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

[Sean Cier]

Alex wrote:
> Brad Templeton wrote:
>> Sean Cier wrote:
>>> protection: DVI+HDCP means DVI + copy protection, while HDMI basically
>>> means DVI+HDCP+Audio+BidirectionalCommunications
>>
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?
I hadn't meant to imply that HDMI without HDCP was even a possibility -- 
even if there's any chance it's technically or contractually possible, it's 
nowhere near likely to happen.

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.
Exactly.
Just because the transmitter and receiver support HDCP, one does not
have to use it unless the content provided requires that level of
protection.
Which we have to assume will be the case for all content one day, likely 
before long.  Of course, that's not a guarantee -- look at the original red 
book spec and you'll see that even CDs have a 'copy protection flag' bit, 
which is universally ignored.  But even given the chance market forces 
dictating that none of this copy protection (in particular the broadcast 
flag) is ever flipped on, we have to assume it will be.

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.
And even beyond the technical challanges are the economic issues.  E.g. 
who's going to pay for updates to devices with revoked keys, or replacing 
those devices that aren't upgradable -- the studios who don't make the 
hardware or the hardware manufacturers who don't drive the revocation 
decision in the first place?  And more significantly, what kind of consumer 
backlash are we going to see the first time several tens of thousands of 
consumers discover their TVs will suddenly no longer play the latest DVDs or 
TV?  That's not just bad for the brand's reputation, it means money spent 
for customer support.  And when it comes down to the bottom line rather than 
abstract theories and paranoid speculation, the affected companies will 
really have to take a good hard look at how much real money this technology 
is actually saving them.

-spc
--
 /- Sean Cier <[EMAIL PROTECTED]>  -\
( Everyone should believe in something; I believe I'll have another pint )
 \- http://www.PostHorizon.com/scier   -/
___
mythtv-users mailing list
mythtv-users@mythtv.org
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

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

[Brad Templeton]

On Mon, Jan 17, 2005 at 09:52:42PM -0800, Alex wrote:
> 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.

What I mean is, today if you had a set top box which would only give
you some significant part of your programming via HDCP (ie. for
example all your non-OTA, plus all your OTA with BF set) this would be
a hard sell, because too many people would not accept it, they don't
have HDCP.  They don't even have DVI on their older sets.

A few years from now, they hope that this changes, and nobody refuses
to take an STB just because it uses HDCP.
> 
> The point of HDCP is to make the content providers comfortable enough
> to enable these devices to play it.

Well, that's what they say, isn't it?   History shows this to be false,
that the vast majority of the content providers in the end, if they can't
have their way on DRM, still release the content without DRM.   However,
the CE companies have bought into it anyway, largely because it creates
barriers to entry for small competitors and open source competitors.

Or so it is suspected.  They would not say such in public.  Though I did
get one to say in public that it's all there because they have to do
something (even something that won't work or won't work for long) until
they can figure out what the hell is going on.

> 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.

Indeed, though one has to assume that's going to change.  I mean
from a technical standpoint, going digital all the way is what you
want.   In theory, the pixel captured on the digital camera should
stay digital until it is converted into the signals that adjust the
DLP mirror in your TV for that specific pixel.   Signals should not
be transcoded, just decompressed at the final stage.Though it is
OK to use lossless methods and compressed stream edits, plus of course
overlay channels with alpha for OSD.   We are not there yet but want to be.
 Unfortunately this is also perfect for DRM.
___
mythtv-users mailing list
mythtv-users@mythtv.org
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

Re: [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.
___
mythtv-users mailing list
mythtv-users@mythtv.org
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

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

[Brad Templeton]

On Mon, Jan 17, 2005 at 04:53:59PM -0500, Sean Cier wrote:
> clarity's sake, but wanted to point out that HDMI does not mean DVI + copy 
> protection: DVI+HDCP means DVI + copy protection, while HDMI basically 
> means DVI+HDCP+Audio+BidirectionalCommunications (to negotiate formats, 

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.

However, what I said remains true, their goal is to marginalize unencrypted
DVI from the market, so that so few TVs exist that can only take clear DVI
that it becomes practical to convince creators of set top boxes that they
can output nothing but HDCP based signals and not hurt their market.

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.

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.

> 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.  It's 
> a slightly fuzzy area since the industry(*) could fight back against *some* 
> kinds of cracks by using key revocation -- but key revocation is an 
> entirely untested technology, and is likely utterly, laughably impractical 
> in the real world.

They have developed whole new rafts of key revocation tech that, in theory,
let them revoke only the solo device that was compromised.   In addition,
now that more and more devices are getting flash card slots or even
internet connections, one can imagine regimes where, just like satellite
vendors sending out new smart cards, TV owners are sent out updates to
replace compromised keys.

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.

> and MPEG2 encoders which, as Brad suggested, Moore's law will inevitably 
> bring us -- will mean that HD input to our Myth boxes will be a real 
> possibility long-term, with likely the only 'hack' being obtaining a 

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.

