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HDMI Cable Question ? Read This First

  • 31-03-2010 6:55pm
    #1
    DERICKOO
    Registered Users Posts: 593 ✭✭✭


    Mod Comment:

    This thread has been "stickied" on request, it contains lots of well informed technical information about HDMI cables and is well worth reading.

    Thanks,

    Ritz



    The following is the original post which started the thread:






    Title: Why you should never pay more than €10 for a hdmi cable

    iv been had.:mad:

    http://lifehacker.com/5506219/why-you-should-never-pay-more-than-10-for-hdmi-cables
    You've probably guessed that gold-plated cables for your home theater are entirely unnecessary. Still, there must be some small quality difference for all that price, right?gas-pressurized, terribly overpriced cables you'll find lining the shelves at electronics retailers. there is no difference that you can see with your eyes between at €6 HDMI cable and a €250 HDMI cable. Here's their full take::eek:


«1

Comments

  • #2
    Idleater
    Registered Users Posts: 6,236 ✭✭✭Idleater


    wow, someone posts on a blog something against Monster cables (Shock - horror :)), so you infer a generic never spend more than €10 on a hdmi cable?

    And to convey this post, you quote the entire first paragraph from said blog without adding your own opinion.

    well done. Internet ++


    There are plenty of reasons why the little technologies that you (they) deride can aid signal transfer under certain circumstances. There are also plenty of companies out there that are making a lot of money on inflating the need for these techologies.
    Consumers should inform themselves or else not blame anyone but themselves if they get "Had".


  • #3
    viperirl
    Registered Users Posts: 316 ✭✭viperirl


    I see that Chord Company who sell some expensive cables have come up with an 'active' HDMI cable. Now active HDMI cables can make sense over 15meters but Chord's fit the active chip into their 1.5metre HDMI cable! How they get away with it is beyond belief. The HDMI spec specifies that the receiver chip in your TV/proj/etc should have an equaliser chip anyway. No need for one in the cable unless its extremely long.
    Of course certain mags will wet themselves over this technology.


  • #4
    The Ritz
    Moderators, Technology & Internet Moderators, RicherSounds.ie Moderator Posts: 2,505 Mod ✭✭✭✭The Ritz


    I'm happy to point folks to the Cable Question Stickey here: http://www.boards.ie/vbulletin/showthread.php?t=2055814993.

    I had resolved to lock all "Cable" threads to avoid the usual shouting matches, but am leaving this one open for now as an experiment :eek:.

    If your science tells you what to believe by all means believe and follow. If your ears tell you what to believe by all means do the same. But for heaven's sake don't use this forum to try to start a row with one side or the other for their beliefs and do not bait/troll/abuse or otherwise cause disruption.


    Thanks,


    Ritz.


  • #5
    DERICKOO
    Registered Users Posts: 593 ✭✭✭DERICKOO


    we are all for you mate head it on, all I did was but my members of boards forums in the light. :)

    http://www.boards.ie/vbulletin/showthread.php?t=2055814993


  • #6
    Idleater
    Registered Users Posts: 6,236 ✭✭✭Idleater


    DERICKOO wrote: »
    all I did was but my members of boards forums in the light. :)
    really? highlighted your ignorance more like.
    Although no maximum length for an HDMI cable is specified, signal attenuation—dependent on the cable's construction quality and conducting materials—limits usable lengths in practice.

    Never is a long time.


