my thoughts on hdmi cables, and the randomness of potential data loss...

[idc]

v1c:
idc:. The cost of the equipment used to measure the cables was $205,000.

.

The cost of the equipment used to measure the cables is relevant ?

But apparently not the cost of the cable.

Did either the input source or the output source have any bearing on the delivered audio/video signals in said test ?

I mentioned the cost of the measuring equipment, the number of cables used and the time taken to do the test as a way of conveying the size and thoroughness of the test.

The cost of the cable turned out to be irrelevant with for example Monoprice (a US cheap brand) performing as well as if not better than many more expensive cables.

The input and output remained the same, only the cable changed, so any influence from either input or output was the same with all of the cables.

 

[idc]

Buckshar:
why do we need to do a blind test ...

surely with some planning, a test could be where a "cheap" decent - say fiver HDMI cable was used, and then say a real top end £100 one.

then with a high-end DSLR - with all settings set to manual to ensure consistancy, take a picture of both, and one should be able to show the difference for all to see ?

if its night and day as some people suggest, even if its a fairly subtle difference a decent camera should be able to pick up the difference.

In effect that is what the test I have been referring to did. You can see pictures of the waveforms and how clear the eye is in the article.

The reason why I think that blind testing is important and relevant is because even though the test found differences in the clarity of the waveform and eye and pronounced some cables at certain lengths as fails, going by HDMI protocols, in reality no signal degradation could be seen. The TV pictures had no snow, clicks etc.

So, if you want to say that HDMI cables are different, to be accurate you should say they are under lab conditions, but hook them up between your Blueray and TV and those differences do not matter (unless you use a huge length of cable, in which case it may).

 

[Anonymous]

professorhat:Mr Mellie:Most of the answers are subjective so how about a more scientific approach?

Take a known source, say the fist 1GB of any film you like and save as a file on disk on computer 1.

Read the computer 1 file and send via HDMI to computer 2.

Computer 2 captures the data and saves to disk.

Now compare the file on computer 1 with that on computer 2.

Can not be that hard can it?

Finding two computers which communicate not only via HDMI cables, but which can also communicate using the same protocols that Blu-Ray players use to send data to TVs - that may be fairly hard, yes.

The reason for putting the data on disk was to remove and Blu-Ray /
dodgy disk problems. A computer disk will always return the same data.
The protocol will be HDMI surely? All we want to test is the cable nothing else.

 

[Anonymous]

maxflinn:
for me the question that i'd love answered is how a supposedly inferior cable (in comparison to one deemed better) can seemingly lose data but not image consistency? if said data loss is significant enough to be noticed (remember, it's a supposedly inferior cable), and data loss is random, image consistency would be random, and noticed, to the same degree, imo..

if data loss is not random, i'd love someone to explain how or what, enables prioritisation of high value data whilst seemingly discarding data of a lesser value? as i assume would be neccessary to get a consistent picture, albeit one of lesser quality..

ta..

Getting back to the original question then, as I see it there are two types of corruption: 1s and 0s get transposed or data getting lost.

Either way I can not see this as deterministic, i.e. the same input gives the same output, after all this is what computer programs do not dodgy cables.

 

[The_Lhc]

Yes but there is currently no way of using an HDMI cable to transfer data between two PCs, it's a display connection, you'd need to come up with an entirely new set of protocols to allow them to talk to each other.

 

[Anonymous]

Mr Mellie:maxflinn:
for me the question that i'd love answered is how a supposedly inferior cable (in comparison to one deemed better) can seemingly lose data but not image consistency? if said data loss is significant enough to be noticed (remember, it's a supposedly inferior cable), and data loss is random, image consistency would be random, and noticed, to the same degree, imo..

if data loss is not random, i'd love someone to explain how or what, enables prioritisation of high value data whilst seemingly discarding data of a lesser value? as i assume would be neccessary to get a consistent picture, albeit one of lesser quality..

ta..

Getting back to the original question then, as I see it there are two types of corruption: 1s and 0s get transposed or data getting lost.

