• What Is HD?

    What is HD? What is high resolution? In the video world most people will say 720p, 1080i, and 1080p. They don't consider compression or the original format of a video. When it comes to music the term HD is tossed around very loosely and can include anything that's not MP3. The definition of HD is incredibly elusive. Do the letters even stand for something? One can say HD stands for High definition. However when the letters HD are used on a binocular lens coating, an automotive paint additive, and a wall-mount clay extruder all bets are off. The diluere of the letters HD continues. I'm willing to bet we'll see some 3D audio downloads if the past is any predictor of the future. AIX and iTrax President Mark Waldrep has a very clear idea of what constitutes HD and high resolution audio & video. In the following linked podcast Mark even mentions Sonic Studio's Amarra and the large role music servers will play in the future of high end audio.



     

     

    Mark was recently interviewed by Home Theater Geek's Scott Wilkinson about high definition and surround music. The interview was published as an episode of Scott's weekly podcast for Leo Laporte's TWiT podcasting network. I highly recommend everyone download the MP3 or listen online to this very interesting interview.

    Follow this link to download the MP3 or listen online

     

     

     

     

    Additional Links

     
    iTrax       iTrax

     

     


     

     
    Comments 17 Comments
    1. audiozorro's Avatar
      audiozorro -
      There is a thread already on this interview in the Vinyl Asylum as provided here:<br />
      <br />
      http://www.audioasylum.com/audio/vinyl/messages/88/886806.html<br />
      <br />
      I would take exception with anyone who might say that the excellent analog studio masters, whether tape or direct-to-disc, are inferior audio to digital.<br />
      <br />
      I do think very highly of the AIX records which are recorded at 24/96 and I'll praise any label that releases their studio masters in the original recording format. I only wish AIX would release their records as data discs, similar to Reference Recordings, in addition to DVD-As or Blu-ray discs. I have several AIX DVD-As that I ripped, though two discs could not be ripped and on one only some of the tracks could be ripped. That's a hassle I could do without so I stopped buying AIX DVD-As but I would certainly buy many more if AIX released their studio masters on data discs. I may buy some of their 24/96 downloads from iTrax but large file downloads take too long for me and I like the physical disc as a lifetime backup.<br />
      <br />
      It funny that most audiophiles, as do I, would consider SACD to be hi-rez or HD. Here's what Reference Recordings has to say:<br />
      <br />
      [Quote]<br />
      Why did Reference Recordings decide to make SACD after all?<br />
      <br />
      We know, many have wondered what took us so long. Many feel that SACD is an improvement over Compact Discs, and it still has a large following among audiophiles worldwide.<br />
      <br />
      RR has a virtually unbroken history of making the finest possible high resolution recordings. We started with analog tape. We were not satisfied with early technology, 16 bit digital recordings, but soon began making HDCD (High Definition Compatible Digital) recordings, in which the process was co-designed by our own recording guru Keith O. Johnson. In the opinion of many, these are probably the best digital recordings ever. Currently we record at 176.4 kHz/ 24 bits, with HDCD. RR’s master recordings are made using PCM, not the DSD which is the native format for SACD. For a long time, we weren’t satisfied with the sonic results of the conversion of PCM to DSD and so we did not make SACDs. New technological improvements now make that conversion much less of an issue. We’re excited to be making SACDs for fans of the format. Our first two releases are Two-Channel Hybrids, but we plan Surround-Sound SACD for the near future!<br />
      [Quote]<br />
      <br />
      Thus for instance you have a choice of a $23 SACD of the Exotic Dances from the Opera or the studio master format HRx format at $45.<br />
      <br />
      I agree with Mark Waldrep on some counts such as I place live music at the top of the food chain. The studio master would be next and since that is what AIX is releasing, his stuff is great. In my book downsampled or upsampled releases do not sound as good as the studio masters and usually never will regardless whether the release is HD or not. I also feel that multi-channel audio can sound better than stereo, however money and space are the usual impediments.<br />
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hi Zorro - Thanks for leaving the comments. This is a very important discussion that I hope more people join. I had an extensive conversation about Mark's comments with a colleague on mine yesterday. <br />
      <br />
      For people who haven't listened yet: I believe Mark is using objective data to determine what real high definition or high resolution means. A certain dynamic range and sampling frequency must be present from the beginning. He states that analog masters don't have the dynamic range of a digital capture so they can never be high definition. <br />
      <br />
      Right now I don't agree or disagree with Mark. I've been thinking we need a classification for material that began as analog and was converted to high bit rate high sampling rate digital. I have many files that started as analog tape and are now 24/96, 24/176.4, or 24/192 digital files. The sound is spectacular.<br />
      <br />
      This one really has me thinking :~) I'm glad Mark raises his points in the interview.
    1. barrows's Avatar
      barrows -
      not had time to listen to Mark's comments, but I will say I certainly respect his work. I have some 24/96 downlods from Itrax (Firebird/Bolero is one) and they sound very, very good-although his preference for chamber music recording is a touch dry for my tastes (I do know that he prefers it this way, and it is purposeful).<br />