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  • #7
    viperirl
    Registered Users Posts: 316 ✭✭viperirl


    Hi Ritz,

    While I agree with you that cable arguments specifically speaker & interconnects generally end up going nowhere I think HDMI cabling is a unique case.
    Due to the nature of the HDMI protocol, it either works or it doesnt, as many know already. There are no variances in between and it has been proven beyond doubt. It's as straight forward as the light switch on the wall. Its either on or off, it works or it doesnt. (no smart comments on dimmer switches please!)
    The argument that 'digital is digital' is not really accurate in the case of HDMI. I won't go into the technical mumbo jumbo but in laymans terms the digital bits are transmitted in real time and ALL of them must be received for you to get a picture. Other digital interfaces such as Ethernet or USB are allowed to drop bits but they have error correction or the ability to retransmit the same packet so you kinda dont really notice unless the drop outs are big. HDMI has no such error correction or the abilty to retransmit lost or corrupted bits so as soon as you start dropping bits the protocol falls over and you get sparkles, frame sync issues or black outs on your screen. As long as you have a cable that can handle the required bandwidth over the desired length, that's all you need.

    I think one of the main concerns about HDMI is that certain mags continue to mislead the public about their 'tests' citing differences between HDMI cables. Those differences are impossible. You cannot contest these findings either on their forums as it results in the thread being deleted and sometimes a ban too. That says it all really. Some High Street stores are culprits too.
    Most independent AV forums have stickys about HDMI and there is little debate over the cabling issue. The conclusion is the same everywhere whereas the debates on analogue cables continue to rage on. Perhaps such a sticky would be useful here Ritz? I have worked in HDMI chip design for many years and I'd be willing to put together something like this and I'd keep it simple and to the point.

    I'm all up for a proper discussion on anything hifi/AV/cable releated but if the thread discends into like 'cables make a difference, no they dont, yes they do, you're an idiot, no you are, etc etc' then obviously it's pointless and should be closed.

    Any thoughts anyone?


  • #8
    The Ritz
    Moderators, Technology & Internet Moderators, RicherSounds.ie Moderator Posts: 2,505 Mod ✭✭✭✭The Ritz


    viperirl,

    I agree that HDMI is a separate case for the reasons you set out here and on reflection was a bit careless with my "science vs. ears" comment, that is more relevant to the analogue side of the house.
    Most independent AV forums have stickys about HDMI and there is little debate over the cabling issue. The conclusion is the same everywhere whereas the debates on analogue cables continue to rage on. Perhaps such a sticky would be useful here Ritz? I have worked in HDMI chip design for many years and I'd be willing to put together something like this and I'd keep it simple and to the point.

    Thanks, that's a very welcome offer, write it up and we'll stickey it.

    Cheers,

    Ritz.


  • #9
    Ricky-Ricardo
    Closed Accounts Posts: 15 ✭Ricky-Ricardo


    viperirl wrote: »
    Due to the nature of the HDMI protocol, it either works or it doesnt, as many know already. There are no variances in between and it has been proven beyond doubt. It's as straight forward as the light switch on the wall. Its either on or off, it works or it doesnt. (no smart comments on dimmer switches please!)
    The argument that 'digital is digital' is not really accurate in the case of HDMI. I won't go into the technical mumbo jumbo but in laymans terms the digital bits are transmitted in real time and ALL of them must be received for you to get a picture. Other digital interfaces such as Ethernet or USB are allowed to drop bits but they have error correction or the ability to retransmit the same packet so you kinda dont really notice unless the drop outs are big.

    I’m no expert on HDMI so I won’t pretend my opinion is in any way definitive but it seems to me that HDMI and standard digital audio interfaces (coaxial and balanced XLR) have some similarities since they do not feature any error correction. In such cases it may be less of an issue as to whether or not they are a worthwhile investment because they do not corrupt data but rather if they offer some level of improved performance over cheap HDMI cables. It does seem that digital audio interconnects improve sound quality somewhat although differences may be less acute than with analogue cables. Of course sound and video are not the same. So if there is some possible variance in performance above the question of data corruption, it would then be an issue as to whether or not the detailing on good quality screens would be sufficient to observe any or much noticeable improvement to justify the cost of more expensive HDMI cables.


  • #10
    viperirl
    Registered Users Posts: 316 ✭✭viperirl


    Ricky-Ricardo wrote: »
    it seems to me that HDMI and standard digital audio interfaces have some similarities since they do not feature any error correction.

