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