Either way I can not see this as deterministic, i.e. the same input gives the same output, after all this is what computer programs do not dodgy cables.

hi mr mellie.. i cant say i fully get your point.

anyways, the way i see it is this..

if a cable cannot send all the data at the required speed, and data loss is random, and this is noticeable to people in the sense that they can see visible on screen degradation of picture quality (however small) in a given movie scene, compared to a cable that does not lose data, then by the same token, they should be able, on repeat viewings of said movie scene, to also see the manifestations of the random data loss in the different ways it would have to appear..

however, if data loss is not random........

 

[professorhat]

Mr Mellie:professorhat:Mr Mellie:Most of the answers are subjective so how about a more scientific approach?

Take a known source, say the fist 1GB of any film you like and save as a file on disk on computer 1.

Read the computer 1 file and send via HDMI to computer 2.

Computer 2 captures the data and saves to disk.

Now compare the file on computer 1 with that on computer 2.

Can not be that hard can it?

Finding two computers which communicate not only via HDMI cables, but which can also communicate using the same protocols that Blu-Ray players use to send data to TVs - that may be fairly hard, yes.

The reason for putting the data on disk was to remove and Blu-Ray /
dodgy disk problems. A computer disk will always return the same data.
The protocol will be HDMI surely? All we want to test is the cable nothing else.

I understand you want to use a computer's hard disk, but the reason a computer's hard disk returns the same data every time is down to similar transport protocols that ensure you always get the same data, such as the ones used when you download something from the internet - error correction is inherently built into these protocols to ensure data is always correct. Hard disks are not infallible and you'll get read errors from them just as you will from CDs, DVDs or Blu-Rays (though they are admittedly a lot less error prone for obvious reasons). These protocols ensure that any errors are corrected, if necessary by reading a hard disk again.

As well as this, as the_lhc has said, computers don't communicate with each other over HDMI cables. And HDMI is not a computer transport protocol (like TCP/IP is for example, which is the main transport protocol used by computers over networks at this point in time). HDMI is an interface created specifically for transmitting audio and visual data. So the major issues of setting up your test still stand I'm afraid.

 

[Alantiggger]

lol, the cheap cable (hdmi) allows the transfer of data in 1's and 0's as well as a more expensive one..... like the speaker cable argument ... if the buyer can 'hear/see a difference''

then it's up to them .... I think the companies making the cables 'pander' to the guys who have money to burn .... cheap speaker cable transfers sound equally as well as an expensive wire ...fact ... try it.

 

[grdunn123]

After the original post and many responses I'm not convinced that there is any 'real' difference between these cables. There are many comparisons which can be drawn about the price differentials and whether any perceived degradation of picture/sound quality is discernable.

If a pair of £100 Nike trainers last the same as a £10 pair of no-name trainers, both are comfortable and fit well with little in the way of any differences - how many of you would still go for the Nike brand if they could afford them and why?? Is it pure coincidence that many of the more expensive HDMI cables have garish colours and big chunky plugs??

 

[Alantiggger]

Mmmm don't know about the trainers... Mine cost £60.00 (one's i'm wearing just now) and are way more comfortable than a £20.00 pair I had ... the difference here is to do with 1's and 0's and how a cable transfers the data ....

I have used both cheap and more expensive (thinking I was going to get a better picture ... this was not the case though

I wasted money.

 

[grdunn123]

Alantiggger:
Mmmm don't know about the trainers... Mine cost £60.00 (one's i'm wearing just now) and are way more comfortable than a £20.00 pair I had ... the difference here is to do with 1's and 0's and how a cable transfers the data ....

I have used both cheap and more expensive (thinking I was going to get a better picture ... this was not the case though

I wasted money.

I thing you're wrong! Trainers are nothing more than rubber and trim and yet there is still a massive price differential. Have you ever considered that the data that these cables transfer may well be already corrupted by either the software or hardware prior to or post transfer?? Who says that one Sony Blu ray player is EXACTLY the same as another or that one Pioneer Receiver is an exact relica of another....the quality control edicts placed by an individual company may mean that the signal received by or processed after the HDMI transfer may be responsible for the corruption.

 

[professorhat]

Alantiggger:I have used both cheap and more expensive (thinking I was going to get a better picture ... this was not the case though

I wasted money.

