HDCP Playback Scenarios

[Dave Baumann]

I've just been talking to Sapphire and they had some HDCP technical document (I don't know what exactly) and from that document they read the following scenarios regarding HD playback of content:

1. Source not encrypted: Plays
2. Source Encrypted, valid keys supplied: Plays
3. Source Encrypted, not valid keys supplied: No Display
4. Source Encrypted, analogue output: Plays

The common expectation is that SD content is displayed if there is no HDCP present, however where does this come from? According to these HDCP rules it, on the face of it, appears to be the case that HD content could still be played back via analogue with Macrovision being the only content protection.

 

[epicstruggle]

I've just been talking to Sapphire and they had some HDCP technical document (I don't know what exactly) and from that document they read the following scenarios regarding HD playback of content:

1. Source not encrypted: Plays
2. Source Encrypted, valid keys supplied: Plays
3. Source Encrypted, not valid keys supplied: No Display
4. Source Encrypted, analogue output: Plays

The common expectation is that SD content is displayed if there is no HDCP present, however where does this come from? According to these HDCP rules it, on the face of it, appears to be the case that HD content could still be played back via analogue with Macrovision being the only content protection.

Now that is quite interesting, to say the least. I wonder if MV wont go all crazy and display green fields every so often.

epic

 

[Geo]

So it just keeps getting worse? Now, poor bastard with dvi and no HDCP card is expected to switch cables to d-sub if he wants to see protected content? Can't even watch it in lowered resolution?

Oh, lovely.

 

[Dave Baumann]

http://www.videobusiness.com/article/CA6300812.html

OK, as HDCP is designed as a digital protection method only the HDCP rules themselves do not dictate what to do in the analogue playback scenario. This has been left as an agreement between the studios and hardware manufacturers.

 

[kyleb]

But surely they are going to require a secure system from end to end to alow playback of protected content and full resolution, and protected to the point at which it is downsampled for analog output. I mean that is how it is set to work with stand alone uints and basicly how it already does work for upsampling DVD players; PCs are bounr to be held to the same standards, eh?

 

[pascal]

So, I will have to go back to VGA.
Really doesnt make sense.

 

[Blazkowicz]

If it's true and we don't get restrictions with an analog signal, it's good news for us VGA users and for the owners of CRT 1080i HDTVs. Not only we'll have superior, angle independant image quality, but we'll have full res as well

 

[Tahir2]

On the media side, are there going to be two separate video streams (one HD and the other SD) or will there be some sort of rescaling for the lower resolution?

 

[London Geezer]

I've just been talking to Sapphire and they had some HDCP technical document (I don't know what exactly) and from that document they read the following scenarios regarding HD playback of content:

1. Source not encrypted: Plays
2. Source Encrypted, valid keys supplied: Plays
3. Source Encrypted, not valid keys supplied: No Display
4. Source Encrypted, analogue output: Plays

The common expectation is that SD content is displayed if there is no HDCP present, however where does this come from? According to these HDCP rules it, on the face of it, appears to be the case that HD content could still be played back via analogue with Macrovision being the only content protection.

Hey Dave,
On the AVforums there are a few threads with people confirming that analog output will be downscaled, but not downscaled to SD resolutions, a little higher than ED resolutions, something like 9xx*540 (can't remember the horizontal number, but it's 9 hundred something).
So, although it plays, it does so without giving you the best IQ possible on the screen, unless there is HDCP.

 

[kyleb]

It's 960x540, which is exactly 1/4 of 1080p; and the downscaling is optional, content providers can alow full resolution playback over analog connections if they like.

http://www.videobusiness.com/article/CA6300812.html

 

[Dave Baumann]

The article I linked to later explains it. HDCP itself is just a digital content protection mechanism; HDCP itself isn't setting the rules as to what should occur under an analogue playback system where the license keys cannot be present. What is occuring in an analogue scenario is decided outside of the HDCP element (and this will end up as an agreement between the movie studios and hardware manufacturers, however hardware manf's notoriously ignore this after a while - how long was it before region free hacks turn up as standard on DVD players?).

 

[London Geezer]

It's 960x540, which is exactly 1/4 of 1080p; and the downscaling is optional, content providers can alow full resolution playback over analog connections if they like.

http://www.videobusiness.com/article/CA6300812.html

Of course, "if they like". I guess the problem becomes figuring out which studio will do that, and for how long...

 

[kyleb]

Right, it is digital copy protection, which is exactly why they are requiring the option to downsample within the secure digital environment before converting to analog.

 

[London Geezer]

Right hold on, i have a question:

Does that mean that the studio can choose whether to allow either full HD playback, downsampled output or NO output at all through analog? That could get messy. No wait it's already messy.

 

[BlueTsunami]

Right hold on, i have a question:

Does that mean that the studio can choose whether to allow either full HD playback, downsampled output or NO output at all through analog? That could get messy. No wait it's already messy.

Supposedley its up to the content providers. They can choose to set a flag in the disk to downsample through analog.

 

[kyleb]

Yep, downsample though analog or be nice and let us have full quality are the options listed. I haven't seen anything to suggest any option "NO output at all through analog", and I doubt anyone would want one as that would create situations where the HD formats would be inferior to standard DVDs.

 

[Dave Baumann]

Does that mean that the studio can choose whether to allow either full HD playback, downsampled output or NO output at all through analog?

I'm not sure I've seen a scenario that says no output at all through Analogue - there is a flag that if it is present will downscale, if its not it will render at full resolution.

 

[kyleb]

Again, it seems clear to me that you'd get no output analog or otherwise as long as the path of the digital signal is not secure. I mean there is no point in protecting the DVI output if the digital video signal can be unencripted and captured directly on the PC.

 

[Dave Baumann]

No - you will get analgue output (its just a question of what res that analogue outpu is displaed at). Again, HDCP is only protecting the digital path, the HDCP rule specifically states that content plays when there's analgue playback.

 

[kyleb]

Again, HDCP is only protecting the digital path...

Right, but the digital path goes all the way from the disk to the display, or at least to the point it gets converted to analog. So surely analog output isn't going to do you any good as long as the content isn't protected from the motherboard to the card, or from the drive to the motherboard for that matter.