DVD Demystified

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Playback Incompatibilities
Chapter 7
The DVD-Video specification was put together like a patchwork quilt, with
different parts coming from dozens of different engineers speaking Japanese,
Dutch, and English. The books were assembled and produced in Japanese
and then translated into English. Engineers from a large number of companies
all over the world implemented the specs in player designs. It is no surprise,
therefore, that the DVD-Video feature set is incompletely or improperly
implemented in many players. Even then, many incompatibility problems
have resulted simply from laziness or carelessness. Many early DVD title
developers had to scale back their plans after discovering that their ingeniously
designed discs worked differently or not at all on different players.
For example, the DVD specification allows 999 chapters per title, but
some players cannot handle more than 511. Likewise, players are supposed
to support 999 program chains, but some early players balk at 244. Some
cannot handle full video data rates of 9.8 Mbps, whereas others cannot deal
with extra files in the root directory. The release of The Matrix in 1999
brought wide publicity to the general malady. Because The Matrix was the
first million-seller DVD, and because it was an unusually complex title
that also contained PC enhancements, more people than ever before had
problems playing the disc. Some problems were caused by authoring and
formatting errors on the disc, but most problems were caused by flaws in
a surprisingly high number of player models.
Taking the long view, The Matrix and other “problem discs” did the DVD
world a favor by exposing flaws in players that failed to properly play
discs authored according to the DVD specification. Although the backlash
to the studios, production houses, and InterActual (the company providing
the PCFriendly computer enhancement software) was painful, pushing
the envelope early ensured that DVD manufacturers are now more
responsible about making players that work right. It is better to deal with
these “growing pains” early on when there are only a few million players
than later when there are tens of millions.
The number of players that continue to have design flaws, even after
many iterations, is inexcusable because they fail on discs that have been
available for years. Some problems are caused by bugs in DVD authoring
software, but as authoring software programs mature, most of them incorporate
workarounds to avoid known errors and deficiencies in players. The
situation is slowly improving with each new release of players, but producers
who want their discs to work on their customers’ players must still
accommodate older models.