Re: Idea: The ultimate CD/DVD auditing tool
On Wed, 9 Jul 2003, Peter Fairbrother wrote: the nyquist/lindquist/someone-else-who-was-pissed sampling theorems are based on the possibility of mathematically extracting frequencies from digital information in a STEADY_STATE situation. That doesn't mean that a speaker will properly reproduce those frequencies. Nor does it mean the op amp driving the speakers will follow them either. High speed and power are a hard combination to build. Consider the dynamics of energy transfer. A digital signal at near-1/2-sampling frequency will have two datum points. The transitiion between them will be dramatic! the possibilities of energy transfer will not be comparable to an analogue sinusoidal waveform. And that's why good analogue is better then good digital. It's definitly why you need fast digital. To reproduce 20+ kHz you should use a 200kHz sample rate and have a nice filter stage before the power amp. good digital can do more things than good analog because the final output is good analog in both cases. The speaker driver is pure analog by definition. To produce 65kHz (for cats) my present boss prefers a 1 MHz sample rate. The guys who do bats think it's good enough for 200kHz, but my boss won't do bats - much too complex. We've got a 25 bit dac which updates at 1 MHz, but we still need a nice filter and analog output stage for 120 dB clean signals. (I'm only getting 100 dB because it costs too much to really do the best possible.) Clearly a digital system can be built that can create any wave form a speaker can follow, and it's easier to control than an analog system. The human hearing system is capable of noticing phase relations at 100kHz rates. So any sample rate faster than 200kHz is outside the range of human detection. Cats can notice phase shifts in the 200kHz range, and bats are out in the 400kHz range. Biological systems *are* impressive. But digital vs analog is a silly argument, the final stage is analog. Patience, persistence, truth, Dr. mike
Re: Idea: The ultimate CD/DVD auditing tool
At 07:15 PM 7/8/03 -0700, Mike Rosing wrote: To produce 65kHz (for cats) my present boss prefers a 1 MHz sample rate. Do cats buy a lot of audiophile equiptment :8=|| The human hearing system is capable of noticing phase relations at 100kHz rates. Actually I thought humans are insensitive to phase relations, modulo inter-aural timing at low frequencies for spatial location. Perhaps that is what you meant? But spatial location isn't the same as the frequency-fetishing audiophiles go for. To do that well you need casts of the outer ear too. You doing owl-type studies on auditory localization? Audio-visual mapping and plasticity? Making the cats wear funky glasses?
Re: Idea: The ultimate CD/DVD auditing tool
On Wed, 9 Jul 2003, Major Variola (ret) wrote: Do cats buy a lot of audiophile equiptment :8=|| Nope. That's why I have a job (for another couple of months anyway, till the grant runs out.) Actually I thought humans are insensitive to phase relations, modulo inter-aural timing at low frequencies for spatial location. Perhaps that is what you meant? But spatial location isn't the same as the frequency-fetishing audiophiles go for. To do that well you need casts of the outer ear too. No, if you put 2 clicks out that are 10 usec's apart on right and left, most people can pick out which side came first. 90% of the time anyway. You doing owl-type studies on auditory localization? Audio-visual mapping and plasticity? Making the cats wear funky glasses? Yup. they sew coils into their eyes. For humans they use contacts :-) PETA is definitly a problem :-) Patience, persistence, truth, Dr. mike
Re: Idea: The ultimate CD/DVD auditing tool
On 2003-07-08, Major Variola (ret) uttered to [EMAIL PROTECTED]: I haven't, but it does ring true. You'd get 2 Khz as well as other intermodulation products. Provided there's a nonlinearity, effective in the ultrasonic range, somewhere. Mere interference (which is what we usually refer to as beats) doesn't give rise to intermodulation. The beat, it isn't an audible frequency per se, but double the frequency you'd need to amplitude modulate a sinusoid halfway between the original sinusoids to get an equivalent result. You've read about the company trying to sell highly localized speakers? They modulate two intense ultrasound beams, and the air does the nonlinear mixing where they meet. You can do it with a single beam, too. MIT's Sonic Spotlight is one example, but there are better developed applications on the market. However, you