpensive, so two-sided DVDs are rare. Few publishers choose to use multiple layers, again preferring to provide two single-sided, single-layer discs in the package.

 

Many of the features of DVD-Video (hereinafter, just DVD) are intended for films and are of little interest for most opera recordings. For example, DVD can have multiple sound tracks, offering a film in several languages with a single flow of images on the screen. Obviously, each 'sound track' for an opera would be a different work - Carmen in Italian is not the same opera that it is in the original French.

 

DVD is already replacing both tape and LaserDisc (LD) for opera and film recordings. There are many advantages to the DVD format including lower cost of production and higher potential quality of video and audio. Just as significantly, both DVD and LD allow selection by chapter; when chapters are well identified that capability can be of great value. DVD is always more convenient, usually less costly, and most importantly longer playing than LD. No longer must one change side or disc every hour or less; now most operas and any opera act will fit onto a single side of a single disc allowing enjoyment as one would in the house - an act without interruption. Finally, one of DVD's options can be of substantial value: selectable subtitling.

 

Both LDs and tapes had subtitles 'burned in'; one had no choice of subtitling (language or none) for a given release. (Theoretically, subtitles could have been provided as closed captions, but few can use them and that solution was rarely chosen if ever.) DVDs may have subtitles in many languages if the producer has source material without them and chooses to supply them. The Dreamlife Le nozze di Figaro is subtitled in English, Italian and Japanese - and most valuable to many of us, they may be turned off altogether. Unfortunately, some publishers either begin with titles burned in or do not create subtitles at all. In those cases, the situation is similar to that of LD and tape.

 

DVDs are encoded in several ways, discussed at length. It is essential that you know the capabilities of your system to handle that encoding and the properties of a disc you are considering. If your player can handle only Region 0 and 1, then you will not be able to watch a Region 2 disc.

 

One note of concern: DVDs permit an introductory segment with credits, copyright notices and other material at the choice of the publisher. In some cases, they may include extended previews, often of unrelated material; in others, they may be at excessive volume levels or otherwise disturbing to comfortable viewing. Unfortunately, that segment cannot be skipped and must be tolerated each time the disc is played even if one wishes to access only one chapter.

 

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Technical Notes

 

Encoding and encryption, or why the DVD won't play

 

In defining the specification of DVD, several sorts of restriction were built in. The video format is an issue common to all media, though today in practice it is reduced to PAL and NTSC. The strongest encryption used, called CSS, is relevant only for digital extraction of the DVD content so is not considered here. Playback may be encoded with Macrovision to restrict analogue duplication and each disc carries a 'region' designation for licensing and marketing purposes.

 

It must be noted that publishers do not consistently specify region coding on their packages and retailers are frequently careless about providing the information to the consumer. On Opera Japonica pages, we specify the publisher and region of the reviewed DVD.

 

NTSC/PAL

 

The video signal one sees on a monitor is formed from RGB on the DVD. The components include luminance, chrominance and synchronization. The NTSC coding generally used in north and central America, Japan and some other areas differs from that used in the rest of the world in the way the signals are presented to the display.

 

As a result, a monitor designed for PAL only will not display an NTSC signal and vice versa. Fortunately, all quality monitors designed for PAL today also support NTSC; unfortunately, few NTSC displays will handle PAL. Conversion from PAL to NTSC may be effected in an external device or in some DVD players. An external converter typically costs more than the DVD player itself, so if an NTSC user anticipates using PAL discs, she should ensure that the player will effect the conversion.

 

Macrovision

 

Macrovision is a process trademarked by a company of the same name. In theory, it allows viewing of the program without interference but causes an analogue copy to be disrupted and essentially un-viewable. Two levels of Macrovision are supported for DVD. The lesser one is a more powerful version of that known from VHS; it can be defeated with some external devices and is not effective on some older recorders. In addition, some older monitors may be affected by Macrovision encoding. The symptom of a problem with first-level Macrovision is video which pulses from normal brightness to extremely dark. A second level of Macrovision is available to the producer at higher cost; at this time of writing, very few discs use that level and no defeat mechanism is documented. Note that Macrovision is implemented in the playback electronics based on information encoded on the disc. Unlike a VHS tape, a DVD has no encoding in the video signal itself.

 

Regions

 

Six geographic regions were originally defined with region 0 for worldwide. One for in-flight movies was added later.

 

Regional Codes:

 

0: Worldwide

1: Canada, USA, US Territories

2: Japan, Europe, South Africa, Middle East (including Egypt)

3: Southeast Asia, East Asia (including Hong Kong)

4: Australia, New Zealand, Pacific Islands, Central America, Mexico, South America, Caribbean

5: Former Soviet Union, Indian Subcontinent, Africa

6: China

7: Reserved

8: Special (airplanes, cruise ships etc.)

 

With regional coding, a title may be released in one area independently of the others. That allows a distributor to cover only part of the globe and allows the producer to keep a film off the DVD market while it is still playing in theatres there.

 

Like Macrovision coding, regional coding is implemented in the player. The DVD announces its region and the drive electronics determine whether it may be viewed. Some computer (DVD-ROM) drives permit changing the region setting a specific number of times. In general, consumer machines are committed to the region in which they are sold.

 

Opera DVDs are more likely to have global scope and to be region 0 than films, but you still should check before purchasing that the product is playable in your region, i.e. that it is identified as being coded for your region or as region 0. Because the same title may have content particular to that region (e.g. subtitle and menu languages, supplementary features, PAL or NTSC coding), information about the DVD sold for one region may not apply to those sold for others.

 

Are there code-free, region-free DVD players?

 

To be complete and fair, one must note that there are code-free (no Macrovision) and region-free (all-region) DVD players occasionally offered for sale. They are rarely produced in that form but may be modified by the seller. As a result, they will have only the seller's warranty and their sale may be technically in violation of law. In some cases, information on making a specific player region-free or code-free may be readily available on the Internet for the purchaser to modify it himself. Again, the legal implications are unclear and surely vary among nations. A strict reading of the United States Digital Millennium Copyright Act states that any attempt to defeat a manufacturer's encoding and any publication of a mechanism for that purpose would be illegal.

 

Michael Richter, 8 July 2002

mrichter@cpl.net

 

For a list of reviews see the DVD Project page.