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Hooking up Sky HD to CRT PJ via HTPC?

Discussion in 'Sky Digital TV Forum' started by Mr Spoons, Jul 27, 2005.

  1. Mr Spoons

    Mr Spoons
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    I have a sony G70 CRT hooked upto a HTPC via RGBHV with Powerstrip (to get the resolution spot on) when Sky HD comes along I want to hook this into the HTPC, but am unsure of the best way.

    I guess I need a DVI or HDMI capture card, routing through Dscaler to the Sony? Will I need to worry about copy protection to do this? I'm not interested in recording at this stage. Will the high bandwidth mpeg signal cause any issues i.e. will I need to run the latest spec PC?

    Anyone any ideas?

    Mr Spoons
     
  2. quig

    quig
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    That won't be possible. Firstly, to allow copy protected output to be viewed on an unsecure PC would defeat the point of the copy protection. Such output will only be viewable on PCs in future with 'trusted computing' - HDCP like protection in the operating system and hardware.

    Secondly, the bandwidth is just too high for current systems to cope with, even with the unencrypted component connections on the first generation boxes. Your only hope would be an output of the broadcast stream, such as a firewire output on the box, or free to air/non-VideoGuard broadcasts. Even if this did happen, H.264 video is too resource intensive for decoding with a PC.

    Your only option seems to be non-PC based scaling of the component output, if you need it. There is no chance that you will be able to legally convert HDCP outputs to an unencrypted form for either your PC or your CRT.
     
  3. Mr Spoons

    Mr Spoons
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    Quig,

    Thanks - I'll continue to research I'm not too clear on how HDCP works other than I think it's there to protect the integrity of the signal rather than provide copy protection - although I've read else where that HDMI was designed to provide copyright protection - the studio's have bought into it for this reason. Still being data and being encrypted means it will not be long before someone develops a codec for it. DVD region free maybe?

    I've sure the newer spec technologies for i/o bandwidth i.e. PCI-e SATA (1.5 - 3gb bandwidth) and MP4 (I believe Sky is using MP4 for HD) the humble HTPC will have enough power.

    The other way is a HD DVB-S card (available today in the US) with a CAM for Sky-HD, this removes the sky box 100% from the connection and I assume the then HDMI/DVI HDCP encryption - but I know the encryption in Europe is different to the US - Still as far as I can find out Sky encryption keys are carried on the viewing card.

    Interesting topic though I'm sure us HTPC users will find a solution, just might take time - just hope it’s not too long :rolleyes:
     
  4. quig

    quig
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    HDCP is there to protect content. It is a form of Digital Rights Management. Wikipedia has an article about it here, if you want more information.
    According to the article, Niels Ferguson has already broken the encryption - but we can be sure that it won't be legal to do so.
    The codec used is a minor problem - some high end workstations at present (such as those with multiple core, 64 bit processors) are able to decode H.264 MPEG4. You can test this by attempting to play the Quicktime high definition trailers with the Quicktime 7 for Windows player. Although most PCs at present are unable to decode H.264, in a few years it will be possible with most new HTPCs. Also, future graphics cards will provide hardware support for the codec, reducing the CPU requirements.

    It is the data from HDMI and DVI outputs that is difficult to input to a PC. This is output from set top boxes with no relation to the codec in use, uncompressed. For this reason the bandwidth requirements are higher than dealing with compressed H.264 video, for example. Only broadcast level equipment is currently able to record the output from a HDMI/DVI port.
    I doubt that DVB-S cards are available in the US! The cards in use over there will be ATSC only. Yes, DVB-S cards can be used to receive HDTV broadcasts in Europe, such as Euro1080, HD Forum and ASTRA HD, but there are some problems with this.

    Firstly, what CAM? Sky does not provide a CAM for its standard definition broadcasts. Although at this time it is unknown whether this will be the case for Sky HD broadcasts, it is unlikely to change its mind, especially with so much pressure from the American movie industry to keep its content secure.

    Secondly, Sky may decide to broadcast Sky HD in DVB-S2, since it is producing new boxes. This would allow them to use the bandwidth more efficiently than DVB-S. However, standard DVB-S cards do not support it. I don't know whether existing cards can be updated, or if DVB-S2 cards will be available in the future.

