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Another Audio Watermark Scheme Wins TI DSP Contest
CaptainTylor writes: "Texas Instruments' DSP and Analog Design Contest Challenge is over, and the winner is a group of students from Technion, the Israel Institute of Technology, who presented yet another scheme for digital-audio watermarking, and got US$100,000 for it. Here is a Dallas Morning News article on the winners, which is of course light on the tech details. Abstracts of the winner and the other two finalists are available, but I couldn't find the full submissions. It's worth noting that the competition was not specifically about copyright protection, just about using the TI TMS320 DSP in interesting ways. Wonder how long it'll take before someone cracks this scheme..."
And speaking of schemes, cracking, audio and contests, Logic Bomb writes: "According to an article from the Associated Press, the United States National Archives are holding a contest of sorts to see if anyone can finally figure out what was erased on the infamous Watergate tape that pushed Nixon's downfall over the brink. It would be amazing to have this national mystery put to rest."
try burning a SafeDisc2 protected image on a new Plextor drive.
No problem. The PlexWriter PX-W2410A does perfect Safedisc 2 copies, at least with the firmware shipped to reviewers.
Of course, SD2 is pretty much broken if you take into consideration BetaBlocker, a program you can use to 'fix' a SD2-protected image prior to burning. Works with any burner.
Belief is the currency of delusion.
All digital watermarking does is represent digital data (actually, any type of data, but in this case it they say digital) in an analog form, which is then grafted onto a larger source (the most common example being a music file).
So, just like a modem signal, a water mark is digital data that has been turned into sound. It has to be fairly robust to withstand degradation of the original signal yet still be readable. To be effective as a watermark (in music) it also has to be unobtrusive, i.e. you don't notice it. But it is an audio signal that (if you want it to be effective for things like SDMI) resides within the range of human hearing, or more accurately within the range of common recording devices.
(Very) Simple example: I spell my name in Morse code with a dog whistle that has a frequency just above what the human can hear but within the range of common recording equipment (be they digital or analog) while recording "Push Push in the Bush." I have now crudely watermarked that track.
Now, I can't hear the watermark on the recording that I made, and I make copies of this track I still won't be able to hear the watermark (because it is still just slightly above the audible range of humans, although my dog may howl), but its still being passed on from copy to copy.
If I serially copy it from tape to tape to MP3 and back to tape, assuming that there wasn't too much signal degradation (and if there was the music would sound like shit too) if I played that 4th generation copy and fed the signal through an oscilloscope, you'd still be able to see the Morse code, and my dog will still howl.
Now, how does this thwart copying and protect copyrights? It doesn't. That's not the point. All a watermark does is merely encode data into an analog system that will stay intact from analog copy to analog copy assuming the signal hasn't degraded to much (and like I said a good, robust watermark should be able to withstand a fair bit of degradation). Where the copy protection comes in is that the SMDI folks want to make devices that will recognize a watermark in an audio file and allow or not allow it to be played.
Check out:
.F. Tilik, A.A. Beex. "Encoding a hidden digital signature onto an audio signal using psychoacustic masking", in Proc. 1996 7th International Conf. on Signal Processing Apps and Tech.. pp 476-480
for a much better explanation.
If you don't have anything nice to say, say it often.
- Ed the Sock
Well, I'm just an armchair engineer, but since you don't have a reply right now I'll chime in.
The answer is, as always, yes and no.
For the codecs and such, yes. You could make a programmable player and as long as you had enough cycles you could make it able to decode anything with downloaded firmware. For new media types, like CD-R vs. DVD you would need new hardware too. The optics for CD don't work on DVDs. But the DVD optics can read CDs.. so you can go backwards just like everything else in computers today. So what this gives you is a modular player unit that can accept various drive types for media, and has a programmable DSP to run the decoders on. So you could download a Ogg Vorbis decoder for your player that used to do MP3 only, for example. But you would have to buy hardware to be able to play CDs instead of just flash cards or whatever it was able to do before.
Yes, it would give customers a lot of freedom. But it would probably cost a little more and be a little bulkier. And eaiser to break since you have peices that have to be able to come apart. Would it sell? To geeks, sure, you could make a few bucks. To joe user? Hmmm... don't know. Some would like it I'm sure. Put it in a really cool case with pretty colors as an option and you might get somewhere. If a big name like Sony built and marketed it, even better chance.
but, the piracy that they're trying to fight wouldn't normally be created with analog equipment...the recording industry realises that people have been taping stuff from the radio or cd/tape to tape for years, the fact that it's so easy to create CD or nearly CD quality recordings with cheap equipment seems to have them running scared...
how about mp3 compression, would the compression destroy a simple hide-it-in-the-highs type of watermark, or are there ways to get around it?
if the signal does remain in the audible range, the only ways I can see of injecting a message without altering the original song would be playing "tricks" with amplitude or duration...both of which would be totally useless for digital-analog recordings and would probably send epileptic or tell every tenth kid that "it's time to kill"......hmmmmm, maybe they've just modified the old subliminal message tricks? hehehe...be prepared to buy every crappy record that comes out.
Their presentation to the judges was very impressive (we presented first, and all I could think while watching theirs was "we're screwed..."). They demonstrated both the addition and detection of a watermark for pre-recorded and live audio. A couple of times, they played out loud just the watermark. It was pretty garbled, but you could definitely make out the content of the original audio. They did it for both vocal and instrumental music; both times, you could make out the lyrics and melody of the original sound. And when combined with the original, the watermark was inaudible (as promised).
But the most impressive part of all is that it was all done in real-time. They watermarked the audio from a local radio station as it was being broadcast, playing both the resulting watermark and watermarked audio with virtually no delay.
I told them in Dallas, but I'll say it again- Congratulations on winning. You guys were definitely worthy competition. With any luck, we'll face each other again next time around.
-patrick
It's been done..every CDR/CD/DVD/DVDRAM maker makes their own firmware..most of the components are generic off the self stuff..the problem lies in that you have to "reverse engineer" the PCB layout etc, and figure out how to program the micro-controller on the board..some companies go one up, and produce a custom ASIC...and well all know what reverse engineering gets you under the DCMA and EULAs..even for our OWN HARDWARE.
Lets be clear here....... these watermarks are in the AUDIO - not in the specific digial representation. They are designed to survive thru generation loss, going from digital->analog->digital again (and maybe going form CD -> MP3 encoding back to CD) or any of a thousand variations.
If i make a recording that is a voice saying "DO NOT DUPLICATE" and every recording device on the market 'listens' for that sound, and if it hears it refused to record, the fact that you play via analog an re-record won't matter. The only way around it would be to remove the "DO NOT DUPLICATE". Now what these schemes do is exactly that - except they do lots of complicated and tricky ways to hide "DO NOT DUPLICATE", along with trying to encode it in the most robust fashion even if the signal gets modified. And in the same vein, they try to hide the signal in such a way that removing it would cause too much undesireable in the underlying music. The Stanford guys that broke the SDMI challege showed that it was possible to remove, but removing it ISN'T simple.
In your above 'cracking' example, it would only work if your recording device (not the microphones, the actual machine that persisted the music coming in) didn't respect/obey the watermark.
You haven't cracked anything. You've only demonstrated that you haven't a clue on how this technology works, nor a simple basic understanding of signal processing theory. If you ask Santa nicely he might bring you a spectrum analyzer for chrismas.....