    Whereas both of them do not offer any error correction that is where the similarities end. Remember that the audio/video bits being transmitted over HDMI is encypted also and a decryption process needs to take place before the video frame/audio buffers are constructed. This entire process has to take place in the receivers chip domain so in effect the video and audio here is being regenerated after the decryption/equalisation. If ALL the bits were received, the frames can be built without error, otherwise they will not. There is no in between. Which goes back to the same tired old advice on HDMI cables. Once one is capable of passing all bits, no further expenditure on a HDMI can yield better results.


    Other audio interfaces such as SPDIF(typically are transmitted over optical or coax) are a bit different. They key thing to note here is that typically the clock transmitted along the cable for SPDIF is usually used to drive the DAC in the receiving end. Jitter, a common and unavoidable artifact of digital clocks will therefore be also passed straight into the DAC causing modulations on the DAC's analogue outputs. Therefore a SPDIF cable that can prevent additional jitter on the stream may indeed be advantageous. Its less of an issue these days as DAC designs have gotten very clever over recent years in their ability to be more immune from the effects of jitter.


  • #11
    Ricky-Ricardo
    Closed Accounts Posts: 15 ✭Ricky-Ricardo


    There have been jitter reducing signal regeneration circuits in DACs too so I’m not sure how much the decryption/regeneration process would rule out any improvement in performance from a cable. Differences on sound quality have been observed in digital audio interconnects where the clock of the DAC is fed back into the transport in order to control it and so minimise jitter, such as in the old DPA transports and DACs.

    Disregarding the jitter issue, some people don’t believe CD transports have sound characteristics. From my own experience there is a sonic difference between them. Although I note the points about the differing decryption/regeneration process with HDMI, I suppose in a way this argument goes back to the 0’s and 1’s argument – i.e. if all the bits are there no variation in sound quality (or video quality) should occur. I don’t know much about this HDMI stuff but it sounds a bit like that IMHO.


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  • #12
    DERICKOO
    Registered Users Posts: 593 ✭✭✭DERICKOO


    nereid wrote: »
    really? highlighted your ignorance more like.



    Never is a long time.

    yes ignorant in knowing that i have been had on a number of occasions paying inflated prices for a product that pro-ports to do a superior job sorry can not see where you are coming from.

    ah but maybe you have a reason why we should pay inflated prices who knows.:confused:


  • #13
    akaSol
    Registered Users Posts: 717 ✭✭✭akaSol


    I have stated in the past , HDMI cables are by and large what you make of them. Either they are cheap "how cool it looks" , mid range "they do the job" and "you paid what for them!!" kind.
    During my ramblings I have found Hdmi cables that claim to be "1080p" do delver that 1080p but only to 2Gbit/s (Picture and sound) so in that sense HDMI is just HDMI.
    However.
    I buy music from 2l.no. , these cables have FAILED for me. As a result I have purchased a graduating price tag on HDMI with what I feel are increasing results.

    MY Conclusion?
    The €10-€20 will work fine on any 1080p panel, blu-ray or otherwise. But forget 3D-1080p, forget DTSMA (fidelity tracks).

    >Sol


  • #14
    akaSol
    Registered Users Posts: 717 ✭✭✭akaSol


    I have stated in the past , HDMI cables are by and large what you make of them. Either they are cheap "how cool it looks" , mid range "they do the job" and "you paid what for them!!" kind.
    During my ramblings I have found Hdmi cables that claim to be "1080p" do delver that 1080p but only to 2Gbit/s (Picture and sound) so in that sense HDMI is just HDMI.
    However.
    I buy music from 2l.no. , these cables have FAILED for me. As a result I have purchased a graduating price tag on HDMI with what I feel are increasing results.

    MY Conclusion?
    The €10-€20 will work fine on any 1080p panel, blu-ray or otherwise. But forget 3D-1080p, forget DTSMA (fidelity tracks).