Shame you didn't buy from a retailer offering a money back guarantee (as I always advise here). Certainly the simplest way to ensure that, if you can't detect any differences, you don't end up out of pocket.

 

[aliEnRIK]

maxflinn:i think the subject of blind testing has been exausted on this forum, we are all aware that a very large majority of blind tests of hdmi cables find no significant differences..
the crux of my op was whether or not data loss is random, and the consequences..

if we can find that out then we can dig deeper, i agree, discussing blind tests is going off track..

edit.. i don't think it's fair to suggest idc is making up rules to suit his answer rik..

If were to use blind testing to test hdmi cables, then we must use blind testing to test everything

Ive never seen a blind test of amps that have weilded anything different to hdmi blind tests (once the frequency response has been evened up. And if anyone claims the 'only' difference in amps is the frequency response then we should all go out and buy the cheapest decent amp we can and add a graphics equaliser)

Ive never seen blind tests of cd players to conclusively say theyre different

So if were to rely on blind tests for hdmi cables, we must say that neither hdmi cables, cd players nor amps are any different to one another

If you disagree then you dont understand the point of blind testing

 

[aliEnRIK]

maxflinn:rik, do you have any views on whether or not data loss is random?
and if you believe it is not, then i'd love to hear your views on how it is prioritised?

ta...

Data loss is generally random

I say generally as when the hdmi reaches its cliff edge then you 'sometimes' get actual patterns emerging (probably due to entire sections of the picture being lost). Sparklies are entirely random the way they show up.

Id have to recheck, but as I understand it, its quite possible to get a colour slightly wrong with the error correction process, but very difficult to get it entirely wrong (A sparklie). Its not true error correction, its a way of trying to reduce errors.

Further to that, there are limits to the error correction, at that point you get pure errors

 

[Anonymous]

yea i figured it was random rik, and unless anyone has any information to the contrary, then i stand by my initial conclusions.

a working hdmi cable will do it's job, and one that is deemed inferior to another in all likelyhood isn't..

if it was..... i won't repeat myself..

 

[idc]

aliEnRIK:maxflinn:i think the subject of blind testing has been exausted on this forum, we are all aware that a very large majority of blind tests of hdmi cables find no significant differences..

the crux of my op was whether or not data loss is random, and the consequences..

if we can find that out then we can dig deeper, i agree, discussing blind tests is going off track..

edit.. i don't think it's fair to suggest idc is making up rules to suit his answer rik..

If were to use blind testing to test hdmi cables, then we must use blind testing to test everything

Ive never seen a blind test of amps that have weilded anything different to hdmi blind tests (once the frequency response has been evened up. And if anyone claims the 'only' difference in amps is the frequency response then we should all go out and buy the cheapest decent amp we can and add a graphics equaliser)

Ive never seen blind tests of cd players to conclusively say theyre different

So if were to rely on blind tests for hdmi cables, we must say that neither hdmi cables, cd players nor amps are any different to one another

If you disagree then you dont understand the point of blind testing

There is one famous blind test of amps which were equalised and then no one could tell the difference. But that seems an odd test because if you make different things equal, you should not be too puzzled as to why people cannot tell the difference any more.

There are blind tests of CDPs, bit rates, amps and in particular speakers which have been positive, as in people can reliably tell the difference. However, they often do not get much publicity as regularly cheap beats expensive. Indeed in a Hifi magazine I was given recently (it came free with a Rock music magazine) a Cambridge CD/SACD player costing £400 won over rivals which cost from £750 to £1300. That was in a review that included blind testing.

 

[aliEnRIK]

idc:
There is one famous blind test of amps which were equalised and then no one could tell the difference. But that seems an odd test because if you make different things equal, you should not be too puzzled as to why people cannot tell the difference any more.

If an amp is better it would have more detail yes? Everything would sound more natural and 'as it should' etc.

idc:
There are blind tests of CDPs, bit rates, amps and in particular speakers which have been positive, as in people can reliably tell the difference. However, they often do not get much publicity as regularly cheap beats expensive. Indeed in a Hifi magazine I was given recently (it came free with a Rock music magazine) a Cambridge CD/SACD player costing £400 won over rivals which cost from £750 to £1300. That was in a review that included blind testing.

