[Info-vax] OT: "HDMI 2.0 cables"

[Dirk Munk]

johnwallace4 at yahoo.co.uk wrote:
> On Thursday, 22 January 2015 23:34:18 UTC, Marc Van Dyck  wrote:
>> MG has brought this to us :
>>> What an incredible scam, I noticed that some places are now
>>> offering "HDMI 2.0" cables... while those don't even exist.
>>>
>>> How many people will be suckered into buying imaginary "HDMI
>>> 2.0" or "HDMI 4K cables"...?
>>>
>>> Then people talk about file sharing/piracy, that /that/ is
>>> supposedly killing the 'computer industry' (and what-not).
>>>
>>> If this kind of cutthroat racketeering was what DEC 'lacked'
>>> all these years and that's why VMS 'failed', then maybe it
>>> should be considered a badge of honor almost.
>>>
>>>    - MG
>>
>> Oh, speaking about cables, just take a look at the audiophile market,
>> and you will even find optical fiber cables... with gold-plated
>> connectors ! Or USB cables "made specially for music" costing more
>> than $2k apiece. I don't blame the industry, why not take advantage
>> of that, if there are people naive/idiot enough to buy ?
>>
>> --
>> Marc Van Dyck
>
> Wrt HDMI cables and also wrt the audiophile market, some potentially
> interesting reading at
> http://www.bluejeanscable.com/store/hdmi-cables/hdmi-cable.htm
> and at
> http://pwbelectronics.co.uk/
> Compare and contrast.
>
> Back to HDMI for a moment. It's a cable for carrying digital data. Folk
> with a networking or digital comms background might well expect such
> data transmissions to generally have error checking (and maybe correcting)
> components included because digital transmissions aren't 100% reliable.
>
> Even the usual network-level error checking isn't 100% reliable; if you
> shift enough data around, eventually you stand a chance of seeing
> "%RMS-F-CRC, network DAP level CRC check failed" (whoops, on-topic?).
>
> It's quite hard to get a definitive answer as to whether HDMI has error
> checking on the wire, without reference to the HDMI spec itself ($$$).
>
> After some digging a couple of years back I think it does but it's hard
> to be sure. It doesn't have retransmissions because of the intolerable
> delay a NACK and retransmission would introduce.
>
> Assuming the error checking data is there, if I were designing a receiver
> chip I'd want to incorporate some counters so I could tell if the physical
> layer was error free, or if the error correction was being used (and if so,
> how much - like you can with NCP>).
>
> As far as I can tell, generic HDMI kit doesn't have that capability. Which
> is a shame, because if it did have that capability you could immediately
> see in any given circumstances if there was a detectable difference between
> a $20 HDMI cable and a $200 cable.
>
Quality differences between HDMI cables certainly exist. Look for tests 
on the internet and you will find these differences. However a $200 HDMI 
cable is a bit over the top.

> Going back to HDMI V2.0: somewhere on the web I've read that the HDMI
> people don't allow HDMI cable vendors to advertise a version number
> with cables.

True, however the HDMI organization has failed so far to specify cables 
for a 600MHz clockrate, and to name those cables.

>
> Isn't technology fun when it meets marketing.
>