OK, I know this has been dealt with before. But HDMI is a wider-spread technology now and HDMI kit is cheaper.
- HDMI's bandwidth exceeds SPDIF, allows 8 channel 24/96 PCM. Yaldi.
but
- HDCP cleverly encodes everything for DRM.
OK. My questions are (for audio only):
Do you need to own a licence for the content to prevent HDCP working?
And/Or do you need to own a licence for HDCP decoding?
I have seen mentions of "membership" in order to build HDMI kit. Is this the case?
If content is unlicensed, is HDCP still a problem, or does it then become like any other digital interconnect?
Can HDCP be physically hacked and is this illegal if you own content licences?
And if HDCP is prohibitively expensive to develop, surely my best bet is to get a cheap HDMI receiver, gut it of everything except the HDMI processing and build a high quality DAC off the end of that? And then sell kits for billions to greedy DIYaudioists?
Any and all help greatly appreciated
- HDMI's bandwidth exceeds SPDIF, allows 8 channel 24/96 PCM. Yaldi.
but
- HDCP cleverly encodes everything for DRM.
OK. My questions are (for audio only):
Do you need to own a licence for the content to prevent HDCP working?
And/Or do you need to own a licence for HDCP decoding?
I have seen mentions of "membership" in order to build HDMI kit. Is this the case?
If content is unlicensed, is HDCP still a problem, or does it then become like any other digital interconnect?
Can HDCP be physically hacked and is this illegal if you own content licences?
And if HDCP is prohibitively expensive to develop, surely my best bet is to get a cheap HDMI receiver, gut it of everything except the HDMI processing and build a high quality DAC off the end of that? And then sell kits for billions to greedy DIYaudioists?
Any and all help greatly appreciated
Ok I'll try to answer your questions (all replies are to the best of my knowledge).
Not sure what your asking here.
To manufacture HDCP compliant devices you require a licence.
I believe a licence is all that is required.
Most sorces devices that are HDCP compliant demand HDCP even for encryption free content. The only way around HDCP is if your building the source and receiving devices (not overly practical).
I vaguely recall something about HDCP strippers, but they were removed from the market pretty quick. As for legalities, I suppose that'll depend on the country you live in.
There are other options. Standalone HDMI DAC boards are available (fully HDCP compliant) from a couple of manufacturers, which will be easier to mod if you want to replace the DACs/output stage etc. I have a prototype here that I'm looking to make available to the DIY community, so feel free to ask any questions and I'll do my best to answer (note i'm not overly technical, just someone with a few contacts in asia).
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thanks so much - that was really helpful!
Any chance of a link/block diagram or somesuch of the prototype you mention?
You answered it later, but what I was asking first off was if owned licenced content used HDCP - as you said, most devices use it anyway. Since I want my DAC to be compatible with many devices I'll need to cope with HDCP.
Thanks again
Kit
Any chance of a link/block diagram or somesuch of the prototype you mention?
You answered it later, but what I was asking first off was if owned licenced content used HDCP - as you said, most devices use it anyway. Since I want my DAC to be compatible with many devices I'll need to cope with HDCP.
Thanks again
Kit
I wouldn't make too much noise about that if I were you or you might find your device on the key revocation list.
Searching about, I found this: http://www.lektropacks.co.uk/view_product_standard.php?product=1001185&sub1=&show=
This looks hackable, and fingers crossed is HDCP compliant (have emailed to check).
Its decoding looks pretty limited, especially from what I've read elsewhere. However that won't be a problem, will it? surely once the audio stream is separated I can just hook it up to my own decoding chips before then putting it through to my own DAC. Right?
It seems such a bloody fuss all this HDCP it seems almost easier to just buy a high-end receiver. I can't understand why it's so stupidly done - SPDIF is pretty terrible, but thew only alternative is almost impossible to access! Totally mad.
This looks hackable, and fingers crossed is HDCP compliant (have emailed to check).
Its decoding looks pretty limited, especially from what I've read elsewhere. However that won't be a problem, will it? surely once the audio stream is separated I can just hook it up to my own decoding chips before then putting it through to my own DAC. Right?
It seems such a bloody fuss all this HDCP it seems almost easier to just buy a high-end receiver. I can't understand why it's so stupidly done - SPDIF is pretty terrible, but thew only alternative is almost impossible to access! Totally mad.
I entirely agree. HDCP has done nothing to stop the spread of copy protected work. And is a major pain in the *** for the DIY community and small audio firms (even some major players like McIntosh didn't implement HDMI audio in their first HDMI based receivers because of the demands the licence requires).
The output is analog, the end user would have to modify for digital if they wanted that (no different to modifying a full receiver).
It was hacked a while a ago.
http://www.switch-box.com/S_PDIF_installation/Entries/2008/10/30_Cypress_CLUX-11SA.html
http://www.switch-box.com/S_PDIF_installation/Entries/2008/10/30_Cypress_CLUX-11SA.html
What would be good would be to find a small HDMI manufacturer to do it for you: the pinout etc is free, so you can make the board, but you ask them to program the chip -and you pay for it. If you propose an interesting price, they may be tempted - it would only take them 5 minutes to do it, and say, getting 150$ for 5 minutes of extra work is always welcome! It should probably be legal. (what wouldn't be, would be to batch copy the EEPROM... Thinking of an idea?).
Thing is, it's SPDIF out, not I2S, which means the hack needs hacking really, plus it's waaay overpriced! Still, shows how easy it is
Why waste time and effort trying to defeat HDCP ? Whatever widget you come up with will have to go into an enclosure of some sort so it might as well be a playback device with added digital outputs in parallel with onboard dacs.
For some, the prospect of 13 wires dangling out of the back holds little appeal.
Yes, but I think also very few people have an amp with 4 simultaneous SPDIF inputs! It isn't much use as it is, plus SPDIF is awful!
I daresay the ICs are designed so as to make it impossible to read the EEPROM. I mean, since HDCP can apparently be cracked with just 39 keys, anyone with 39 friends would have unlocked it ages ago. I imagine it's a case of write/erase only.
Hovever, it is academic to remember that unless you're mixing inputs, only one receiver is ever needed. This can apparently be bought for not too much.
It seems ridiculous that HDMI is so expensive - there is no function to the cost, other than to force out people like us, it costs nothing to maintain the database, and if it's for security reasons they really are stupid.
I mean, HDMI is superior to the only alternative, SPDIF, incomparably. It is long overdue in the audio sector. Why big business feels they must keep it to themselves is perhaps just something for the socialists to ponder.
And fewer still have inputs for 13 dangling wires though most would probably send the outputs to a surround sound processor and the better ones have more than enough digital I/O.
I think you're overlooking the fact that this hack must be aimed at the DIY community. I am not aware of any commercial amps that can take 4xSPDIF inputs, and for the average consumer, s/he wants either analogue out or s/he'll buy an HDMI receiver. Even if I'm wrong, SPDIF introduces significant error to the signal, and will anyway still have to be decoded separately. Even for the weirdo with the 4xSPDIF amp, s/he still has to worry about quality at that stage. I2S of course is useless unless you shove it right back into another circuit board, but like I said, show me the unhappy consumer with the 4xSPDIF amp and I'll show you a lot more interested in modding DACs (here on this forum!).
Anyway, it doesn't matter - no need for us to argue!
I personally think the hack is much too pricey to be much use to anyone anyway.I'll let folk know how i get on when i get round to modding my own
This 4ch amp thing is a red herring. It is about access to uncompressed multichannel audio and something better than a two channel mix-down. Once it is unfettered and in a practical format you can do what you want with it. As for SPDIF introducing significant error, that is just plain cobblers.
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