      My comments are preliminary: I would class HD as anything that is above 16/44.1, with the caveat that these cannot be just upsampled from lower resolution sources. I would disagree that analog tape is not high resolution though-what is the true dynamic range of 1" tape running at 32 ips with the best nr today? 24 bit digital can exceed 120 dB of dynamic range-but I challenge anyone to have an audio system that can actually exceed 120 dB. It seems to me that the advantage of high resolution (beyond 16 bit) is not really the increased dynamic range, but may be more related to the relaxation of the requirements of the digital filters, and better microdynamics and transient fidelity.<br />
      Anyone who has heard really good vinyl playback (which is really limited dynamically) notes that vinyl does have some advantages over 16 bit digital in terms of microdynamic expression, some of the best recordings I have heard have been digital re-masters of older 1960s analog tapes. Even now, some engineers record on analog tape, and then transfer to digital to get a certain sound (I believe that "Raising Sand" was done this way, and is available as a 24/96 download from HDtracks).<br />
      In any case, this is an interesting discussion...
    1. PeterSt's Avatar
      PeterSt -
      Hi Chris,<br />
      <br />
      Personally I don't see why one would want to make a subject out of this;<br />
      As you may know I'm into words and definitions (and homonyms, synonyms etc.) quite a bit, and on my part something like "HD" for music does not exist. And *if* it does, it should be about HDCD, because "they were first" so it set the definition for it.<br />
      <br />
      The fact that some instances throw it to us, only tells me that they don't know what they talk about *or* are trying to fool us. Or is it a coincidence that some name redbook "HD" (for downloads) where "highres" clearly doesn't suffice ?<br />
      <br />
      If I had to say it (just by looking at the world around me), highres (haha) audio material is named highres, and not high definition.<br />
      Similarly HD is for video (movie) material.<br />
      <br />
      It is always interesting to look at the opposite of definitions. So, the opposite of HD is clearly SD. Well, I personally never heard of redbook being called SD, or ? This alone unjustifies HD for audio, just because the opposite of is is accepted as SD (which is for video).<br />
      <br />
      Indeed it is interesting to notice that SD as well as HD for video is unrelated to the format being lossy (!) compressed or not. So, even HD is lossly compressed. Not so with audio, where highres never would be lossy. It just doesn't exist.<br />
      <br />
      For fun we could go down to the merits of things, for example noticing that MP3 is just redbook, but lossy compressed. Because remember, it is still 16 bits and 44K1 when it is played.<br />
      Now, would we call the opposite of highres, lowres ? No, not that I know of. But *if* we'd do that, we'd clearly be referring to MP3 and the like, because net the 16 bits won't be utilized anymore. Funnily enough this is now about the bit depth, while the sample rate is still 44K1. So, what actually is highres ? does it need a higher bit rate to be justified ? does it need a higher sample rate ? Well, I tried to explain elsewhere that both have a relation, and neither can do without the other (read : a higher sample rate without a higher bit rate is useless). Ok, so highres needs both. But hmm ... this unjustifies MP3 as lowres, because there only one of the phenomena is lowered (the bit depth). No wrong, because one of the dimensions is sufficient to lower the resolution. Ah ... ehh ...<br />
      <br />
      To make the mess complete ... overhere we call HD only HD when it can do 1080p (debateable by itself because 1080i will never be transmitted through air anyway, 1080 clearly being HD because how to call it otherwise when 720 just is not). This, while over at your place (at least some years ago) 720p was sufficient to be named HD. Here we call that "HD ready", don't ask me why.<br />
      Btw, anyone ever saw 720i ?<br />
      <br />
      To finish it all of ... if I can clearly see one thing from a movie, it is its resolution. Btw, this is a rather physical phenomenon, because you can just count the pixels and you'd know. This would call for denoting movies by means of resolution, hence highres etc.;<br />
      For audio I don't recall much that my brains think in hearing/perceiving resolution, although this is a matter of getting used to, and maybe today I can and do. But how many decades do we express about "definition" in audio ? I must admit I don't like this phenomenon much, because it is a vague thing, and I guess today we merely talk about separation. Of course we won't introduce "highsep" because it can be incurred by many other things than resolution itself.<br />
      <br />
      Ok, contestant #3 doesn't know the answer.
    1. ted_b's Avatar
      ted_b -
      I am very pleased that Mark chose to define HD (in audio) as specific as he did. It had lots of logic behind it, had clearly defined borders, and frankly took a refreshing approach...from the standpoint of human hearing. He surmised that unless audio is sourced from a format that allows for 144 db of theoretical dynamic range, and that the parameters are kept intact throughout, it ain't HD. You can argue with him (except for the live musicians thing), but it's a definition that has terms and conditions that are arguable. I like that. I also like his insistence that we have a standardized nutrition label (my term, not his) that clearly shows what steps the original source has taken during the process (like the old AAD, DDD stuff we saw on cd's).<br />
      <br />
