FC: Hollywood wants to plug "analog hole," regulate A-D

[Joseph Ashwood]

Everything I'm about to say should be taken purely as an analytical
discussion of possible solutions in light of the possibilities for the
future. For various reasons I discourage performing the analyzed alterations
to any electronic device, it will damage certain parts of the functionality
of the device, and may cause varying amounts of physical, psychological,
monetary and legal damages to a wide variety of things.

There seems to be a rather siginficant point that is being missed by a large
portion of this conversation.

The MPAA has not asked that all ADCs be forced to comply, only that those in
a position to be used for video/audio be controlled by a cop-chip. While the
initial concept for this is certainly to bloat the ADC to include the
watermark detection on chip, there are alternatives, and at least one that
is much simpler to create, as well as more benficial for most involved
(although not for the MPAA). Since I'm writing this in text I cannot supply
a wonderful diagram, but I will attempt anyway. The idea looks somewhat like
this:

analog source ------>ADC------>CopGate----->digital

Where the ADC is the same ADC that many of us have seen in undergrad
electrical engineering, or any suitable replacement. The CopGate is the new
part, and will not be normally as much of a commodity as the ADC. The
purpose of the CopGate is to search for watermarks, and if found, disable
the bus that the information is flowing across, this bus disabling is again
something that is commonly seen in undergrad EE courses, the complexity is
in the watermark detection itself.

The simplest design for the copgate looks somewhat like this (again bad
diagram):

in----|---------------buffergates----out
        ----CopChip-----|

Where the buffer gates are simply standard buffer gates.

This overall design is beneficial for the manufacturer because the ADC does
not require redesign, and may already include the buffergates. In the event
that the buffer needs to be offchip the gate design is well understood and
commodity parts are already available that are suitable. For the consumer
there are two advantages to this design; 1) the device will be cheaper, 2)
the CopChip can be disabled easily. In fact disabling the CopChip can be
done by simply removing the chip itself, and tying the output bit to either
PWR or GND. As an added bonus for manufacturing this leaves only a very
small deviation in the production lines for inside and outside the US. This
seems to be a reasonable way to design to fit the requirements, without
allowing for software disablement (since it is purely hardware).
            Joe