[mythtv-users] Time Warner & Firewire

Mark Knecht markknecht at gmail.com
Wed May 18 16:07:07 UTC 2005


On 5/18/05, Lane Schwartz <dowobeha at gmail.com> wrote:
> On 5/17/05, Brad Templeton <brad+myth at templetons.com> wrote:
> 
> > DRM requires a system where the default is no copying and only certain
> > exceptions are allowed.  That precludes open tools and open source.  It's
> > hard to imagine any DRM, even the most permissive, not shutting linux
> > tools out of the media playing space.   I have imagined some methods but
> > they remain ugly and still shut out the innovation that this space is
> > about.
> 
> Brad, given the non-trivial technical hurdles that preclude open
> solutions from competing in many aspects of the HD arena (not to
> mention DMCA legal obstacles), perhaps we should look to our legal
> options.
> 
> Do you think that a company (which sells Myth boxes) or group of
> developers could bring suit against either the cable/satellite
> companies on anti-trust grounds? The Myth-based company claiming that
> they are being excluded from the HD PVR market, perhaps.
> 
> Are there other legal avenues that we could pursue?
> 
> Lane

Lane,
   Before we run off to court let's understand a bit more here. MythTV
is not in any way precluded by the 5C spec from being a remote device
that uses encrypted HD content and displaying it on a video screen.
What 5C says is that the encrypted content cannot be decrypted and
sent around a system to be stored and manipulated in it's unencrypted
state. This is no different for Linux, Mac or Windows platforms.

   The 'proper' way (as per 5C) to handle this in the system is to use
a video display device (probably an AGP VGA card, but it could be a
TV) that has the built in 5C decoding in hardware. That way the data
remains protected until it's put on the screen. Myth TV might be
recording the encrypted data stream  for playback at a later time on
it's own PC hardware or a 5C enabled TV. Even within that TV is was
made purposely hard for anyone to get the perfect digital copy, but no
more difficult than it would be to have it in a PC. All technologies
were treated in a more or less equivalent manner. (TTBOMK)

   Any PC is allowed to participate in 5C key exchange and become a
receiving device on the 1394 bus as long as it follows that part of
the spec. That part of the spec, as I remember it, did not discuss how
the data is encrypted as it wasn't important for that part of the
system. Do the key exchange protocol correctly and you can get the
data from the HD set top box or HD-DVD player. If another device does
it correctly with you then you are allowed to send it on to them.

   I think the *problem* here is that we're all used to thinking about
manipulating raw data from non-HD sources while clearly the HD content
providers are not interested in anyone doing that to their content. 5C
sets down a set of technology rules for what can happen and where it
can happen. It's really just a mind set change to start moving away
from the idea of transcoding TV shows and toward a system where you do
not touch the data but can still use it for personal viewing. However
Linux (as a technology) is no more restricted from participation in
using these data streams than Windows.

- Mark


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