Copyright law [LWN.net]

Copyright law

Posted Nov 12, 2020 14:58 UTC (Thu) by geert (subscriber, #98403)
In reply to: Copyright law by rsidd
Parent article: The RIAA, GitHub, and youtube-dl

I thought the access controls on a DVD prevent the _playback_ of the DVD, not its copying?

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Copyright law

Posted Nov 12, 2020 16:28 UTC (Thu) by Wol (subscriber, #4433) [Link] (5 responses)

No :-(

They mess about with a lot of stuff, and commercial DVDs won't copy - I've tried.

Cheers,
Wol

Copyright law

Posted Nov 12, 2020 18:57 UTC (Thu) by nybble41 (subscriber, #55106) [Link] (4 responses)

It's not that the commercial DVDs are uncopyable so much as the blank, writable DVDs lack the specific storage region needed for the CSS keys. As such, you can't burn an encrypted DVD image to regular retail DVDs (such that the resulting DVD can be played back) regardless of where it came from—that includes not only copies of commercial discs but even ones you created yourself. The anti-copying measure isn't actually in the commercial discs but rather in the blanks. It doesn't prevent anyone from extracting a bit-for-bit image of an encrypted DVD, but that doesn't do you any good unless you have the industrial equipment necessary to produce discs with the CSS keys included.

DVD anti-copying measures

Posted Nov 15, 2020 4:41 UTC (Sun) by giraffedata (guest, #1954) [Link] (3 responses)

So that's what prevents making a physical copy, but what prevents you from making a usable copy of the content on a flash drive or whatever is the encryption. That's the technological measure you have to circumvent to make that kind of copy.

If the encryption just stopped you from playing the DVD, I don't think DMCA would have much to say about it.

What takes most people by surprise about DMCA is that if you circumvent the encryption just to play the DVD, not to copy it, you're still in violation of the DMCA, because you are circumventing a technological measure that also prevents copying.

DVD anti-copying measures

Posted Nov 15, 2020 6:12 UTC (Sun) by nybble41 (subscriber, #55106) [Link] (2 responses)

> …what prevents you from making a usable copy of the content on a flash drive or whatever is the encryption.

The encryption doesn't prevent you from making a copy of the (still encrypted) content of the DVD on a flash drive. It only prevents you from playing the video from that copy, since it would need to be decrypted first. The only official, licensed systems that can decrypt the DVD content for playback will not accept encrypted input from a flash drive, only from commercial DVDs, so having a bit-for-bit copy of an encrypted DVD on a flash drive doesn't help. Still, CSS would be more accurately classified as protection against unauthorized *playback* rather than unauthorized *copying*.

DVD anti-copying measures

Posted Nov 15, 2020 17:45 UTC (Sun) by giraffedata (guest, #1954) [Link] (1 responses)

I think I could make a case that the content protected by copyright is the movie, not the bits. A copy of encrypted bits that can't be played is not a copy of a movie, so encryption is a device that prevents copying.

Sometimes engineers, with their view inside the machine, have a rather different perspective on copyright law than authors and copiers.

DVD anti-copying measures

Posted Nov 15, 2020 18:25 UTC (Sun) by geert (subscriber, #98403) [Link]

So my dm-crypted hard drive does not contain any movies, as the RIA* cannot play them?
Well played ;-)