Popular HD DVD Disc Hits a Snag

An anonymous reader writes "Following weeks of headlines touting strong sales for Blu-ray discs, rival next-gen format HD DVD looked like it had its own success story in the making with this week's HD DVD release of the cult hit 'Children of Men.' The disc recieved a stellar review at High-Def Digest, and went on to out-sell the most popular Blu-ray discs on Amazon. But now comes word of apparent incompatibility issues with the Xbox 360 HD DVD player, with some (but not all) consumers reporting that even multiple returns of the disc are unplayable on the format's leading playback device."

Comments

What's old is new again

[Anonymous Coward]

A lot of 1st and 2nd generation DVD players had occasional trouble with some DVD titles. Given the complexity of something like DVD, HD-DVD or BluRay it's really to be expected. Both the hardware and software is complex enough, and many Slashdoters know the difficulty of getting both new hardware and software to work together properly.

Re:What's old is new again

[Half a dent]

My first DVD player refused to play The Matrix properly when it was released (quite common at the time). IIRC this was due to an interactive feature (follow the White Rabbit?) not being compatible with the firmware version of the player, looks like a similar story here.

Re:What's old is new again

[EtherMonkey]

Given the complexity of something like DVD, HD-DVD or BluRay it's really to be expected.

So, in other words, it's ok for me to pay $400 for a new, standards-certified, HD-DVD player and then $30.00 each for HD-DVD-labeled movies, but I shouldn't expect them to work together? And because I've probably owned the HD-DVD player for several weeks/months before coming to this sad realization, and because I obviously need to open the shrink wrap on the HD-DVD movie before attempting to play it, I cannot recover any of the money I've paid for this premium, standards-organization-certified, combination of player and media?

Well, at least now that I own the physical media and therefore have legal license to play the movie, I can legally download a working, albeit lower-quality copy off the Internet. Oh wait, that's still illegal.

Eventually, all the crap that the entertainment companies go through to implement copy protection, (a.k.a. DRM), is going to wind up frustrating even the most steadfast consumers of legally-aquired recordings, and they will be driven to pirate downloads as a matter of survival.

Re:Less issues with HD-DVD then Blu-ray

[flynt]

I have had issues with Crank and Speed.

There are clinics to help you with that.

Re:Why can't the industry make things compatible?

[illegalcortex]

Is there really a difference in the error correcting codes written to +R and -R?

Yes.
From http://adterrasperaspera.com/blog/2006/10/30/how-t o-choose-cddvd-archival-media/

As I said earlier, DVD-R sucks for data preservation for three reasons: inferior error correction, inferior 'wobble' tracking, and the fact its data writing methods look like an un-needed halfway point between CD-R and DVD+R. The wobble tracking I shall explain first, then the error corrections method, then the specifics of ATIP/pre-pit/ADIP optimum power settings.

For a CD/DVD burner to track where it is on the disc, it uses three things: the 'wobble' of the data track (where it actually wobbles back and forth instead of in a straight line) to tell where it is in the track, the position of the track to tell where it is on the disc, and some additional information on the disc to tell where the track (singular, as CDs and DVDs only have one track, and it is written in a concentric spiral) begins and ends.

This additional information on a CD-R is called the ATIP (Absolute Time In Pregroove), which contains how long the track is, where it begins, what the maximum and minimum writing speeds are, what formula dye it uses, who actually made it, optimum power control settings, and error correction data. The ATIP is stored as a frequency modulation in the wobble itself.

However, since the wobble changes subtly to encode data, it is impossible to use with the small size of tracks DVD requires, as electric noise in the laser pickup and wobbles introduced by the electric motor spinning the disc, these could easily be read as frequency changes in the real track itself.

On DVD-R, they tried to solve the problem with something called 'pre-pits' where spikes in the amplitude of the wobble appear due to pits fully out of phase with the rest of the track (ie, between two spirals of the track, where there is no data). This can be viewed as a simple improvement over CD-R as it makes it easier to track the wobble (since the wobble is constant except for the easy to detect and remove spikes).

Unfortunately, this method as one flaw: due to electric noise in the laser pickup, it would be very easy to miss the pre-pit (or read one that wasn't actually there) if the disc were damaged or spun at fast speeds. The time to read a pre-pit is 1T (roughly .0000000038th of a second), which even for a computer can be easy to miss. DVD-R traded hard to track frequency changes for hard to read wobble-encoded data.

On a DVD+R, however, they came up with a much better method. Instead of changing the frequency of the wobble, or causing amplitude spikes in the wobble, they use complete phase changes. Where CD-R's and DVD-R's methods make you choose between either easy wobble tracking or easy ATIP reading, DVD+R's method makes it very easy to track the wobble, and also very easy to encode data into the wobble. DVD+R's method is called ADIP (ADdress In Pre-groove), which uses a phase change method.

With ADIPs' phase changes, the direction of the wobble changes and continues on going in the exact opposite direction (ie, counter-clockwise to clockwise, or the reverse). For example, if the wobble was 'going up', the phase change causes it to instantly reverse direction start 'going down' no matter where it in the wobble cycle. The phase change is very easy to detect, and also continues for a set period (in this case, one 32T section of the track, or 32 times longer than the pre-pit method of DVD-R).

The state of the phase change (clockwise or counter-clockwise) encodes the individual bits in each block In essence, with the phase change method, not only do you have an easy way of tracking the wobble, but you now have an easy way of reading wobble-encoded data.

As I mentioned earlier, this wobble-encoded data includes error correction of wobble-en