    As you can see, even with a fast HTPC capable of decoding MPEG4 AVC, you're not going to be able to receive Sky HD with it unless they release a CAM for whatever encryption system they will be using for Sky HD, or include a firewire port on the boxes, as in the US.
     
  5. Stephen Neal

    Stephen Neal
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    Not quite the case actually. ATSC 8 VSB is used for OTA broadcasts in the US, but a significant proportion of US satellite broadcasts use DVB-S techniques, and DVB-S video cards with CAMs are in use in the US for SD and HD reception AIUI. (QualiTV receivers are used in the US as they also allow 4:2:2 reception - unlike most standalone receivers)

    This is true - though it is now possible to use 3rd party programmable CAMs to emulate a Videoguard CAM apparently. You still need a valid Sky subscription and card, and you have to code your Digibox serial number into the CAM (to continue the "card marriage" apparently)

    This may not last - and will almost certainly not work for Sky HD broadcasts.

    Additionally the Sky EPG is compressed using proprietary techniques that have not been widely reverse engineered. (They aren't encrypted though)

    Yep - it is VERY unlikely Sky will introduce a CAM or a Firewire output. Whether they use DVB-S or DVB-S2 is not clear - but I would expect any new receivers to incorporate DVB-S2 if at all possible - as it offers major cost reductions for transmission.

    Your other points are dead-on.

    Addressing the OPs original comments:

    Connecting a DVI+HDCP or HDMI connection to a PC is not practical currenlty. Even if you break the HDCP encryption (it is for copy protection/rights management as you say) you still have to cope with up to 1.5Gbps worth of data - which is a LOT of bits to handle (more than Gigabit ethernet can carry in real-time...) Similarly digitising an analogue HD component signal would require similar levels of bandwith - massively more than most PCs can cope with.

    You CAN get SDI input cards for PCs - which allow for about 1/6 th of the bandwith of an HD signal - but HD levels are still beyond most current PCs.

    HD-SDI cards are available for PCs and Macs (HD-SDI is a broadcast HD uncompressed video connect - not the same as HDMI or DVI - but using similar data rates) - but they are VERY specialised. and additional specialised hardware and PC design etc. is used for uncompressed HD video processing in real-time.

    In the US the only real consumer systems for getting HD into a PC are either using an ATSC 8-VSB OTA, QAM cable or a DVB-S PCI or USB2.0 card for receiving HD transmissions, or a Firewire output from a set-top box. All of these source the HD as broadcaster compressed MPEG2 - not uncompressed.

    None of these solutions are likely to be possible with Sky HD - it is a sealed box solution with only HDMI output. If your HTPC could take HDMI and output HD analogue RGB VGA then it would be in breach of the HDCP licensing I believe...
     
  6. Mr Spoons

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    Great posts thanks :) a very interesting subject what's become clear to me is the data rates of HD are way higher than I expected.....

    Also it is possible to currently use a DVB-S card and sky CAM with your existing sky card, which is where I was looking for a Sky-HD answer.

    I'm happy to be legal('ish) well as legal as backing up DVD on to HD was/now is. but I don’t want to splash out a small fortune for a LCD or 56th. gen Plasma (lol) just to enjoy sky-hd via the Sony CRT.

    I've also picked up elsewhere that handling an analogue signal can be just as good when using a CRT PJ. It's the digital domain where this becomes an issue. That said as long as everything matches and is scaled correctly digital - digital has to be cleaner and more detailed.

    Interesting area, I know that DVD's are often engineered to "blur" the picture to attempt to recreate that Roxy experience i.e. a filmic look - so will the studio's continue this? can't imagine seeing nasal hair on the heroin!

    Still I look forward to Blue ray and HD content on that through the HTPC.

    I think we all know it's only a matter of time.

    Thanks again for informative posts fellas :cool:
     
  7. Stephen Neal

    Stephen Neal
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    Yes - given that CRTs (both direct view and projectors) are inherently driven in the analogue domain the benefit of digital interconnection is lower in quality terms.

    As Sky have said their first generation receivers will have HD analogue component outputs, and it is likely that most (but not guaranteed to be all) material in HD will be output via these connectors, then there is little need to investigate digital to analogue conversion to connect to your projector. Just use the analogue outputs.

    HOWEVER - if you are interested in HD-DVD - then digital outputs may be your only source of HD, with the analogue outputs limited to SD or SD progressive resolution. Legal solutions to this may be non-existent...
     

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