      I'm not learned enough to understand whether his comments about vinyl and analog tape are accurate, but given his definitions, it would be easy enough to confirm/deny and debate.<br />
      <br />
      I sent Mark an email after hearing the interview, mentioning how much i appreciate his support of hirez surround, etc. I also asked him about my ITU setup (5.1 portion of my HT/music room). He sent an email back, was helfpul, informative and appreciative. Seems like a good guy, with an obvious agenda...improving the source material and creating more momentum for HD surround. Should help us all, 2 channel or otherwise.
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      Hi Peter - You certainly lost me after the first sentence, but I can offer an answer as to why, <i>"[O]ne would want to make a subject out of this."</i><br />
      <br />
      A simple reason is so the consumer know what he is purchasing. If Filet Mignon defines a certain cut of meat I don't think people would be happy to receive a lump of ground hamburger with the Filet Mignon label that looks like Filet Mignon. Definitions and clarity are always a good thing in my opinion.
    1. barrows's Avatar
      barrows -
      I totally agree, it is really hard to know what one is actually purchasing. Look at DVDAs, it is seriously difficult to know what is really on them until they go into DVDAexplorer. Then there are the high res downloads at 24/96-where did these come from: analog tape, 24/176.4 digital masters, 24/48 masters, or worse?<br />
      I once read something that mentioned an SACD release from Bob Dylan was actually converted to DSD from a vinyl LP, because the original analog mastertapes were too damaged to use! There were also cases of SACDs being released that were just upsampled from 16 or 20 bit digital files.<br />
      It would be really nice for consumers to know what they are buying-the audiophile labels are usually great at disclosing the nature of what they are selling, but the major labels...
    1. aps's Avatar
      aps -
      Thanks for the link. The emphasis on high-quality, multi-channel, music was interesting. I’ve struggled with room acoustics and wonder if multi-channel would provide the solution. So, while the cost and space seems prohibitive, it'd interesting to listen to a good multi-channel set-up. Also, agree that a simple brand, coupled with standard format, is a critical foundation to successful mainstream marketing of high-resolution music.<br />
      <br />
      Regards<br />
      APS
    1. danny71's Avatar
      danny71 -
      Well, I certainly am not young enough to know it all..<br />
      <br />
      Chris, thank you for being on your toes, catching and sharing stuff like this! In my opinion this is highly interesting material and i find the reasoning in the pod cast quite easy to follow.<br />
      <br />
      Unfortunately I don't have the money to invest in a 5.1 setup of the same quality as my 2 channel setup. Some of the limitations are not related to money though, as an example the manufacturer of my carefully selected DAC only provides 2 channel stuff. (Yes, I know.. Some of the examples in the pod cast refers to simple and non expensive installations of 5.1..)<br />
      <br />
      Keep up the good work!
    1. chuckbass's Avatar
      chuckbass -
      A piece of extremely powrful and full-featured <a href="http://www.bluray-rippers.com/index.html">Blu Ray Converter </a> is mainly designed to converter Blu-ray and M2ts files to HD video.<br />
      <br />
      As the professional and multifunctional <a href="http://www.bluray-rippers.com/index.html">Blu Ray Ripper</a> which can rip Blu-ray and DVD movies to all formats that you can enjoy on more players.
    1. Music's Avatar
      Music -
      The <a href="http://english-essay-writing-help.org/index.php">Essay writing help</a> composing is really challenging, nevertheless such professionals as you are can to write the comparison contrast essay easily and fast. Thank you a lot for this!
    1. ted_b's Avatar
      ted_b -
      This is like the third or fourth time this user has done this.
    1. PeterSt's Avatar
      PeterSt -
      I dunno much about english, but me thinks the music man can better start with studying his own essays first.
    1. syganymede's Avatar
      syganymede -
      I suggest a definition of HD.<br />
      <br />
      1 Overhead. Recording at 24bit resolution, with -24dBFS equivalent to analog 0dB levels. Thus giving 24dB overhead. I normally assume that good analog equipment has to have at least 20dB overhead, so this is a good start. Many analog systems do not have anywhere like 20dB overhead - checl out your average power amplifier!<br />
      <br />
      2 Frequency range. Recording at 44.1kHz means that there is no way to get more than about 20kHz signals through the system (the famous Nyquist). But it is widely known that many musical instruments generate audio spectra well above 20kHz, or in other words have dynamic signal rise times much faster than a system with 20kHz bandwidth can handle. So we need more bandwidth. Moving to 96kHz will increase this to 45kHz or so bandwidth, giving us much more chance to reproduce the original sound of musical instruments. Of course higher would be better.<br />
      <br />
      So lets define HD as<br />
      <br />
      - 24bit, with 0dB analog = -24dBFS<br />
      - 96kHz with filters not below 45kHz<br />
      <br />
      Comments?
    1. machinehead's Avatar
      machinehead -
      Actually there is already a quite literal definition, HDCD was created by Pacific Microsonics and now owned by Microsoft:<br />
      <br />
      http://en.wikipedia.org/wiki/High_Definition_Compatible_Digital
    1. machinehead's Avatar
      machinehead -
      What is a "wall-mount clay extruder"?
    1. The Computer Audiophile's Avatar
      The Computer Audiophile -
      wall-mount clay extruder HD<br />
      <br />
      http://www.amaco.com/shop/product-663-brent-clay-extruder-hd.html