    >Sol


  • #15
    Idleater
    Registered Users Posts: 6,236 ✭✭✭Idleater


    DERICKOO wrote: »
    ah but maybe you have a reason why we should pay inflated prices who knows.:confused:

    Did you even read what attenuation is, and how it affects signal transfer. I was merely pointing out to you that your "argument" is based loosely on what other people have told you, not your own experience, nor do you bring anything to the table in form of support for your argument, other than saying that other people are wrong.

    For what its worth I tried this cable (because I wanted to get the ps3 up and running while I waited for this to arrive). According to your logic it should have worked but didn't.

    That is along a .7m cable. Your sole big statement is "never spend more than €10 on a cable" which in light of what many other posters here have highlighted for several reasons other than marketing speak is downright incorrect.

    I have no problem getting into a nice technical discussion about gased copper shielding and power transfer, even the how LPCM over HDMI requires better cables than DTSMA, but I'm going to guess that it would be a fraction over your head. Feel free to prove me wrong though, I like such discussions.


  • #16
    viperirl
    Registered Users Posts: 316 ✭✭viperirl


    Ricky-Ricardo wrote: »
    There have been jitter reducing signal regeneration circuits in DACs too so I’m not sure how much the decryption/regeneration process would rule out any improvement in performance from a cable. Differences on sound quality have been observed in digital audio interconnects where the clock of the DAC is fed back into the transport in order to control it and so minimise jitter, such as in the old DPA transports and DACs.

    I agree with you there. Using the DAC as the master clocking is one way of reducing the jitter issue. You effectively have one clock domain so you dont have the technical hurdles to overcome in the case of SPDIF where you are passing continuous real time data from one clock domain to the other.
    Ricky-Ricardo wrote: »
    Disregarding the jitter issue, some people don’t believe CD transports have sound characteristics. From my own experience there is a sonic difference between them. Although I note the points about the differing decryption/regeneration process with HDMI, I suppose in a way this argument goes back to the 0’s and 1’s argument – i.e. if all the bits are there no variation in sound quality (or video quality) should occur. I don’t know much about this HDMI stuff but it sounds a bit like that IMHO.

    Again, I'd agree with you on CD transports that seem to sound different. Assuming that each transport reads the bits off the CD layer in the exact same fashion(do they I wonder??) I can only conclude that the tranmission circuitry of each have varying amounts of jitter injected onto the output stream and this is reason behind their sonic differences.

    Applying the same reasoning to HDMI is not quite the same though. Another key thing to note that in the case of SPDIF, the audio is sent as continous stream and ususally the receiving circuitry in the DAC is somewhat reliant and "vunerable" to the timing on that incoming stream.
    But with the HDMI, the audio is not a continous stream. It's sent in chunks placed in between video and control packets. There is quite of bit of proccessing to be done on all of this data before it gets passed to the outputs and indeed video or audio DACs in the receiving chip/chipset. Therefore the DACs are far more decoupled from the incoming data on the chip inputs and if the designer is worth his salt, jitter on the HDMI cable should be a non-issue here.


  • #17
    viperirl
    Registered Users Posts: 316 ✭✭viperirl


    akaSol wrote: »
    However. I buy music from 2l.no. , these cables have FAILED for me. As a result I have purchased a graduating price tag on HDMI with what I feel are increasing results.

    Hi Sol,
    What issues did you come across here? Was it case that you found better CD playback with 'better' HDMI cables?


