The minimum difference in scene length allowable would be a single frame.
I wouldn't be surprised if MP4 (or other video formats) provided a mechanism for tweaking the timing of a given frame. Of course, if you're using such a primitive watermark you might as well just add a note in the metadata...
You know how annoying it is when you watch a movie and there's some sort of 2-dimensional 'hacker' character and s/he just says some gobbledegook about 'hacking the password' or whatever, you see something a progress bar briefly on screen, and then the actor says 'we're in!' In short, how stupid movies can be about computer topics? Well that's how it feels when someone who knows nothing about video formats or editing comes up with suggestions about adjusting the length between scenes by a few milliseconds and having it slightly different for every viewer.
It's where you read a page full of comments about something you really and truly deep know something about and see how very, every wrong nearly everyone is...
...then you go on to take every other page pretty seriously without remembering just how far off people were on the topic that you know about. I experienced this the other day when people were talking about beep.js on HN.
(xhe) http://www.goodreads.com/quotes/65213-briefly-stated-the-gel...
Thanks. Now I know the name for this.
Here's an example of a deliverables manual, from Netflix: http://newworlddistro.com/wp-content/uploads/2013/10/FullTec... You will get something similar from any broadcaster or video distributor. I'm not making careless extrapolations of my knowledge here, but telling you what the industry standards are. I have long involved email conversations about these things with distributors so that stuff I submit to them doesn't get sent back, triggering contractual penalty clauses for late/non-delivery that will make a producer cross with me.
"Huh, this frame is supposed to be delayed by 3ms. Ah, screw it, [checks 'force to 23.97 fps' button]."
not to mention how you would go about defining the ends of scenes...
no standard format that i am aware of has variable framerate. it makes no sense.
Watermarking is a deterrent to the people who upload the content in the first place. The ones who're careless about who they'll share things with. A unique watermark (steganographic or visible) is about finding the source of the leak. In that arms-race the entertainment industry is facing people who can remove a watermark - but we have no idea whether or not they're winning. The fact that torrents exist with watermarks intact makes me think that perhaps they are.
I would have gladly paid them to watch a stream at 8pm last night, yet somehow that still isn't an option in 2015.
Instead I ended up with 4 episodes from a torrent at 8:15. Tell me more about embracing new technology as it comes to market.
HBO Now is Apple TV exclusive for 3 months.
I googled around for about 15 minutes and was only able to find news articles announcing it. I'd be happy to pay them for what i've already watched if anyone could direct me to a sign-up for this elusive streaming service.
I don't have an iOS device or their specific supported ISP, so I haven't signed up.
The visible fingerprint might just have been there to deter the clueless. In any case even with a fingerprint its hard to proof without a doubt, the individual who actually stole it.
I don't think they need to prove that a certain individual stole it. The party which received the advanced copies likely had to take on liability, so HBO can go after them. Of course, that doesn't mean they won't turn around and lean on the actual culprit, but whether or not they catch someone HBO will have their due.
I've heard of minor reviewers and third party firms getting cut off after a leak is traced to them, but for the most part the back office people simply don't have the power to enforce against anyone of note. Also the evidence just isn't enough for an actual law suit against someone who can hire a lawyer.
1: http://torrentfreak.com/super-8-screener-leaks-with-howard-s...
In short, don't try to film a movie in a theater; they will find you.
The author jumped to the conclusion that those don't exist, apparently because they aren't visible (but that's the point!) and that there is a visible watermark which the author apparently assumed was the only one (but it almost certainly isn't).
Given a known frame, they could blur the same portion of the same frame on all watermarked copies, and the one with a matching output is your culprit.
Blurring loses information, but is more akin to a hash than a deletion, as it's a deterministic process.
Edit: this sort of thing. http://dheera.net/projects/blur
You can if you have the original file, but then what's the point?
Otherwise, take image a=original+f1, image b=original+f2. Then if you e.g. average them you still have c=original+f1/2+f2/2 -- so both signatures are kept (theoretically if either you have a large number of sources you could average the signals out of existence, or perhaps the system isn't robust and can't detect multiple sigs). This assumes the introduced signatures are indistinguishable from the source (quite reasonable).
...but easy to explain (and sell?) to the entertainment industry, who have shown themselves to be mostly technically illiterate. Some cynical, unscrupulous hacker could probably extract a lot of money from them for such a service...
You can also embed data in the audio channel by alternating between two imperceptible echo kernels for 1/0[2]. This is extremely compression resistant.
1: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumb...
2: http://www.slidefinder.net/a/audio_steganography_echo_data_h...
Lossy compression: discard all sub-threshold information.
Thus, in the general case it's fundamentally impossible. You can make a scheme that will survive certain known encoders and bitrates, but you can't make one that will survive all lossy compression.
Split & merge frame by frame, in random, from multiple video sources. Visually they will be the same, but steganography has a high chance of been broken.
Disclaimer: I used to work at one of the leading companies in this field.
Could you link to some papers? If you try to encode lots and lots of messages with different keys into the video, does it ruin the quality before ruining previous messages?
impressive!
Sometimes, it's not about the money.
Pre-release screeners often have big ugly on-screen watermarks. Almost anything is better than a scrolling mid-screen line of text "PROPERTY OF STUDIO NAME DO NOT PIRATE THIS FILM".
Anyway, the horses have bolted and the damage is done.
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 for each episode, and you'll need to keep a separate log of exactly which timings correspond to each person you've distributed the file to), compared to running a video through a process that embeds a steganographically hidden id pattern at each keyframe.