I'll repeat, I personally havnt seen anything CONCLUSIVE to say one cd player is better than another with blind testing. If you recall you read on another forum where the cable believers got 100% right and the sceptics did no better than pure guessing. YOU said your not allowing that as it was one test. If your allowing the cd player, you HAVE to allow that forums cable test too

 

[aliEnRIK]

maxflinn:
yea i figured it was random rik, and unless anyone has any information to the contrary, then i stand by my initial conclusions.

a working hdmi cable will do it's job, and one that is deemed inferior to another in all likelyhood isn't..

if it was..... i won't repeat myself..

You make no sense.

But then I dont think you ever have..............

 

[Anonymous]

aliEnRIK:maxflinn:
yea i figured it was random rik, and unless anyone has any information to the contrary, then i stand by my initial conclusions.

a working hdmi cable will do it's job, and one that is deemed inferior to another in all likelyhood isn't..

if it was..... i won't repeat myself..

You make no sense.

But then I dont think you ever have..............

really? a few people have said that they've found my observations here interesting rik, it's just my own logic, and it certainly makes sense to me..

but lets not get personal huh? because i have a feeling this thread will be history, and that would be a real shame. thanks rik

 

[aliEnRIK]

Perhaps you misunderstood what I meant by random?

 

[Anonymous]

aliEnRIK:Perhaps you misunderstood what I meant by random?
perhaps.. please fill me in?

 

[Anonymous]

the_lhc:Yes but there is currently no way of using an HDMI cable to transfer data between two PCs, it's a display connection, you'd need to come up with an entirely new set of protocols to allow them to talk to each other.

Now whilst it may be beyond you and me in terms of time and money, hdmi output and capture is available on PCs via graphics cards. Google will help here. So I still do not see a technical problem. Send data across the interface and capture it the other end.

 

[professorhat]

Mr Mellie:
the_lhc:Yes but there is currently no way of using an HDMI cable to transfer data between two PCs, it's a display connection, you'd need to come up with an entirely new set of protocols to allow them to talk to each other.

Now whilst it may be beyond you and me in terms of time and money, hdmi output and capture is available on PCs via graphics cards. Google will help here. So I still do not see a technical problem. Send data across the interface and capture it the other end.

Ahh, but then you'd have to circumvent the HDCP protection. Which is of course illegal.

 

[Anonymous]

maxflinn:Mr Mellie:maxflinn:
for me the question that i'd love answered is how a supposedly inferior cable (in comparison to one deemed better) can seemingly lose data but not image consistency? if said data loss is significant enough to be noticed (remember, it's a supposedly inferior cable), and data loss is random, image consistency would be random, and noticed, to the same degree, imo..

if data loss is not random, i'd love someone to explain how or what, enables prioritisation of high value data whilst seemingly discarding data of a lesser value? as i assume would be neccessary to get a consistent picture, albeit one of lesser quality..

ta..

Getting back to the original question then, as I see it there are two types of corruption: 1s and 0s get transposed or data getting lost.

Either way I can not see this as deterministic, i.e. the same input gives the same output, after all this is what computer programs do not dodgy cables.

hi mr mellie.. i cant say i fully get your point.

anyways, the way i see it is this..

if a cable cannot send all the data at the required speed, and data loss is random, and this is noticeable to people in the sense that they can see visible on screen degradation of picture quality (however small) in a given movie scene, compared to a cable that does not lose data, then by the same token, they should be able, on repeat viewings of said movie scene, to also see the manifestations of the random data loss in the different ways it would have to appear..

however, if data loss is not random........

I think we agree with the random bit. Terms like degradation of course are in the eyes of the beholder. The data corruption could I guess do something like sharpen or lessen contrast then it is up to the viewer to judge whether better or not.

If it is non random then the picture/sound would be the same every time for a given data source. If behave differently I suspect we would get terms like 'warm', 'open', 'attack' used for them lol. I just can not see it not being random though.

Unless someone builds something to test cables un-subjectively I think this thread will end without any definitive answers when everyone runs out of steam.

 

[professorhat]

Mr Mellie:Unless someone builds something to test cables un-subjectively I think this thread will end without any definitive answers when everyone runs out of steam.

That would make a change...