[mythtv-users] HD input in the future (DVI and HDMI)

[Alex]

> I had read a source that suggested you could not get a licence for the
> HDMI stuff if you didn't promise to do HDCP, but I haven't verified that.

What would be the point of doing HDMI without HDCP?  HDMI is really
geared towards the consumer electronics market.  I have yet to see a
DVI/HDMI source in this market which didn't support HDCP.  All the
current receivers support it too.

Just because the transmitter and receiver support HDCP, one does not
have to use it unless the content provided requires that level of
protection.

> Today if you made an STB that did only HDCP, there would be many problems
> because of people who can't use it.  That, they plan to change.

This assumes that a STB would always enable HDCP.  Perhaps they do. 
However it would be possible for instance for an ATSC tuner to only
enable HDCP when the broadcast flag is set.   It would depend on the
content.

The point of HDCP is to make the content providers comfortable enough
to enable these devices to play it.

> They are currently less concerned about component video because it adds
> A2D to the problem of recording it, and today that's expensive.  But
> when it gets cheaper the goal is to marginalize that as well.

HDCP is specific to TMDS signalling, however it could be applied to
other digital forms.  The analog signal is protected by CGMS-A and
Macrovision depending on the situation.

> > Also note that there's been a lot of suggestion that HDCP is quite readily
> > crackable, quite possibly already effectively cracked; there's just not yet
> > a good motivation to distribute the cracks ala libdvdcss, since nobody
> > could yet do anything useful with the unencrypted DVI stream anyhow.

HDCP can be cracked by defeating the transmitter such that it does not
turn on encryption or by having a set of valid keys...

> They have developed whole new rafts of key revocation tech that, in theory,
> let them revoke only the solo device that was compromised.   

Yep - that's one of the intents of HDCP.  It is quite technically
feasible as each device has a unique value.  However as the previous
mail alluded to, it may never be put into much practice.  Discovery
and management of a list of compromised key sets is not trivial.

> With the long term goal of putting the decryption at the very last stage
> before display (ie. cablecard etc.) we'll probably see this sort of
> technique.

HDCP could very well have decyption (and re-encryption) at any stage. 
If you plugged your HDMI player into a HDMI aware AV receiver, it can
decypted the stream, decode the audio, and reencrypt the same stream
with different cipher seeds to your video device.

> Rather, there will be an arms race that goes back and forth.  Today we're
> in the loser category, we can't record our cable and satellite based HD
> signals.   In the future, we'll move into the winner category.  I suspect
> that _eventually_ we will win but they will always counter.

As long as people still buy the product, the content providers will be
as restrictive as possible.  Hacking/cracking always has been and will
continue to be a race.

> Consumers aren't interested in that game, only us.    Few want a
> technology that can record their shows today, but might stop working
> tomorrow.

Few consumers know anything about any of this technology.  
The just want to plug it in and turn it on.  
Very few consumers have a digital link from their player to their display.