See also:

High Resolution Audio, Asynchronous USB, Oversampling, Upsampling and Stuff:

The Current State of Affairs (1)

 

"High resolution" digital audio ¹

This process is progressing actually quite rapidly and, judging by the current sales decrease rate, CD format, which was a major standard for music for more than 20 years, in a couple of next years may practically disappear from the stores in its current physical shape.

Of course, this won't necessarily move so-called "CD format" to history, because the format itself can migrate from physical media to PC based systems. However, at this moment the music in classic CD format (44.1 kHz / 16 bits) can be still purchased mostly only a classic way, as a physical CD, and only sometimes also by downloading. In that way, nothing still has changed about the way the CD is sold, however since internet speeds and local discs capacities are increasing, there is no reason for 44.1/16 not to move to the web stores. Actual media for local storage of downloaded music gets inexpensive, and hundreds of GBytes now can be already purchased for several tens of EUR, with all the convenience in use, as is the one of, say, removable USB hard discs.²

On the hi-res side, physical standard as DVD-A was never a real success, and 96 kHz - 192 kHz / 24 bits files are usually available only for download. At this moment this part of the market is made of dedicated consumers, so they are, it is understood, either ready to buy adequate internet connection, or to accept longer download times.³

As a result, some of us from this side of the business have been lately faced with strong demands to offer up to 192/24 compatible audio devices for PC, and with claims that anything below this is already "obsolete" within high quality audio scope. Indeed, a quantity of material available in hi-res formats is increasing. The most important, some classic recording companies partially accepted hi-res challenge, now reissuing also their old recordings in hi-res digital formats, and offering them for download via major web stores.

Personally having no doubt about hi-res advantages, or about high end audio future being significantly associated to some kind of it, and proudly just signing myself to the world's first non-oversampling 192 kHz / 24 bits USB D/A converter, step into the real world of hi-res recordings at this moment can bring us apparently different perspective though.

Firstly, since the music moved online, the mass-market didn't show a tendency to download the music even in CD quality, and up to now it looked by significant part rather satisfied with 44.1/16 compressed into lossy mp3. A vast majority of today's music downloads, which is the most increasing part of music market, are almost entirely mp3, or other similar compressed formats downloads. This is certainly to big extent caused by relatively insufficient bandwidth of currently standard internet connections for convenient download of uncompressed files,⁴ but then again, one shouldn't neglect significant participation of consumers which are not that addicted to the actual subjective audio qualities. Anyway, this is how the things settled on, and how they work for now, and this may be the strongest reason why many music publishers are reluctant to invest further into quality, and, as a part of such an investment, to move to a higher sampling rates and bit depths as standard ones.

And there is also another, at this moment maybe less discussed, but ultimately the same important issue, and it is about recording side. The good sound is far from being all about nominal sampling frequency and number of bits, both during recording and playback. At recording side it is about adequate acoustics, adequate microphone setup, good recording amplifiers and mixing and other gear, and their use in the first place. Recordings are and will remain good and bad ones, and no format will change this.

One particular problem with "special" hi-resolution recordings comes into consideration though: many new "hi-res recordings", just as many so-called "audiophile recordings", suffer of superfluous attempts to barely impress, trying to aggressively convince the listeners into advantages of new format.⁵ Such recordings, as "tweaked" as they are, have nothing to do with actual quality that new formats bring to the table. In addition, many of them are still done by applying brickwall antialiasing filters during the A/D process, which mostly negates hi-res advantages. With such a treatment, it is hard to understand, and there is no reason to expect real benefits of hi-res format.

And this is a somewhat paradoxical situation: these and similar issues coming from recording side, just because they are basically coming from people who should be most interested in the audio quality, might be the most important to correct, to bring the hi-res into more significant reality.⁶

Hopefully, the things in this regard will improve soon. In the longer terms, it is important to draw the line: hi-resolution is not here to save suboptimal or bad recordings, or to bring tolerance regarding the bad recording techniques - it is here to overcome the limitations of "low-res" CD format - no more, and no less.

Pages 3 and 4 of this article will particularly discuss these limitations in frequency / time domain, i.e. limitations associated to the sampling frequency.

Increase in resolution in the amplitude domain, i.e. bit depth, should be also taken into account, though the amplitude domain was never that controversial as time / frequency domain topics of CD format. Basically, problem with resolution in the amplitude domain is associated to the "quantization error", and it gets more critical at low levels. Apparently, 16 bits depth appears sufficient for performance at full level, however at lower levels, where number of available bits decreases, the things get much more critical. Thus, a THD of 16 bits format decreases from about 0.001% at full level to about 0.1% at -40 dBFS, and about 1% at -60dBFS. The content of these artifacts might not be sonically benign, as it turns some microdynamics into signal correlated distortion. Different dithering techniques were hence developed to randomize this correlated nature of these artifacts, hence especially improving on low level performance, however a higher bit depth can be normally welcome.

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¹ - We will limit ourselves here to the (linear) PCM audio and put the DSD / SACD approach aside, since it is about to disappear commercially, for some time at least.

² - Please however note that this "media gets inexpensive" statement doesn't equal or suggest anything like "music gets cheap", and I will never support any similar statement or point of view. The music itself, and work of musicians, deserves and requires adequate financial basement, or it is sentenced to disappear otherwise. Hence I sincerely hope that the music production will find its way through all these changes.

³ - One hour of 192/24 material is about 2 GB in size. Savings of up to 50% can be made by using lossless compression methods though.

⁴ - With compression ratio of 11:1, the most often used 128 kbit/s mp3 requires less than 60 MB to compress one typical CD (650 MB).

⁵ - Problems with natural reverberation appear most obvious to me, whether it is emphasized, or missing, to emphasize the instruments. Listeners should supposedly perceive either of these artificial effects as "improvement". I remember practically the same approach was used more than two decades ago, to "convince" listeners how DDD "pedigreed" CDs are better than AAD ones.

⁶ - On the other hand, many standard new recordings are intentionally processed during re-mastering (post-production), in a beneficial way when playback at cheap gear or in noisy environment comes into consideration. Recording industry developed many techniques for this purpose, as of late the most known probably being the one commonly referred to as Loudness War. Supposedly, hi-resolution is intended to aficionados, and re-mastering would avoid to use such techniques.