  • #18
    zabzab
    Closed Accounts Posts: 16 ✭zabzab


    I am not one of these people who believe the silver monocrystal or what ever
    that some specialist companies push But i have spent a long time in the audio industry and cheap cable is exactly that. In a direct AB comparison some years ago I wired one side of a huge nightclub system with good speaker cable to replace the 1.5 mains cable that the system was originally wired with
    and left the decision to the owner and managers as in you pick which side sounds better and if not i don`t get paid. All agreed one side was much better and when I switched inputs to make sure that track was having no effect agreement was still the same. When it comes to hdmi cable there are a lot of cheap cables being sold which are not certified by the hdmi assoc.
    When you have spent maybe a thousand euro on a hd set and maybe 200 on a blue ray player does it make sense to join the 2 with the cheapest cable you can find? If you are one of these people who see no difference between a High end panasonic for example and a set for half the price than buy the cheap cable.( and the cheap set ) I was asked to approve the sound of a recent surround sound buy where one front and one back channel had been interchanged and the center was fed the other back ,the owner was thrilled with his system and i kept my mouth shut. How many people have bought a hd set connected it up to an aerial and assumed thay were watching HD because the label on the SET said hd. By the way SKY HD is only 720 so again a cheap cable will do. I had the experience last year where I brought a long 20 mt unbranded hdmi cable to the Monster comparison road show ( not exactly a fan of Monster ) was amazed by the fact that first my cable was tested and shown to be capable of sending 720 over the distance and as the spec was stepped up I could see the detererioation of the signal . They then compared it with a same lentht monster and you could see as the spec was stepped up how the two signals varied. The technician did agree that over a 1 to 2 meter length that most midprice cables matched the monster but after that the difference showed but also as cable aged the heap cable would deterioate
    faster but a bit like someone new driving you car and saying brakes a bit low you didn`t notice


  • #19
    viperirl
    Registered Users Posts: 316 ✭✭viperirl


    zabzab wrote: »
    I had the experience last year where I brought a long 20 mt unbranded hdmi cable to the Monster comparison road show ( not exactly a fan of Monster ) was amazed by the fact that first my cable was tested and shown to be capable of sending 720 over the distance and as the spec was stepped up I could see the detererioation of the signal . They then compared it with a same lentht monster and you could see as the spec was stepped up how the two signals varied. The technician did agree that over a 1 to 2 meter length that most midprice cables matched the monster but after that the difference showed but also as cable aged the heap cable would deterioate
    faster but a bit like someone new driving you car and saying brakes a bit low you didn`t notice

    Yes, the signal quality between two HDMI cables WILL have differences. But due to the fact that its a digital signal, thats irrelevent as long as the voltage level is above the threshold to be '1' or below a certain threshold to be a '0'. As most know, there is no such thing as a better 1 or a better 0 in digital. Its either one or the other. Nothing in between. As I've said before, the HDMI protocol will fail if any bits are lost or corrupted. So the protocol can withstand a significant amount of deterioration WITHOUT loosing a perfect picture until at some point the deterioration causes the protocol to fall over at which point you get sparkles or worse.

    I've been to a few HDMI events in the past and to be honest I'd wary of what Monster cable reps say or appear to demonstrate to me.


  • #20
    cnocbui
    Registered Users Posts: 19,651 ✭✭✭✭cnocbui


    zabzab wrote: »
    When it comes to hdmi cable there are a lot of cheap cables being sold which are not certified by the hdmi assoc.
    When you have spent maybe a thousand euro on a hd set and maybe 200 on a blue ray player does it make sense to join the 2 with the cheapest cable you can find? If you are one of these people who see no difference between a High end panasonic for example and a set for half the price than buy the cheap cable.

    I bought a €7 HDMI cable from Lidl and used it to connect my son's Xbox 360 to our hi-end Panasonic TV. It works perfectly. So yes, it did make sense for me to use the cheapest cable I could find, because it works.

    There is another issue. There is not necessarily a direct relationship between cost and technical quality. Just because something is cheap it does not always follow that it is shoddily manufactured.


  • #21
    andy1249
    Registered Users Posts: 1,338 ✭✭✭andy1249


    Note that this applies to the all digital HDMI interface and HDMI cables only ... I see analog arguments being included above , which have no place here.
    Old World analog arguments do not apply to these cables.

    Why is it impossible for a HDMI cable to be responsible for incremental changes in picture quality ?

    Video information is transmitted as a series of 24-bit pixels - 8 bits each for each of the primary colors; these are encoded using the TMDS protocol into three 10-bit words per pixel clock period (i.e. each pixel is made up of 30bits).