need huge amplitudes to get the air to distort. (I've heard numbers in the 130-150dB range.) In the audiophile, lower-intensity case, the ears' nonlinearity would do it. I don't think it would. Before the nonlinearity gets to do its job, the sound needs to be conducted to the inner ear. But it probably won't be -- our ossicles and the tympanic membrane are too massive to operate in that frequency range. So I agree if the amplitudes are extreme, but otherwise I doubt it. -- Sampo Syreeni, aka decoy - mailto:[EMAIL PROTECTED], tel:+358-50-5756111 student/math+cs/helsinki university, http://www.iki.fi/~decoy/front openpgp: 050985C2/025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
Re: Idea: The ultimate CD/DVD auditing tool (meow)
At 11:45 AM 7/9/03 -0700, Mike Rosing wrote: On Wed, 9 Jul 2003, Major Variola (ret) wrote: Actually I thought humans are insensitive to phase relations, modulo inter-aural timing at low frequencies for spatial location. Perhaps that is what you meant? But spatial location isn't the same as the frequency-fetishing audiophiles go for. To do that well you need casts of the outer ear too. No, if you put 2 clicks out that are 10 usec's apart on right and left, most people can pick out which side came first. 90% of the time anyway. Yes this is for localization ---clicks are broadband, you need to identify which freq components are used. I still think humans can't discriminate the phase of a tone. In fact, MP3s use this to cut bits. You doing owl-type studies on auditory localization? Audio-visual mapping and plasticity? Making the cats wear funky glasses? Yup. they sew coils into their eyes. For humans they use contacts :-) PETA is definitly a problem :-) Gaak. I was thinking prism-glasses maybe bolted on that translate the vis field. Its ok for undergrads so its ok for cats. After the experiments, the cats will be ok, as I assume they're sufficiently plastic, unless you do brain staining on them. :-(Or your policy is the Tim McVeigh treatment. Cool stuff, though my domestic feline wants to know where you live. PS: have you identified the can opener sound brain-center yet? Cats manage biometrics and reputation better than most human systems..
Re: Idea: The ultimate CD/DVD auditing tool
On Tue, 8 Jul 2003, stuart wrote: Now, when DRM gets into windows, I'm sure Virtual Audio Cable will stop working, RealAudio will stop making linux clients (why bother?), RIAA will (try to) make CDs that can only be played with windows clients, etc. Then someone will crack the formats of the audio streams and the CDs, and round and round she goes, where she stops, nobody knows. As things are now, it's easy to get the digital signal before it reaches the DAC, you don't need to go to DAC - ADC, you don't need to plug your line-out to your line-in and degrade your signal. If the RIAA get their content to only work on Windows-type boxes, and if MS gets DRM to work in their Windows, things will become much more difficult. But these are big ifs that can quite possibly be circumvented even if they do come to fruition. There's always high-end sound cards that don't even use analog. DRM is not going to stop file sharing. They're trying to catch smoke with nets. Yup, check out this dvd unit: http://www.220-electronics.com/dvd/daewoo5800.htm where it says: Custom modification with code free automatic and manual selection of regions and macrovision disabled. Excellent quality dvd player with all the features. and Price just reduced by over $100. Was 249.00 Now only $129.00 The Daewoo 5800 custom modification has been designed to make life a lot less complicated. It has superb Audio and video components outperforming major brands such as Sony, Panasonic and Pioneer. So it won't be long before bypass systems will be commercially available. At least in some parts of the _free_ world. Patience, persistence, truth, Dr. mike
Re: Idea: The ultimate CD/DVD auditing tool
