DVD Demystified

64
Chapter 2
Express, a company that planned to release Divx, a “DVD rental” format, in
the summer of 1998. Furious controversy burst out, with backers hailing it
as an innovative approach to video rental with cheap discs you could get
almost anywhere and keep for later viewings and detractors spurning it as
an insidious evil scheme for greedy studios to control what you see in your
own living room (Table 2.2). Of course, most of the detractors already owned
DVD players and were annoyed that they could not play Divx discs on them.
Contrary to many claims, Divx was not a competing format—it was a
pay-per-viewing-period variation of DVD. The discs were designed to be
purchased from any retail outlet at a price close to rental fees. The $4.50
purchase price covered the first viewing. Once inserted into a “Divxenhanced”
DVD player, the disc would play normally for the next 48 hours,
allowing the viewer to pause, rewind, and even put in another disc before
finishing the first disc. Once the 48 hours were up, the “owner” of the disc
could pay $3.25 to unlock it for another 48 hours. Divx DVD players, which
initially cost about $100 more than a regular player but later dropped to a
premium of only $50, included a built-in modem so that they could call a
toll-free number during the night to upload billing information. Since the
player only called once a month or so, it did not have to be hooked permanently
to a phone line. There was a DivxSilver program that allowed most
discs to be converted to unlimited play for an additional fee of $20 or so. The
idea was to let buyers purchase a disc at low cost, try it out, and then pay
full price if they liked it enough to watch repeatedly. Unlimited-playback
DivxGold discs were announced but never shipped.
Divx players were able to play regular DVD discs, but Divx discs were
designed not to play in standard DVD players. Each Divx disc was serialized
with a bar code in the standard burst cutting area so that it could be
uniquely identified and tracked by the player for billing and encryption
purposes. In addition to normal CSS copy protection, Divx discs used modified
channel modulation (making normal drives physically incapable of
reading protected data from the disc), triple DES encryption (three 56-bit
keys), and watermarking of the video. Ironically, the company had nothing
to fear from pirates who made bit-for-bit copies, since copied discs would
still require authorization and billing. A pirate outfit would simply be providing
free Divx replication services. Actual cracking of the encryption for
copying video to standard DVD discs was a potential threat, but Divx technicians
claim that no one ever got through even the first layer of protection.
Limited trials of Divx players began June 8, 1998, in San Francisco and
Richmond. The only available player was from Zenith (which at the time
was in Chapter 11 bankruptcy), and the promised 150 movies had dwindled
to 14. The limited nationwide rollout (with one Zenith player model and 150
movies in 190 stores) began on September 25, 1998. By the end of 1998,