    They are also supplied to the screen at a rate equal too …

    Bandwidth = Resolution x Refresh Rate x [1 + Blanking Period] in Bps

    Where the Blanking Period is the sum of the horizontal and vertical blanking intervals.

    For 1080p @60hz this would be

    1920 x 1080 x 60 x [1 + 0.16] = 144.4MHz or 144.4 million pixels/sec.

    You can work out how many pixels per second for any particular content by substituting resolution figures and hz rates into the equation above , Im picking 1080p @60hz as this is the worst case in terms of content actually possible at the moment.

    Now lets start by assuming a 0% bit error rate on a particular cable.
    That means no errors whatsoever in the stream , meaning all pixel information , that’s 3 x 10 bit words for each pixel gets through as it was transmitted , meaning a perfect result.

    A Cable is a passive collection of wires , there is no way for a cable to manipulate the data in the 3 x 10 bit words , so a cable can in no way improve on the data , so for a cable with 0 bit error rate , this is as good as it can be.

    That means that the only possible way for a cable to change the data is if the cable in some way corrupts the data.

    Now consider what would have to be the nature of this corruption if the cable is somehow to be responsible for “Deeper blacks“, more vibrant colours , and so on.
    The type of thing claimed by some of the more disreputable magazine reviewers and cable sellers !

    The corruption would have to be in the form of a fault which somehow changes the 3 x 10 bit words for each pixel so that they all the pixel information for blacks were changed to a deeper value of black and all the different pixel information for the other colours were changed to more values that encoded for more vibrant colours !

    So you would have to believe that random errors introduced into the bitstream could somehow cause all pixels to encode for values that produced a better picture and that it could do this 144 million times per second.

    Clearly such a thing is beyond any probability, in fact any errors introduced would most likely cause a 3 x 10 bit word pixel value that made no sense or was totally different to the original value , showing nonsense on the screen if indeed it showed anything at all. ( In the vast majority of cases this is exactly what happens on data corruption , the interface just stops working )

    In the case of long cables , there is an attenuation problem , but this again does not affect sound or picture quality because the electrical signal present on the cable is not an analog signal , only the levels representing the data are important , and when these become indistinct you lose data. Meaning in the case of an HDMI cable , which carries so much data , that in all probability the cable just stops working.

    As you can see from this , it is clearly impossible for a HDMI cable to be responsible for incremental picture changes , either the data gets through with a very very low or zero bit error rate, or most of the data gets corrupted , meaning for most cables it really is a case of they work or they don’t.

    You cannot have cables that are slightly better than others in terms of picture quality; the technology simply doesn’t allow it. Its completely impossible.

    Regarding audio quality with HDMI , Audio data is inserted into the video blanking periods , it is not a continuous bitstream , it is recovered and reclocked at the sink ( receiving device ) using a formula based on the Video clock.

    The audio clock is not transmitted over HDMI
    Rather, it is derived at the sink end from the video clock

    The Source computes integers N and CTS such that
    128×fs = fTMDS_CLK×N/CTS

    N is fixed for a given video and audio rate (table lookup)

    Source counts TMDS clocks per audio clock to determine CTS
    N, CTS transmitted in audio clock regeneration packet

    The sink regenerates the audio sample clock from the received fTMDS_CLK, N, and CTS values

    Asynchronous video and audio clocks, or audio clock jitter, can cause CTS to change over time , but its important to realize that such jitter cannot happen due to the
    cable , this can only happen due to problems in either the source or sink silicon/clock combination , so regardless , the cable cannot affect audio quality.

    In addition , you need to note that typical HDMI chipsets , such as the Silicon image 9134/9135 transmitters and receivers , have jitter performance better than 1ps.

    Summing it all up , in the case of a HDMI cable , no amount of spending will improve picture or sound quality , thats impossible. If it works , it works , Thats it !!