On Tuesday, July 8, 2003, at 10:40 AM, Peter Fairbrother wrote: A curiosity, only tenuously related - I just came across a Feb 1994 copy of Elector magazine, with plans for a S/PDIF copybit eliminator (for SCMS). Seems people have been defeating copy protection for a while.. I've owned an Audio Alchemy SCMS-stripper since 1991, when I bought my first DAT machine. It cost about $99, was about the size of a deck of cards, and stripped the SCMS bits out of the digital bitstream. A later DAT machine I bought, a Tascam portable pro deck, has the SCMS stripped by default. (It takes in digital signals and writes to the DAT with the SCMS code set to unlimited number of digital copies allowed.) Likewise, a professional CD writer I own (HHB) bypasses SCMS. (Not just allowing a digital copy to be made, but making the resulting CD-R copyable freely.) A friend of mine bought his DVD player on EBay: it bypasses all region coding (i.e., it makes all DVDs region-free). Region coding is a different issue, but part of the DRM universe. Until George W. Bush and the Carlyle Group start putting money into these things and thus discover that SCMS strippers are terrorist tools, such tools will likely continue to be available. Use a logic analyzer, go to jail. --Tim May He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you. -- Nietzsche
Re: Idea: The ultimate CD/DVD auditing tool
At 02:55 PM 7/8/03 -0400, Billy wrote: On Tue, Jul 08, 2003 at 01:26:46PM -0400, Trei, Peter wrote: While the ear can't hear above 22KHz, signal above that *can* effect the perceived sound, by heterodyne effects. For example, if you play a single tone of 28KHz, or a single tone of 30 KHz, you can't hear them. Play them together, however, and you *can* hear a beat frequency of 2KHz. Bullshit detector buzzing. Is this *really* true? Have you tried it? I haven't, but it does ring true. You'd get 2 Khz as well as other intermodulation products. Standard EE stuff. You've read about the company trying to sell highly localized speakers? They modulate two intense ultrasound beams, and the air does the nonlinear mixing where they meet. In the audiophile, lower-intensity case, the ears' nonlinearity would do it. Interesting info, Peter.
Re: Idea: The ultimate CD/DVD auditing tool
On Tue, Jul 08, 2003 at 03:52:54PM -0400, Trei, Peter wrote: Billy [SMTP:[EMAIL PROTECTED] wrote: Bullshit detector buzzing. Is this *really* true? Have you tried it? Not personally, but The Net holds all knowledge. ... http://www.bostonaes.org/archives/2003/Jan/ http://www.acoustics.org/press/133rd/2pea.html Very interesting.. Thanks!
Re: Idea: The ultimate CD/DVD auditing tool
Tyler Durden leaves the fight club and writes: Do you have a reference? I don't remember reading that SACD was encrypted. What I DO remember is that the reason there's no standard SACD or DVD-A digital interface is because the Industry wants that digital interface to be encrypted. The detailed technical specs are apparently secret, but an overview of the multi-layered SACD copy protection is at http://www.sacd.philips.com/b2b/downloads/content_protection.pdf. If you don't like PDFs, most of the same information is at http://www.disctronics.co.uk/technology/dvdaudio/dvdaud_sacd.htm. Alan Clueless writes: Furthermore, people have come to expect that they should be able to play whatever disc shaped media in their computer. At some point there will need to be a software based player. Both of the documents above specifically deny that software based players will be allowed. I get the impression that the decryption will always be done in hardware, and if a PC is ever able to play one of these gadgets, it will be a Palladium system or something similar that can be locked down. Steve Shear writes: If you believe the article Myths and Misconceptions about Hardware Hacking, http://www.cptwg.org/Assets/Presentations/ARDG/ARDGHardware_hack05-28-03.pdf , recently posted to the Content Protection Technical Working Group, access to affordable commercial technology for reverse engineering has given hardware hackers the upper hand. That's mostly about how hardware hackers can use modern chips and custom PC boards without spending more than a few hundred dollars. Fine, but it's a long way from that to being able to pull an algorithm and/or device key out of a chip which has been designed to make that difficult.
Re: Idea: The ultimate CD/DVD auditing tool
At 03:14 PM 7/8/03 -0700, Tim May wrote: As for hearing heterodyning in 28 KHz and 30 KHz signals, maybe. CD players have brickwall filters to of course block such frequencies. Some analog groove-based systems can have some kind of signal up there at those frequencies, but not much. Regular vinyl is (was) also recorded with all kinds of filters, too, including the lowpass ones. If you cut vinyl (or metal) through a signal chain that didn't impose the filtering, perhaps the ultrasonics would remain, which is perhaps the analogophiles claim. You would need a special vinyl cutter though. Some of the filtering imposed on vinyl was to not fry the cutter, or otherwise deal with its inertia. (BTW, I thought your Monster USB cable was a prank.. its not.. some folks just don't get digital..)
