Adding macrovision style copy protection to a theora video

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Adding macrovision style copy protection to a theora video

Mark Toman
Is there a way to get a video output by ffmpeg to send an extra vblank with
random pixels that a TV would ignore but would mess up a video recorded on
a vcr? I am planning to develop come develop a video game and some of the
video cut scenes should not be possible to copy.
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Re: Adding macrovision style copy protection to a theora video

Carl Eugen Hoyos-2


> Am 19.10.2019 um 02:12 schrieb Mark Toman <[hidden email]>:
>
> Is there a way to get a video output by ffmpeg to send an extra vblank with
> random pixels that a TV would ignore but would mess up a video recorded on
> a vcr?

This describes a change on an analog video signal.
FFmpeg knows nothing about analog signal, it only handles digital multimedia (where no vblank exists).

Carl Eugen
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Re: Adding macrovision style copy protection to a theora video

Carl Zwanzig
In reply to this post by Mark Toman
On 10/18/2019 5:12 PM, Mark Toman wrote:
> Is there a way to get a video output by ffmpeg to send an extra vblank with
> random pixels that a TV would ignore but would mess up a video recorded on
> a vcr? I am planning to develop come develop a video game and some of the
> video cut scenes should not be possible to copy.

(There is/was a digital Macrovision, but as Carl Eugen mentions, MV really
an analog mechanism.)

First question is whether there will be an analog signal -to- record.
Assuming a PC/MAC-based game, the video signal is most likely digital or
RGBVH (VGA) and neither is convenient to record on a VCR or DVD recorder.

Likewise, if someone is using a screen recorder on the gaming machine, AFAIK
nothing will prevent the user from recording it that way.

And, of course, nothing will stop a user from aiming their camera at the screen.

Later,

z!
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Re: Adding macrovision style copy protection to a theora video

Bouke / VideoToolShed
On 19 Oct 2019, at 15:28, Carl Zwanzig <[hidden email]> wrote:
>
> And, of course, nothing will stop a user from aiming their camera at the screen.


This says it all.
(I don’t like +1)

Bouke
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Re: Adding macrovision style copy protection to a theora video

Marc Roos

Why not develop some watermarking technology? For audio you have even
some technique that can survive (some) re-encoding. And then have with
your users a license agreement. You can also just tell them you are
using this technology, while you do not ;)



-----Original Message-----
From: Bouke / VideoToolShed [mailto:[hidden email]]
Sent: zaterdag 19 oktober 2019 15:37
To: FFmpeg user questions
Subject: Re: [FFmpeg-user] Adding macrovision style copy protection to a
theora video

On 19 Oct 2019, at 15:28, Carl Zwanzig <[hidden email]> wrote:
>
> And, of course, nothing will stop a user from aiming their camera at
the screen.


This says it all.
(I don’t like +1)

Bouke
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Re: Adding macrovision style copy protection to a theora video

Carl Zwanzig
On 10/19/2019 11:04 AM, Marc Roos wrote:
> Why not develop some watermarking technology? For audio you have even
> some technique that can survive (some) re-encoding. And then have with
> your users a license agreement.

Those don't *prevent* recording, they only carry evidence of the source
(which may be acceptable).

Please don't top-post on this mailing list (any search engine will explain
what that is).

Later,

z!

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Re: Adding macrovision style copy protection to a theora video

Marc Roos
 

Nothing prevents recording. I thought that was already clear?


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Re: Adding macrovision style copy protection to a theora video

kumowoon1025
In reply to this post by Marc Roos
> On Oct 19, 2019, at 2:04 PM, Marc Roos <[hidden email]> wrote:
>
>
> Why not develop some watermarking technology? For audio you have even
> some technique that can survive (some) re-encoding. And then have with
> your users a license agreement. You can also just tell them you are
> using this technology, while you do not ;)

Speaking of licensing, where do copy protection features or producing copy protected content using GPL’ed software stand in the legalese? Just curious...

I wanna say though, I feel like how copy protection mechanisms usually work is, the more invested the content producers are in implementing it, the more likely it is to be defeated. Like MPAA level studios and their distributors are really into all the DRM and copy prevention schemes, and you see, not bootlegged, but pirated versions online all the time, with all the colorimetry info, HDR metadata, I mean that 4K HDR10 Atmos .torrent is not some analog hole capture, it’s the original source with its expensive DRM chopped off!

Sometimes, as long as content has the right balance of obscurity and a tricky enough copy protection to defeat, it’ll stay “protected”. So basically if your product becomes a successful commercially (a favorable situation) and the protection mechanism becomes defeated (now an eventuality) it’s like, why would you try to put the effort into something that’s only useful If your product is a failure you know?

But back to the op’s question, I do know it’s possible to include program metadata that _signals_ to the decoder that copy protection should be generated in any analog signals it outputs. But it can also ignore it and not do the extra work implementing clock sensitive analog signal processing (read: mangling), and to the user, since it can play more content, it’s not hard to see how it became de facto standard practice.

But a while back Vista Media Center up and refused to record some network’s shows one day (I think it was a Comcast one not sure tho), because Microsoft had implemented that particular feature, which is a real thing that nobody really did..? Especially for software? Then it turned out MS didn’t mean to do that, they just must have been really following the specs to the letter. Then the network said oh yeah that metadata flag we must have enabled it on that stream by accident sorry. But this was a rare exception. It pretty much shows almost no player respects this metadata (since other cablecard boxes had no problem) and content providers don’t even include it unless by mistake (since it known not to be very effective).

If you haven’t, read up on HDCP, which I’d say is the modern, digital data analogy to MV I think, It’s history is pretty impressive for all the wrong reasons, as it was pretty much a complete failure as DRM. HDCP actually encrypts the video in transmission with respectably sized keys, but how it negotiated how devices exchanged key data was revealed to be flawed in its design. Now the master key is out in the open. That’s like, not something even fee-paying content participants with executed licensing contracts had access to. To top it all off, it's the frequent cause of compatible sinks and sources not working claiming the other device is incompliant.

I’ve been rambling for a while now, but actually I think yeah it’s probably possible to insert metadata that signals copy protection using ffmpeg into a program stream. What I’m pretty sure of is that it can’t generate one on its own. Something else to consider, for this to work, the media decoder in the console(?) needs to be able to see that and insert the vblank pulses. And whatever media your game is distributed on is only compatible with a device that implements the copy protection mechanism. Basically you need control of the whole ecosystem, something like the NES comes to mind, what exactly is your distribution method?

> Is there a way to get a video output by ffmpeg to send an extra vblank with
> random pixels that a TV would ignoreicense agreement. You can also just tell them you are
> using this technolbut would mess up a video recorded on
> a vcr?
In other words, what is between the “video output” and “ffmpeg”? Obviously it’s not ffmpeg -> video output, or is it some hardware device that actually makes this possible?


Ted
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