How can people so easily assume that the watermark was truly the only tracking present? HBO wouldn't immediately come out swinging even if they knew who or where the copy was leaked.
Game of Thrones leak and watermark: a stupid tracking system
11–20 of 286 posts
Re: Game of Thrones leak and watermark: a stupid tracking system
#12How do we know they're not using techniques like this?
Re: Game of Thrones leak and watermark: a stupid tracking system
#13Not very clever. Get two leaked copies, and mix them up. Use the credits from copy A, or hell, even chop off 11 milliseconds from them. Then mix and match scenes... even chop off a few ms from some randomly selected scenes. I bet you wouldn't even need the two copies.
This assumes you know the method they are using. As the post mentioned, a few milliseconds + or - at the end of a scene would not be noticeable and the overall timestamp would still be constant if "self-compensating offsets" were used.
Re: Game of Thrones leak and watermark: a stupid tracking system
#14While using the millisecond length of things would be clever and would catch which copy it originated from while it remained secret that was how you were doing it. As soon as it was known it is not much harder for the person ripping the copy to shorten all the scenes by a random number of milliseconds than it is for them to blur the watermark.
I mean this could be a good addition to the current tech used in something like Cinavia, which is the most robust system I have seen and if not already doing it could easily identify individual sources. But the inaudible audio and steganography used in that system just seem much more of a pain to circumvent than using lengths of scenes as a serial number of sorts.
Re: Game of Thrones leak and watermark: a stupid tracking system
#15It's a bit hard to encode millisecond scale differences in scene or credit lengths - when the video is quantized to ~40ms frames...
Re: Game of Thrones leak and watermark: a stupid tracking system
#16...or just use steganography. Steganography in videos can be made to be invisible to the naked eye, and extremely robust - even to video compression. It's also difficult to detect, and even more difficult to remove/tamper with. What the author of the article is proposing is actually a kind of steganography, albeit a rather crude one, and probably rather difficult to implement (since scene timings will be different fo…
Of course we have no idea if they used steganography or not, right? He bases the article on the idea that they have no tracking info except the watermark, but I don't see any evidence that they don't know more.
To be honest, when I heard that the files were protected with a watermark, I assumed that they actually meant a steganographic watermark. I thought that this tech had been adopted into the industry ages ago, I'm rather surprised if it isn't the case, given the arms-race between the media and illegal distribution.
Re: Game of Thrones leak and watermark: a stupid tracking system
#17...or just use steganography. Steganography in videos can be made to be invisible to the naked eye, and extremely robust - even to video compression. It's also difficult to detect, and even more difficult to remove/tamper with. What the author of the article is proposing is actually a kind of steganography, albeit a rather crude one, and probably rather difficult to implement (since scene timings will be different fo…
It it were a full-screen steganograph it would need to be subtle as to not interfere with viewing. So could that be combatted by re-compressing with another codec?
Re: Game of Thrones leak and watermark: a stupid tracking system
#18Not very clever. Get two leaked copies, and mix them up. Use the credits from copy A, or hell, even chop off 11 milliseconds from them. Then mix and match scenes... even chop off a few ms from some randomly selected scenes. I bet you wouldn't even need the two copies.
This assumes you know the method they are using. As the post mentioned, a few milliseconds + or - at the end of a scene would not be noticeable and the overall timestamp would still be constant if "self-compensating offsets" were used.
You can figure out the method they are using by comparing two copies.
Re: Game of Thrones leak and watermark: a stupid tracking system
#19While this is cool idea, how possible would it be to extend any particular scene by that short of a time? If the video is output at a typical 24 fps, the shortest any scene could be modified would be ~42 ms. Even with a lot of newer footage being filmed at 48 fps, it's still only able to clipped at a rate of 21 ms.
Past that, I've seen a small amount of time shifting take place during a not-so-careful re-encode. At 1 ms precision, even this would be enough to throw off such a tracking system.
Re: Game of Thrones leak and watermark: a stupid tracking system
#20Not very clever. Get two leaked copies, and mix them up. Use the credits from copy A, or hell, even chop off 11 milliseconds from them. Then mix and match scenes... even chop off a few ms from some randomly selected scenes. I bet you wouldn't even need the two copies.
Only if you knew that was already going on. Security by obscurity, but still, I don't believe this kind of watermarking was ever used.
Maybe something like Cinavia[1] could be used instead? It's an analog watermarking system for detecting pirated copies and refusing to play them if player detects such copy is played on something else than bluray disc. Apparently this survives transcoding, and was/is major pain for people ripping their discs for various reasons and trying to play the files on certified players.