Re: Idea: The ultimate CD/DVD auditing tool
okay I'm a bit pissed now. actually i'm raging pissed! Wh!!! the nyquist/lindquist/someone-else-who-was-pissed sampling theorems are based on the possibility of mathematically extracting frequencies from digital information in a STEADY_STATE situation. That doesn't mean that a speaker will properly reproduce those frequencies. Consider the dynamics of energy transfer. A digital signal at near-1/2-sampling frequency will have two datum points. The transitiion between them will be dramatic! the possibilities of energy transfer will not be comparable to an analogue sinusoidal waveform. And that's why good analogue is better then good digital. Doug Self etc. did some work on ultra-fast analogue systems in the mid 90's, and designed some amps that were and are regarded as pretty good - but afaik he didn't get the theory right. YHHH!-- Peter Fairbrother
Re: Idea: The ultimate CD/DVD auditing tool
On Tuesday, July 8, 2003, at 04:09 PM, Major Variola (ret) wrote: At 03:14 PM 7/8/03 -0700, Tim May wrote: As for hearing heterodyning in 28 KHz and 30 KHz signals, maybe. CD players have brickwall filters to of course block such frequencies. Some analog groove-based systems can have some kind of signal up there at those frequencies, but not much. Regular vinyl is (was) also recorded with all kinds of filters, too, including the lowpass ones. If you cut vinyl (or metal) through a signal chain that didn't impose the filtering, perhaps the ultrasonics would remain, which is perhaps the analogophiles claim. You would need a special vinyl cutter though. Some of the filtering imposed on vinyl was to not fry the cutter, or otherwise deal with its inertia. (BTW, I thought your Monster USB cable was a prank.. its not.. some folks just don't get digital..) Yes, they are real. I perhaps should have inserted a this is not a joke, but I didn't think to. When I was the judge in the First Internet Witch Trial, one of the examples I used was how believing something doesn't make it so, despite what the believers think (though the psychological effects may be real). An example being some audiophile nonsense, such as the Tice Clock (which is/was also real...some people bought the snake oil about how an LED clock plugged in could soften the harshness of digital. With the Tice Clock, with the Monster USB cables, one can examine the effects on bit error rates, and even look at timing jitter (a claim some manufacturers of snake oil make). For any of us with a remotely scientific bent, seeing that the bitstream is unchanged, that the bit error rate is unchanged, is pretty convincing evidence that no matter what we _think_ we hear, especially in non-double blind listening tests, there simply _is_ no difference. And yet there are people who claim to hear differences between 5 dollar digital cables and thousand dollar digital cables, even when the bitstreams are identical. (And even if they are not, they are within the capture window of the next digital gadget, and hence are for all intents and purposes absolutely identical.) One might as well sell Monster Cable Power Cords for PCs, claiming they make the Pentium 4 perform more accurately. Actually, I'll bet the tweaks are already buying special power cords for their Athlon 2200+ homebrews. Most so-called high end tube amps do in fact sound different, perhaps better, perhaps not. This is of course because tubes are usually rich in odd-order harmonics. That $4000 Krell tube amp is actually _coloring_ the sound. So much for 20-bit DACs in the signal source: the amp is altering the sound at about the 6th or 8th or whatever most significant bit. Bob Carver and a few others have emulated the tube sound so well with DSPs that double-blind tests using audiophiles cannot tell the difference, and where the waveforms look identical.
