Idea: The ultimate CD/DVD auditing tool

[Tim May]

On Saturday, July 5, 2003, at 07:13  PM, Thomas Shaddack wrote:

> Pondering. Vast majority of the CD/DVD "protection" methods is based on
> various deviations from the standards, or more accurately, how such
> deviations are (or aren't) handled by the drive firmware.
>
> However, we can sidestep the firmware.
>
> The drive contains the moving part with the head assembly. There is an
> important output signal there: the raw analog signal bounced from the
> disk and amplified.
>
> We can tap it and connect it to a highspeed digital oscilloscope card. 
> And
> sample obscene amount of data from it. In comparison with fast-enough
> ADCs, disk space is cheap. The problem can be in bandwidth, but for the
> drive speed set up to possible minimum (or for "normal" players) the
> contemporary machines should be sufficient. Real-time operating system
> (maybe RTOS-Linux) may be necessary.

No RTOS/Linux is needed for fast sampling, which has been happening for 
several decades now.  Nor is a digital oscilloscope needed.

(FWIW, I used a Nicolet digital oscilloscope, and also a LeCroy CAMAC 
digitizer, for some high-speed single-shot event capture--the strike of 
an alpha particle--nearly 25 years ago. The OS for our data collection 
computers were, variously, RSX-11M and VMS.)

Video ADC cards are already vastly capable at sampling video streams.

>
> We get the record of the signal captured from the drive's head - raw, 
> with
> everything - dirt, drop-outs, sector headers, ECC bits. The low-level
> format is fairly well documented; now we have to postprocess the 
> signal.
> Conversion from analog to digital data and then from the CD 
> representation
> to 8-bit-per-byte should be fairly straightforward (at least for 
> someone
> skilled with digital signal processing). Now we can identify the
> individual sectors on the disc and extract them to a disc image file 
> that
> we can handle later by normal means.

So? Yes, this is all possible. Any moderately well-equipped lab can do 
this. So?

>
> If we'd fill this idea with water, would it leak? Where? Why?
>

I have no idea what you mean by "fill this idea with water," but by all 
means go ahead and rig up such a machine.

Personally, I already make about 1-2 recordable DVDs per day, on 
average, without any hint of copy protection or Macrovision. I usually 
use the 3-hour speed on my DVD recorder, and can put one high-quality 
movie on the first part and then, by using a slightly slower speed, 
another movie on the remaining part. If "DVD quality" is needed, I 
record at the 2-hour setting. If "better than DVD quality" is needed, 
as from a DV camcorder source, I record at the 1-hour speed.

If you build a machine which has even higher digitization rates, taken 
ahead of any DVD spec circuitry, you will get about what I am getting 
at the 1-hour setting.

A very limited market for consumers to buy such machines. Video pirate 
labs very probably already have such rigs set up.

--Tim May
"Extremism in the pursuit of liberty is no vice."--Barry Goldwater