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

[johnwallace4 at yahoo.co.uk]

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.

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. 

Isn't technology fun when it meets marketing.