Screen does not support HDCP - HELP

[SussexWolf]

Sky Q 2TB box and new LG C4 tv. All working fine, then HDMI switching stopped working reliably, then the dreaded blue HDCP screen tonight. The tv definitely supports HDCP and has HDMI 2.1 ports. It was all working fine before, same cables. Having read this forum, rebooted the Sky box, and all working again. Clearly it's a Sky Q box issue. 

Hopefully we will be moving soon, and I will send this junk back to Sky. 

[Tomahawk1978]

I had this blue screen fault on and off for months but finally resolved it this weekend. I had a sky HDMI cable, the one with the pink connector one end and black connector the other. I then swapped it for a different HDMI cable but it was another sky one with pink one end and black the other - same problem. I then swapped the HDMI cable with a completely new unbranded HDMI cable and the problem has gone. The picture is also way better. Hope this helps for others. I have a Samsung TV btw.

[Chodley]

I seriously doubt the picture is any different - though placebo effect is real - unless you've changed the video output settings.

[Tomahawk1978]

the colour/brightness definitely changed. maybe not the quality

[SussexWolf]

I was also having the BSOD after changing my tv, and also found the Sky Q box would not reliably switch the AV input on the tv. I tried different settings, and swapping around the HDMI cables I had, having initially used the Sky one, but the problems persisted. As a last resort, I then ordered a new HDMI 2.1 certified cable from Amazon, and similar to @Tomahawk1978 the problems have gone and my picture is definitely improved - even my wife commented on this before knowing I had changed the cable. 

So my recommendation would be to try a new HDMI 2.1 certified cable if everything else fails. My UGREEN only cost £7 from Amazon, so no need to  shell out for a super expensive one either. No, I don't get any commission for mentioning the company of the cable or the supplier! 

[Chodley]

Unless the cable let the box switch to 10bit (and you're on UHD HDR content) or  TV decided to use a different picture settings profile for some reason (both of which are possible) then the picture quality cannot change. It's a series of numbers describing the image. Millions of them per frame, 50 times a second. Those numbers either get through the cable intact or they get mangled and that causes grey snow or blank screens. They can't half kind of make it. It's not like the old analog signals where "close" to a good signal is possible

[SussexWolf]

The fact the signal is digital, and the HDMI pin layout is backwards compatible through its versions, does not mean that either the ports or cables cannot have an impact on picture quality when at least one of the devices supports the more recent HDMI standards. In my case, my LG C4 supports HDMI 2.1 inputs. Put simply, a HDMI 2.1 certified cable allows a greater bandwidth and hence dynamic range, than a cable certified to a prior iteration of HDMI standards. There is now even a HDMI 2.2 standard, which further increases bandwidth, although as yet there are few if any devices which can take advantage of this. 

[cuke]

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@SussexWolf wrote:

I was also having the BSOD after changing my tv, and also found the Sky Q box would not reliably switch the AV input on the tv. I tried different settings, and swapping around the HDMI cables I had, having initially used the Sky one, but the problems persisted. As a last resort, I then ordered a new HDMI 2.1 certified cable from Amazon, and similar to @Tomahawk1978 the problems have gone and my picture is definitely improved - even my wife commented on this before knowing I had changed the cable. 

So my recommendation would be to try a new HDMI 2.1 certified cable if everything else fails. My UGREEN only cost £7 from Amazon, so no need to  shell out for a super expensive one either. No, I don't get any commission for mentioning the company of the cable or the supplier! 

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I've been using HDMI 2.1 certified cables for a few years now and never once had any connection issues. Thus I'd also recommend them as I doubt if the Sky supplied ones are of as a good quality as those. In fact all my cables for every device connected to the tv are now the same. They're not expensive so worth a pot for anyone having issues.

[PandJ2020]

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@cuke wrote:
They're not expensive so worth a pot for anyone having issues.

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That's the thing... But I overhead a salesperson in a rather well known store stating that the £60 cables they sell are far superior for those precious bits...

The Q only requires 2.0 so the supplied cable should suffice.  (Does for me)

[SussexWolf]

The Sky supplied cable used to work absolutely fine on my 8 year old Sony 4k tv, but it didn't work reliably on my 2024 LG C4. Same box, same cable, different tv. Tried updates, changing settings on both box and tv, and still had issues. Changed the cable to a £7 HDMI 2.1 certified cable, and works perfectly. I can't really say anything else. 