Re: Idea: The ultimate CD/DVD auditing tool
On Tuesday, July 8, 2003, at 01:39 PM, Anonymous via the Cypherpunks Tonga Remailer wrote: As an audiophile (Krell+Levinson+Thiel gear at home), I definitely don't want to grab an analog signal. Doing that the signal is sure to retain characteristics of the extracting gear. But the vast majority of P2P kids won't care one iota that their file was analog for half a second. -TD I'll ditto that - my brother is an extremist audiophile - he writes reviews for the high-end stuff (google Mike Trei). Many (by no means all) top end audophiles prefer all-analog equipment, and direct-cut vinyl records (ie, the master disk was cut directly at the performance, without a magtape master). I've listened to some of this stuff, and it just blows digital away. What else do you expect, when any audiophile who denies that inaudible frequencies make the music warmer proves himself to be a philistine with ears of tin? Remember, it was the fashion and clothing EXPERTS who were the most insistent that the emperor's new clothes were absolutely marvelous. The harshness of a digital bitstream can be softened by operating LED clocks in the same room as the bitstream. The Tice Clock, for example, works by plugging in to any electrical socket in the room where the listener is located...of course, all that matters is that he _sees_ the Tice Clock plugged-in, and remembers that he paid $399 for this piece of wondrous technology, for the effect to work. That the bitstream as measured with a logic analyzer is unchanged with any of these digital enhancers is beside the point. Monster Cable, by the way, is doing a nice business selling Extra Special, Oxygen-Free Copper Shielded, Insulated with Rubber Hand-Rolled on the Thighs of Taiwanese Virgins cables for _USB_. Yep, for USB. Never mind that the bitstream either is there or it isn't...some people think they get superior data with special $80 cables. As for hearing heterodyning in 28 KHz and 30 KHz signals, maybe. CD players have brickwall filters to of course block such frequencies. Some analog groove-based systems can have some kind of signal up there at those frequencies, but not much. Very, very few microphones are rated at 22-25 KHz, so I have to wonder just where this signal is coming from. If not coming from actual musical instruments, and detected by the microphones, why bother? Sure, we may as well push the CD spec up to 24 KHz or so. That will probably even satisfy Neil Young. --Tim May
Re: Idea: The ultimate CD/DVD auditing tool
Thomas Shaddup writes: As a welcomed side effect, not only we'd get a device for circumvention of just about any contemporary (and possibly a good deal of the future ones) optical media protections This is only for the minimal forms of protection which are designed to work with existing CD/DVD players. If you look at the new audio formats like SACD, they use encrypted data. All your lasers won't do you any good unless you can pry a key (and the algorithm!) out of a consumer player, which won't be easy assuming it is in a tamper-resistant unit. And you can bet the industry won't make the mistake again of allowing software-based players, as they did with the DeCSS affair. In short, you're fighting yesterday's war. Try looking ahead a bit to see where the battlegrounds of the future will be contested.
Re: Idea: The ultimate CD/DVD auditing tool
At 02:33 AM 7/7/03 +0300, Sampo Syreeni wrote: On 2003-07-06, Major Variola (ret) uttered to [EMAIL PROTECTED]: There's a good reason why, viz: it would cost the drive developer to allow or export this flexibility. I'd guess either because of a) terminal stupidity or b) benefits to scale in making it sure people go with compatibility. As there probably have to be some limits to how stupid engineers capable of making things like writable CD's can be, I'd have to go with the second alternative. Frankly its obvious you haven't worked (or thought about the constraints) on a commercial product with a deadline / resource constraints or worked on something extremely cost sensitive like commodity drives/chipsets. Here, ponder this: why are there no oxygen sensor or manifold temperature or ignition-phase (etc) displays in ordinary cars? (Although there probably are in custom race cars) You know (much like the analog CD signal) they're being measured and used by the ECU. So, why not? Chew on that one for a while, grasshopper. Economics is applied physics.
