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