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At 05:59 PM 2/22/00 +1100, Ian Farquhar wrote:
[much deleted, discussing a new Intel gadget for preventing
pirating of video streams]
>I am also forced to note that this won't stop physical
>duplication, eg. by photographing the screen. Anyone
>familiar with real-world piracy will know that many (if not
>most) bootleg video tapes and Video-CD's of recently
>released movies are produced by video taping a screen. This
>won't affect that, and the market for those piracies seems
>insensitive to the quality loss.
I am curious: Are there better techniques for getting
high-quality images out, rather than just videotaping a
screen? If I am given a sealed box with a CRT, is there
some technique I can do to get a better copy of what's being
sent to the screen? It seems like it should be possible to
read small parts of the screen very closely, perhaps
detecting the power of the electron beam that's painting the
image on each position and color. It's reaonable to do this
over only a small area of the screen at a time. Imagine an
8'' x 10'' screen displaying a rented movie or other
``copy-proof'' video stream. That's 80 square inches, so if
we could only scan in one square inch at a time, we'd just
have to play the movie 80 times. We might take multiple
samples from each square inch and do some kind of averaging
to smooth out quantization errors, noise in the system, etc.
I think all copy-protection runs into a wall when it gets to
human-perceptible output, at least in dealing with
determined pirates. Though the Intel scheme probably does a
good job of preventing cheap, casual copying of video
streams, which is presumably their purpose for doing the
design in the first place.
> Ian.
>Disclaimer: personal opinion only.
(Me, too.)
- --John Kelsey, kelsey (at) counterpane (dot) com
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