Re: Idea: The ultimate CD/DVD auditing tool
At 04:13 AM 7/6/03 +0200, 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. This is a valid idea. You do have to get in there with delicate probes to read the amplified analog signal, its not available past the drive. The people who already do this are called test engineers for CD drive companies. Or the data-recovery techs for the NSA et al. I doubt that hardcore pirates bother, they may as well just do a single high quality ADC. That, as has been mentioned here before, is always the fatal flaw, even if you put the DAC in your DRM chip (and solve the resulting noise issues..) Yes, we know they have logic analyzers in Hong Kong --a Sony engineer when confronted with weaknesses in the design of a DRM box
Re: Idea: The ultimate CD/DVD auditing tool
On 2003-07-06, Thomas Shaddack uttered to cypherpunks: If we'd fill this idea with water, would it leak? Where? Why? It wouldn't leak, and I've never really understood why standard ATAPI drives don't allow access to the raw data. As you say, that sort of tool would have quite a number of applications besides piracy. For example, taking MP3 backups of my CD's, I already would have needed error concealment, a feature CD-ROM's do not implement when ripping audio. You can't implement that well without knowing where the error correction step failed, and that data isn't easily available. Also, I've always been fascinated by the fact that there's really no reason to follow the CD specs beyond 8/14 modulation other than compatibility. A writing drive capable of working at such a low level could be used to experiment with new encodings beyond what standard CD's can do -- say, substituting CIRC with RSBC and gaining some extra room on the disc, getting rid of the subchannels, a more intelligent coding of disc addresses... Breaking compatibility wouldn't be too useful, but it sure would be fun. Now you simply can't do it. -- Sampo Syreeni, aka decoy - mailto:[EMAIL PROTECTED], tel:+358-50-5756111 student/math+cs/helsinki university, http://www.iki.fi/~decoy/front openpgp: 050985C2/025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2
Re: Idea: The ultimate CD/DVD auditing tool
At 03:08 PM 7/6/03 +0300, Sampo Syreeni wrote: . A writing drive capable of working at such a low level could be used to experiment with new encodings beyond what standard CD's can do -- say, substituting CIRC with RSBC and gaining some extra room on the disc, getting rid of the subchannels, a more intelligent coding of disc addresses... Breaking compatibility wouldn't be too useful, but it sure would be fun. And think of the ulcers you would cause the TLAs! Assuming they got your disks and not your custom drive... Now you simply can't do it. There's a good reason why, viz: it would cost the drive developer to allow or export this flexibility. Since very few customers are sick enough :-) to want to invent their own incompatible formats it simply isn't worth their development-engineering time or end-product resources (eg gates) in such a commodity product.
Re: Idea: The ultimate CD/DVD auditing tool
There's a good reason why, viz: it would cost the drive developer to allow or export this flexibility. Since very few customers are sick enough This will go the same way as radio. First, you have hundreds of separate boxes, each doing some custom modulation/frequency gig (am, fm, shortwave, TV, cell, spread spectrum, whatever) and you had to have a separate apparatus for each instance. With software radio, you just have one box that can do it all (and it made all protection-by-custom-modulation obsolete ... I've seen it playing protected HDTV signals.) So it's easy to imagine universal software disc player/recorder that let's one do any modulation technique. Not that it would provide protection, because the same tools will be available to attackers, but at least the crypto may become more fun, going back to physical domain. = end (of original message) Y-a*h*o-o (yes, they scan for this) spam follows: __ Do you Yahoo!? SBC Yahoo! DSL - Now only $29.95 per month! http://sbc.yahoo.com
Idea: The ultimate CD/DVD auditing tool
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. 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. We can push the idea a step further, making a stripped-down CD/DVD drive that would be able basically just to follow the spiral track with its head in constant linear velocity (easier to analyze than CAV) mode, with the ability to control the speed in accordance with how fast (and expensive) ADC, bus, and disks we have, and the possibility to interrupt/resume scanning anytimes in accordance with how much disk space we have (or to scan just a small area of the disc). As a welcomed side effect, not only we'd get a device for circumvention of just about any contemporary (and possibly a good deal of the future ones) optical media protections, but we would also get a powerful tool for retrieving data from even very grossly damaged discs, for audit of behavior of CD/DVD writers and CD vendors (eg, if they don't attempt to sneak in something like a hidden serial number of the writer), and for access to all areas of the discs - including the eventual ones unreachable through the drive's own firmware. If we'd fill this idea with water, would it leak? Where? Why?
Re: Idea: The ultimate CD/DVD auditing tool
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