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  • #22
    akaSol
    Registered Users Posts: 717 ✭✭✭akaSol


    @viperirl
    I would miss "chunks" of audio data, e.g. some violins would play and not be audible , I would move back the disk and there they where. Some cables just collapsed causing my amp it to reset( much to my horror :eek: ) I have had frame cutting ,the top part was splitting from the middle of my screen as if it was being hit by different images at the same time, mutch like frame loss in a computer game.

    @andy1249;65219746
    Then the 9 brands of "Cost effective" HDMI cables I played with were ALL classed as "one's that just did not work"? But the not so "cost effective" have never had that issue?

    I am not looking for self ratification on my expenditure, also I am aware that ultimately copper is just copper. But sometimes you just want it right with out the issue , then yes I would suggest you spend more.

    >Sol
    (Edit :actually I have found some HDMI cables give a slightly brighter picture and somewhat less artefacts and better edging)


  • #23
    viperirl
    Registered Users Posts: 316 ✭✭viperirl


    akaSol wrote: »
    I have had frame cutting ,the top part was splitting from the middle of my screen as if it was being hit by different images at the same time, mutch like frame loss in a computer game.

    Yes I've seen this before in the lab. It's simply a case of the cable not having the required bandwidth or being just on the edge of that threshold. In other words its considered as a non-working HDMI cable.


  • #24
    andy1249
    Registered Users Posts: 1,338 ✭✭✭andy1249


    Then the 9 brands of "Cost effective" HDMI cables I played with were ALL classed as "one's that just did not work"? But the not so "cost effective" have never had that issue?

    Yes , major dropouts as you describe do fall into the category of not working , but unlike yourself , I find no correlation to cost.
    In any case , dropouts such as this prove to be a small percentage occurance , but are spread across the whole of the pricing spectrum.

    Spending more is no guarantee of eliminating faulty cables.


  • #25
    viperirl
    Registered Users Posts: 316 ✭✭viperirl


    @andy1429
    I posted something similar to your long post above on a certain magazines online forum about a year or more ago. My aim was to try and be informative given my background in HDMI chip design and I had no intention of flaming or baiting anyone.
    I was extremely p*ssed off when after about an hour my thread was deleted and I got IP banned from the site. No warning from mods, nothing of the sort. I was gone!
    Other posters from other AV forums have reported the same.


  • #26
    andy1249
    Registered Users Posts: 1,338 ✭✭✭andy1249


    Yup , I believe I know which magazines site that was , they are known for it , whats even more incredible is the stuff they dont delete and leave there for everyone to see , making themselves look like clueless idiots !

    One thread in particular was about a certain Panasonic TV review and whether or not it had 24p capability , the review said it did , it turns out it didnt , the reviewer was called out on it , and it turns out he didnt even know the specs !!

    Call them out on anything and they wave the ban stick !! Its a joke of a site and a joke of a magazine.
    They persist in these ridiculous HDMI cable reviews , saying things even the manufacturers don't and wouldn't claim for their products.


  • #27
    Ricky-Ricardo
    Closed Accounts Posts: 15 ✭Ricky-Ricardo


    viperirl wrote: »
    I agree with you there. Using the DAC as the master clocking is one way of reducing the jitter issue. You effectively have one clock domain so you dont have the technical hurdles to overcome in the case of SPDIF where you are passing continuous real time data from one clock domain to the other.

    The point here is that differences in digital audio cable quality were often observed as well when master clocking from the DAC to the transport which minimises jitter so I’m not convinced about the argument regarding jitter induced through the transit of the signal through SPDIF (in contrast to HDMI) leading necessarily the significant differences in sound quality.

    [/QUOTE]Again, I'd agree with you on CD transports that seem to sound different. Assuming that each transport reads the bits off the CD layer in the exact same fashion(do they I wonder??) I can only conclude that the tranmission circuitry of each have varying amounts of jitter injected onto the output stream and this is reason behind their sonic differences.[/QUOTE]

    I’m not convinced transport sound quality can solely be attributed to varying levels of jitter. High-end transports like the Teac VRDS and the sought after Philips Pro mechanisms have minimal jitter yet have divergent sound characteristics.