Consumers aren't interested in that game, only us.Few want a
technology that can record their shows today, but might stop working
tomorrow.   I guess that's what they have in the bootleg satellite "industry."
The companies do countermeasures, ship out new smart cards to paying
customers, it goes back and forth.  Sometimes your satellite gives you
free everything, sometimes it barely gives you anything.  Since this is
a difference of paying $100/month to get the same stuff, people put up
with it -- some people.

Here, we're talking about the difference between renting/buying their crippled
but fully able to record proprietary PVR and for a not too different
price getting an open PVR which has more features but might lose the
ability to record if the key it uses is disabled.

> Of course, for OTA or unencrypted cable, using a GnuRadio card
>  and ATSC (or QAM) 
> software codec could result in a more elegant solution even in a 
> post-broadcast-flag era; but that doesn't necessarily work for encrypted 
> cable signals, and its legal status for OTA remains to be determined 
> (though it would have to be a pretty flaky legal decision to make that 
> hardware illegal).

The harder question is, since it was crazy to think about making hardware
illegal, is it much more crazy to imagine them trying to ban the software
too?  Decss is banned, though not by the FCC.  The FCC is overstepping its
bounds in making hardware illegal but they did it.

> Even better would be if the EFF and others succeeded in getting the 
> ridiculous broadcast flag struck down in court (well, more specifically, 
> the FCC's self-granted oversight over the entire data chain and hence the 
> entire technology industry).  And/or maybe a cable tuner PCI card that took 
> a CableCard and delivered clear MPEG2 bitstreams or, hell, even 
> uncompressed frames... hey, a guy can dream, can't he?

We hope to win that fight, but I fear it's not the last fight.  The
juristiction of congress over hardware is harder to fight.  We even lost
a battle over their jurisdiction over software.  But not the war.
___
mythtv-users mailing list
mythtv-users@mythtv.org
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users

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

[Sean Cier]

Brad Templeton wrote:
Then the push will come from the studios to get rid of component video
and DVI.  (They are already fully underway with DVI, almost all new
TV sets have HDMI instead, which is backwards compatible with DVI.)
Uncertain how that battle will go.
Just wanted to clarify here; I presume you were just simplifying for 
clarity's sake, but wanted to point out that HDMI does not mean DVI + copy 
protection: DVI+HDCP means DVI + copy protection, while HDMI basically means 
DVI+HDCP+Audio+BidirectionalCommunications (to negotiate formats, send IR 
signals, etc) with a new connector.  So nothing about HDMI is really about 
copy protection -- it just happens that the version of DVI that HDMI is 
based on already included copy protection (HDCP) -- and AFAIK, nearly all 
currently-for-sale displays which have DVI input already have DVI+HDCP (as 
do many or possibly most video sources with DVI output, i.e. HD tuners and 
some DVD players).

If anybody doubts this, a bit of searching reveals $30 dongles that take 
HDMI as input and send DVI output, simply by stripping out the 
'unneccessary' bits of HDMI; no decryption involved, since the encrypted 
video stream is the same between the two.

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.  It's a 
slightly fuzzy area since the industry(*) could fight back against *some* 
kinds of cracks by using key revocation -- but key revocation is an entirely 
untested technology, and is likely utterly, laughably impractical in the 
real world.

(*)I'll leave determining *which* industry as an exercise to the reader.
So even if full-resolution component video and 'vanilla' DVI become a thing 
of the past, using DVI+HDCP or HDMI -- currently the state-of-the-art 
connector, with no suggestions of anything higher-tech on the horizon -- and 
MPEG2 encoders which, as Brad suggested, Moore's law will inevitably bring 
us -- will mean that HD input to our Myth boxes will be a real possibility 
long-term, with likely the only 'hack' being obtaining a 'libhdcp' the same 
way you obtain 'libdvdcss' now (and, worst-case, the use of an external HD 
tuner box used the same way cable tuners are used by many now).  Of course, 
it would be nice if even this turned out not to be necessary for our 
fair-use manipulation of the datastream, but if it does, it's not the end of 
the world.

Of course, for OTA or unencrypted cable, using a GnuRadio card
 and ATSC (or QAM) 
software codec could result in a more elegant solution even in a 
post-broadcast-flag era; but that doesn't necessarily work for encrypted 
cable signals, and its legal status for OTA remains to be determined (though 
it would have to be a pretty flaky legal decision to make that hardware 
illegal).

Even better would be if the EFF and others succeeded in getting the 
ridiculous broadcast flag struck down in court (well, more specifically, the 
FCC's self-granted oversight over the entire data chain and hence the entire 
technology industry).  And/or maybe a cable tuner PCI card that took a 
CableCard and delivered clear MPEG2 bitstreams or, hell, even uncompressed 
frames... hey, a guy can dream, can't he?

-spc
--
 /- Sean Cier <[EMAIL PROTECTED]>  -\
( Everyone should believe in something; I believe I'll have another pint )
 \- http://www.PostHorizon.com/scier   -/
___
mythtv-users mailing list
mythtv-users@mythtv.org
http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users