ARccOS ?? Why does it foul up the software but not my set top box??

[anthrax79]

I figure this has been ask before, but after reading and searching I never found a good answer.

I don't understand how ARccOS can keep the RIPping software from working, but not mess up a STB or even a software DVD player. It just makes no sense to me.

How does a 6 or 7 year old STB know how to ignore the bad / blank pointers in the VOB and still give me a great picture. And if the STB can deal with it why can't the ripping software???

So color me clueless and a noobe and enlighten me please!

[mikiem]

Wellll... you're box is dumb. No offence, but most all are -- they just need to play the DVD. WIndows or Linux or Mac OS has to understand it if you ask for more then playback.

[jagabo]

ARccOS specifically looks for loopholes in the DVD spec that allow them to create errors that don't effect set-top DVD players but do effect software rippers.

[guns1inger]

The idea is based on deliberately putting corruption into files on the disk. They put this corruption into parts of the disc that your player won't have to read, which is fine because your player only looks at what it's told to (as Mikiem pointed out, your box is dumb).

When you rip a DVD, the software has to take everything to ensure that the disc is usuable, but chokes when it hits the corrupt parts. Rippers are now getting smart enough to understand that all is not as it seems.

[whitejremiah]

ARccOS specifically looks for loopholes in the DVD spec that allow them to create errors that don't effect set-top DVD players but do effect software rippers.

This is not entirely accurate, if you have rather keen eyes, you can notice the video jumping for a split second here and there...i did notice it, for example, on xxx: state of the union...i didn't take a stab at backing up a copy of it, so im not sure if this is actually fixed in a backup, i'd have to assume it would be though, since the copy protection is stripped from the disc in doing this....i'd have to guess that a dual layer backup in this case is actually BETTER than the original.

[TooLFooL]

your question is also related to another common misconception of copy protection. many people have experienced errors when ripping discs that play perfectly fine on the set-top. they swear it is some new form of encryption when in actuality it is a scratch on the disc. the player can 'fudge' it and keep playing where the ripper fails.

[handyguy]

It puts a small file on your dvd that plays in a continuous loop. This fools a lot of backup software.

[BSpielbauer]

I don't understand how ARccOS can keep the RIPping software from working, but not mess up a STB or even a software DVD player. It just makes no sense to me.

I am certainly not any sort of expert at the way these things work, but I can try to help you understand this, based on what I have read.

To begin: The newer forms of copy protection try to exploit a single fact: DVD players are designed so that they keep on going when they see any sort of an error. DVD ripping programs are designed so that they stop whenever they see any sort of an error.

First, as someone did mention above, the fact that a DVD will play on a player is not at all related to whether a piece of software can successfully rip it to a hard drive, or encode it. The objectives of the authors were quite different.

-Joe wants to design a DVD player (or even software that plays a DVD on a PC), and he is determined to ensure the player will let you view your DVD. Joe builds in all sorts of error correction. If a segment cannot be properly read from the source, Joe can design the player so it will read the frames next to the bad ones, and hopefully "jump" to the next one which is readable. Joe can even program his DVD player to check several nearby segments, and try to find the next one which will work. This is one reason why dirty DVDs and scratched DVDs and bad pressings often somehow manage to play on most people's home players. Joe designs his player to try ignore or recover from any scratches, or dings, or errors, or problems, or blemishes, or mistakes in programming on the actual DVD.

-Bill has a different objective. Bill sets out to design a software program that will transfer an entire DVD onto the hard drive of a PC. So, he tries to make certain that every bit and byte is copied, with very few modifications. Bill may want to try to remove some or all of the native copy protections, but he wishes to preserve the files, and the .Vobs, and the structure, and the individual frames, and the "cells." He also wants to preserve the various "tags" or commands which catalog those files. Bill also wishes to preserve the commands which are built into the structure that tell a player the sequence or order that these should all be played. Most of the better programmers of rippers went for a goal of 100% accuracy. They designed programs that would halt or choke or spit out an error message the instant they encountered a missing piece of data, or a missing bit, or a missing byte, or a missing VOB, or a missing cell, or a missing PGC, or a missing command. Bill's software might stop the instant it cannot read a single piece of information. This was initially considered a good thing, as users did not want to end up with an end result that was missing parts, or which choked up on a home DVD player that tried to "play PGC 1.300" only to find that "PGC 1.300" was not to be found.

This is why dirty discs, and damaged discs often cause a good ripper to fail, although the disc can play fine on most home DVD players.