    [/QUOTE]Applying the same reasoning to HDMI is not quite the same though. Another key thing to note that in the case of SPDIF, the audio is sent as continous stream and ususally the receiving circuitry in the DAC is somewhat reliant and "vunerable" to the timing on that incoming stream.
    But with the HDMI, the audio is not a continous stream. It's sent in chunks placed in between video and control packets. There is quite of bit of proccessing to be done on all of this data before it gets passed to the outputs and indeed video or audio DACs in the receiving chip/chipset. Therefore the DACs are far more decoupled from the incoming data on the chip inputs and if the designer is worth his salt, jitter on the HDMI cable should be a non-issue here.[/QUOTE]

    The assertion you made is that HDMI cables either work or don’t – there is nothing in between. Maybe there is something beyond that? You said the signal regeneration and reconstitution of the data differs with common digital audio interfaces. I don’t know a great deal about this technology having limited interest in AV technology but it seems to me that there “may” be some differences between cables that achieve the required level of performance since some forms of regeneration technology have also been utilised in DACs, although obviously not the reconstitution process. For that reason I still think it may be possible that the differences observed may be genuinely perceived at least some of the time. If this is the case then nonetheless it may not be worthwhile investing a lot of money in cables as visual acuity may be insufficient to appreciate the sort of differences commonly appreciated in the hi-fi arena.


  • #28
    kierank01
    Registered Users Posts: 720 ✭✭✭kierank01


    I was in a shop a couple of months ago, and they had 2 hdmi cables.
    One was for €15 and the other was for €25, both were rated for 10.2G/s

    Now I don't know much about hd stuff, but I know that digital is digital, so I asked what what the difference was, and no one could give me a satisfactory explaination. They were talking about getting a better picture from the expensive one, which I could'nt understand, as if they were both rated for the same bit rate, how could the cheap one send less information?

    This thread has shed some light on this though, as I didn't know that there was no error correction in hdmi, so a more higher quality cable can potentially operate in harsher conditions than a cable with one with less shielding.

    So if a low quality cable works in a particular environment, there is no case for spending more money, unless you need to be able to introduce more interference, or move to a harsher environment.


  • #29
    akaSol
    Registered Users Posts: 717 ✭✭✭akaSol


    A quick notary point did not have the audio timing issues when connecting my BRP via its analogue out.

    Removing the HDMI competency , surely then it was a result of the HDMI processor on the AV AMP not being able to cope with its "decoding"
    Why does then does that work with different cables while the "cheap" cables passed through the picture when connected straight to my panel, all be it stereo. The cable works but not when putting it thru a €400+ av amp , so therefore its only half inferior ???

    >Sol

    @Ricky-Ricardo
    I detest listening to an Audio Cd with hdmi. I much rather RCA's.


  • #30
    andy1249
    Registered Users Posts: 1,338 ✭✭✭andy1249


    The cable works but not when putting it thru a €400+ av amp , so therefore its only half inferior ???

    This comes up a lot , various amps not working in what looks to be a cable fault situation , but its not the cable its the amp , some amps have weak or lower voltage level outputs or less sensitive inputs , meaning a cleaner or stronger signal is needed for proper operation , likewise , this happens with some projectors and TV's too.

    The cable itself is usually not the root cause here , rather a lack of robustness in the devices firmware or hardware design. Indeed , without naming any names , some brands are known for it. In line boosters or active switches can usually solve the problem.


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  • #31
    akaSol
    Registered Users Posts: 717 ✭✭✭akaSol


    andy1249 wrote: »
    Rather a lack of robustness in the devices firmware or hardware design. Indeed , without naming any names , some brands are known for it. In line boosters or active switches can usually solve the problem.
    How about an RXV3900?


This discussion has been closed.
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