Having been a software developer for over 20 years, I have always been intrigued by the opportunities, DVD offers to content providers, as well as the number of compatibility issues arising from this versatile format. As a result I have written this article for the trade magazine “Replication News” on the subject. Here is a reprint, as it appears in this months issue of “Replication News” that you should be able to find at your newsstand - if they carry trades, that is.

Although DVD is a fantastic home video format, giving viewers a visual and sonic experience like never before, the format is unfortunately also reason for plenty of frustration and a lot of confusion. Much of that frustration is a result of compatibility problems that have plagued the format since its introduction and now, almost two-and-a-half years later, compatibility problems have yet to be eradicated even from the most current DVD releases.

Although the general explanation for this problem lies within the fact that DVD is a non-linear format that is much harder to create and control than linear media, such as videotapes, the actual problems themselves are manifold and altogether highly technical in nature. Let me try to make some of the most frequent issues more understandable. In order to do that, I hope you understand that I will have to simplify and abstract certain things.

I remember the first disc I encountered with compatibility issues was Polygram's Kalifornia, one of the company's first releases.
The disc simply refused to play at all on Toshiba players, and it gave us an idea what to expect in the future: DVDs that are not recognized by the player; discs that freeze the player during playback; releases that go completely out of sync; and DVDs that refuse to give users access to certain parts of the programming. In the meantime we have seen them all and one would think that after all this time, solutions are at hand.

Unfortunately things are not really that easy. With every new player generation, with every new model that comes to market, chances are, we are seeing a refresher of these problems, and the key lies within computer technologies themselves. Just as the PC that you use to write your correspondence, a DVD player is a highly sophisticated computer. So sophisticated in fact that it can put most home computers to shame. The "Windows" of these DVD players is their firmware, operating systems that are programmed by the manufacturers to make sure DVD players understand a basic programming language and execute the

second street." While the first one is a clear determination of a destination, the second one is clearly relative to your starting point. If the starting point is incorrect you will never end up at the address you intended to go to, which happens on some DVDs. The operating system of some DVD players is not able to interpret the command sequence correctly and as a result locks up the player, or makes it believe it's not even dealing with a DVD disc at all. A correction in the operating system, called a firmware upgrade, can fix that problem, and all of a sudden, the same player knows perfectly well how to find its way around town.

A large number of compatibility issues have also appeared since the introduction of dual layer discs. Due to the lack of sufficient test objects at the time, it was a little tested feature in many first and second generation players with the result that many DVD videos simply locked up the machine when it was time switch to the disc's second layer. Ever since it has actually become the most common of all compatibility problems across the entire DVD catalog. The problem is somewhat similar to the aforementioned one, but many additional factors come into play because the disc is in the midst of playing back audio, video and possibly subtitle streams that need to be kept in sync. Because of this increased number of variances, layer change glitches are much more common than any other compatibility problem. Once again, however, a firmware upgrade can fix literally all of these problems, and you would be surprised how many supposedly 'defective' discs that are returned to retailers can actually operate properly by replacing an EPROM inside the DVD player that refused to play it.

Usually problems like the ones described above are not necessarily problems in the software as you can see--although real bugs (errors in the software) can also be a reason. Most of the time it turns out to be an inconsistency within the implementation of the DVD standards in DVD players and the communication of the software with the player's firmware.
Sometimes these problems don't rear their ugly heads until the day a DVD comes along that makes use of a certain feature that chokes a particular player.

For the longest time, many features of the original DVD specifications had never been touched upon in the real world, because there was no application for them. Many of the DVD specifications were practically academic in nature by the time they were decided upon. Laid out in technical terms on paper, somehow implemented in DVD players--or not, for that matter.
No one initially noticed their inconsistencies with one another because there was no application to actually tax these features--until one day, a publisher pulls a DVD that uses exactly those anticipated features. All of a sudden, latent bugs become glaringly visible, which brings us to the "Matrix Syndrome."

Highly publicized, the problems surrounding The Matrix seem bigger than they are in actuality. Unfortunately the fact that the title sold in huge numbers naturally magnifies the proportions, simply because a much larger number of consumers is suddenly confronted with these problems. It's not that there are so many problems with the release, it just that there are suddenly so many people seeing the problem.

The disc is a very sophisticated attempt to utilize some features of the DVD specifications that have not been used a lot in mainstream titles. Certain highly interactive DVD-ROM features interacting with DVD-Video content, multi-angle content and a number of other elements suddenly utilized parts of the players' firmware that had been dormant for the longest time in most of them. As a result, bugs in the firmware became evident, and because this particular disc was suddenly put to test in practically every player model in the market, the problems got exposed like an avalanche. The good side of all this is that The Matrix has probably turned out to be one of the most important DVD releases ever. Because of its scale it was the wake-up call for many DVD producers and player manufacturers that they need to pay very close attention to what they're doing. As much of a paradox as it may seem, as such it has presumably done more for the industry than any other title before.

Although it may seem that most of these problems are lying within the DVD hardware, it would be unfair to have such a tainted view. DVD has also had its fair share of releases that simply had bugs in their software, which caused a number of problems, from non-standard "bootstraps" all the way to 'dirty' tricks and shortcuts in the authoring. Today, most authoring facilities have learned many approaches how to avoid problems from the get-go. Many work-arounds for player-specific issues are known and usually implemented in the latest releases.
Nonetheless, especially start-up facilities will have to go through this learning curve and until they have reached the same plateau, they will make their share of mistakes, until their procedures are internally standardized and market-proof.

One of the things we are certainly all aware of is that these compatibility issues have to go away soon, if DVD is to become a mass-market product. It may be presumed acceptable to PC users to deal with bugs in their software, as it is a trade-off of the

make products attractive to the masses they need to be reliable and easy to use. The same is true for DVD and these compatibility issues do quite some damage to DVD's image in the consumers' eyes. After all, who would want to buy into a new video format that may make buying title releases a gamble?

For that reason we have set up a special list of "Problem Discs" in the "Film Vault" section of my website DVD Review. It gives our readers the opportunity to see if there are any known and documented problems with certain discs before they buy it, and they can report problems in case they encounter some.

Another area with even more compatibility issues is the area of DVD-ROM and PC computers. It is an issue that is so extensive that I will have to touch upon it in a separate article.

With the current developments in the industry, many of DVD's slumbering features are finally put to use, and gradually they will reveal flawed implementations, both on the hardware and the software side. However, especially hardware manufacturers need to make sure that their products are always one step ahead of the content providers, and it is essential that firmware upgrades are done quickly, efficiently and comfortably. I have had too many readers complain that they had to send in their DVD player for upgrades, without interim replacement, only to receive them back many weeks later exhibiting the same problems. Maybe service centers can help or trained staff in stores that can replace EPROMS within minutes. The times are changing and the industry needs to adapt. Just like every PC store can install, replace and fix computer components these days, the consumer entertainment industry needs to make sure that their products are maintainable to consumers' satisfaction.

This article has originally been published in “Replication News” and is reprinted here by permission.

 January 6, 2000

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