Sony ARccOS and the Universal "jumping / running boy video" and the newer RipGuard copy protection all take advantage of this difference in design. They do it in slightly different ways.

One version includes video segments that are not "listed" in any of the accompanying files that are supposed to list all of the video. This is called "unreferenced material." It is stuff that is there, but no command ever tells the DVD player that it is there, and no command ever tells the DVD player to actually play the stuff. Some of the rippers fail because they are so strict they check any "stuff' to make sure it is also listed somewhere in a "tag" or a "catalog" or a "list." DVDs have a complex set of commands that refer to the material on them, and instruct the player what t do next. If that material is never mentioned in any of those instructions, watch out... The ripper might realize there is a problem, and stop working.

Then, in another version, this can be stuff which is deliberately corrupted data. Garbage. Garbage video. Or, video in a continuous loop. Or, just plain Gobbledygook. Some rippers can handle the fact that the material is not referenced in any way. But, those rippers cannot handle the fact that it is obvious garbage. It realizes it is not encoding real video. The files cannot truly be "read" as valid video, or normal video. So, those rippers might fail. They stop, they choke, and (in some cases) they spit out the same old error message that was designed years before these new protections hit the market. They tell you this is a "cyclic redundancy error" which usually means a dirty disc. Or, they tell you that the program has run out of memory. Or, they tell you that the program needs to close now, since it has experienced an unexpected error. Et cetera.

As a real world example, DVDDecrypter (with the default settings) was a very strict ripper. It would stop on the slightest anomaly.

A ripper that does not stop on the slightest anomaly or error is the newer freeware program "DVDFab Decrypter." It was designed specifically to circumvent some of the structure problems, specifically Sony ARccOS, and it was released right after DVDDecrypter was "shut down." It is excellent at ignoring problems with Sony ArCCos, generally. But, the downside of this is that a program like this might also ignore a dirty disc, or a scratched disc, and let you continue ripping stuff that will be flawed when you try to look at it later. Or, it might merely transer the "structure protection" right onto your hard drive so that when you later try to open it to re-author it, or to compress it, or to work on it or change it in any way, the "structure protection" still causes some other program to fail.

This issue gets even more complicated when we add "RipGuard" into the mix, which is just a new wrinkle on this same method. And, it also gets more complicated when one realizes that the protections are trying to be a sort of a "moving target," where last month's release used unreferenced video, but this month's release might use tags that refer to a video sequence that is not even on the disc, only to find a command following it that tells a player to jump over to a different sequence. Your DVD player has no problem, due to the "command after." A lot of rippers are confused, as they expect that the command to play cell 124559 should also mean that there is an actual cell 124559...

So, to repeat, in summary, I believe the following to be true: The three newer forms of copy protection try to exploit a single fact: DVD players are designed so that they keep on going when they see any sort of an error. DVD ripping programs are designed so that they stop whenever they see any sort of an error.

Again, I am NOT an expert, so if anyone cares to correct my errors, or to clear up my fuzzy thoughts, please, by all means, jump in.

-Bruce

[TooLFooL]

BSpielbauer pretty much summed it up!

[fritzi93]

A ripper that does not stop on the slightest anomaly or error is the newer freeware program "DVDFab Decrypter." It was designed specifically to circumvent some of the structure problems, specifically Sony ARccOS, and it was released right after DVDDecrypter was "shut down." It is excellent at ignoring problems with Sony ArCCos, generally. But, the downside of this is that a program like this might also ignore a dirty disc, or a scratched disc, and let you continue ripping stuff that will be flawed when you try to look at it later. Or, it might merely transer the "structure protection" right onto your hard drive so that when you later try to open it to re-author it, or to compress it, or to work on it or change it in any way, the "structure protection" still causes some other program to fail.

Yes, which is reason enough to not trust it entirely. And it needs frequent updating to cope with new dodges. Same with AnyDVD.

Look here:
https://forum.videohelp.com/viewtopic.php?p=1448399#1448399

and here:
https://forum.videohelp.com/viewtopic.php?p=1448499#1448499

[anthrax79]

Bruce,

Thank You!!. While you may not be an expert, your detailed descriptions are great. It makes sense now. Skipping bad data (ie scratches) makes sense for the STB. However I assumed that the STB's would be designed to follow the commands and so a bad TAG or Play Next command would send the player to that spot and cause an error. But now I understand that with the design philosophy being different, the STB would just ingore the error and find the next "good" command and keep on playing if possible.

Thanks again.
Matt