[Chodley]

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@SussexWolf wrote:

The fact the signal is digital, and the HDMI pin layout is backwards compatible through its versions, does not mean that either the ports or cables cannot have an impact on picture quality when at least one of the devices supports the more recent HDMI standards. In my case, my LG C4 supports HDMI 2.1 inputs. Put simply, a HDMI 2.1 certified cable allows a greater bandwidth and hence dynamic range, than a cable certified to a prior iteration of HDMI standards. There is now even a HDMI 2.2 standard, which further increases bandwidth, although as yet there are few if any devices which can take advantage of this. 

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Yes it does mean exactly that.

the pin layout is obviously irrelevant. It would have been abandoned years ago if they didn't maintain that.

The fact it's a digital signal 100% means unless  the higher bandwidth is being used to send a higher res / colour depth picture, the picture does not benefit from the higher quality cable.

you send 1080i through a HDMI 1.4 certified or a 2.1 certified cable and the numbers coming out the other end will be identical.

You get lucky with a good quality, short, 1.4 certified cable and do the same with 2160p/10bit and the exact same is true.

Another way to consider this - tell me how those numbers, if they change even slightly, can even produce a picture when you consider hdcp and how encryption actually works.

[SussexWolf]

Sorry, but your understanding is not entirely correct. Yes the signal is digital, and so yes "numbers" are passed between the devices. But HDMI works using a handshake process to establish and maintain the connection, and all involved components, including the cable, must support it properly. That's how the tv knows what standard of video and audio is being passed to it, and hence which it should select to reproduce it, including any enhancements it might apply. If the handshake doesn't work, the connection will not be reliably established and/or the best available picture will not be available. 

As I said, in my case when switching to a new LG C4 from a 7 year old Sony 4k tv, having kept the exact same Sky Q box and Sky HDMI cable, I went from a reliable connection to an unreliable one with the new tv. Having tried different settings on both Sky Q and tv with no luck, I purchased a cheap HDMI 2.1 certified cable, and the connection is now reliable and the picture quality is improved. It's not a placebo effect, as my wife noticed the improved picture quality before I told her I had changed the cable!

For the record, I'm not a cable fanatic, and I did study digitial electronics at University. A poor quality or under spec cable can make a difference to digital signals eg because it cannot sustain the signal bandwidth, permits too much noise, etc. 

[Chodley]

What do you believe the handshake actually does?

The only part the cable plays in it, by the way, is carrying voltages representing either 1s or 0s along its wires at an extremely high switching rate. You know this from your course so I don't mean to be patronising. It does need to be high enough quality to do that reliably because there is no - well, very little - opportunity for error correction, unlike (for example) ethernet. I agree a poor quality cable can affect the signal. But if it deteriorates to the point a 1 can no longer be reliably distinguished from a 0, you lose the image. It doesn't "not look as good". You see the same effect in satellite transmissions in bad weather. Very rapid loss of coherent image followed by "no signal". 

This is a good thread on the same subject https://forum.videohelp.com/threads/394232-does-HDMI-have-Error-Correction

[SussexWolf]

Thanks for the link, I read that. I wasn't saying the cable itself provides any signal or control, but it still needs to cleanly pass the entire signal between the devices. What you're continuing to miss is that the bandwidth is what's really changing in each HDMI generation, and in practical terms, that stresses the cable's ability to pass the entire signal cleanly. Cables are tested at different data rates, and not all will be able to reliably transmit the full bandwidth. The article below on one hand supports your general point, but then caveats that by saying the exception to the rule "most hdmi cables are fine" is with the introduction of HDMI 2.1, which is exactly what I experienced. My old Sony 4k tv only supported HDMI 2.0 and 4K HDR10. My new LG C4 supports HDMI 2.1 and the likes of Dolby Vision. The relatively old Sky Q 2TB box and Sky HDMI cable played nice with the Sony TV, but needed a HDMI 2.1 cable to play nice with the LG C4. 

https://www.bluejeanscable.com/articles/bad-reasons-to-upgrade-hdmi-cable.htm