xiphmont’s ‘There is no point to distributing music in 24 bit/192 kHz’, Article: “24/192 Music Downloads are Very Silly Indeed” Options

[NullC]

This leaves us with degradation of fidelity as a result of processing unnecessary ultrasonics. Unfortunately the very same tests (Meyer and Moran) we used to make our case previously now mitigate against us. If a 16/44k1 bottleneck is inaudible in a system avowedly processing ultrasonics, then the ultrasonics cannot reasonably be said to have (audibly) degraded the sound.

There have been plenty of results that show 'audibility' of ultrasonics that result from failing to prevent the distortion (and a number of the presentation on the subject that have negative results spend a lot of time walking over all the external distortion sources they had to control for). You can probably easily generate such a result for yourself at home (at least the audio output of my laptop produces pretty impressive distortion when a 21khz signal that I can't hear is present).

Perhaps its ultimately not that big a deal— but that space is still space that could be better put to use providing surround, useful multitrack, or redundancy for error correction to make the files resistant to damage even if you do think that the space (and bandwidth) is cheap enough that it's not worth worrying about. Of course, if you're already track separated surround corruption protected files and still think the space is cheap— then by all means, give me 24/192— I can filter out the ultrasonics that would make my amp distort on my end.

[wakibaki]

I thought he made good points, but he quoted Meyer and Moran. I just think it's better that we're all informed as to the counter-arguments rather than ending up with egg on our faces.

I hate the way science-based electronics has been infected by this insanity, but there was a time when audio wasn't like this, and I believe the tide will turn.

w

[pdq]

Not to be nitpicky, but IMHO you only dither if you resample digitally?

You only dither if you go from a higher bit depth to a lower one. I don't recall if in that study the A/D was more than 16 bits.

[BearcatSandor]

The article mentions that SACDs often sound better because they are 'mastered better'. This is something i've been wondering about. Is it worth collecting DVD-As and SACDs because thay may be 'mastered better'? Does that mean they compare favorably with original master recording labels like Mobile Fidelity Sounds Labs, DCC and Audio Fidelity, or are they usually the same old victems of the loudness war just shoved into a bigger 24-bit evelope. I'd think if they were higher quality (re)masters they'd advertise that on the packaging to grab the audiophile market.

This confuses me.

[BearcatSandor]

I'm happy to see a truly coherent argument against the necessity for higher bit depths and sample rates.

Waste of storage space is a small margin of disadvantage however. The advocates of 24/96 and higher were happy to pay the cost of increased storage space to achieve a perceived advantage, and storage space (or transmission bandwidth) is an increasingly cheap commodity.

Have there been 16-bit/44.1k descrete surround sound formats that were sucessfully marketed? Woudn''t that seem like a logical thing?

[WernerO]

Not to be nitpicky, but IMHO you only dither if you resample digitally?

You only dither if you go from a higher bit depth to a lower one.

You dither whenever resolution is reduced. This includes analogue to digital conversion as a limit case.

The analogue input of the ADC ideally contains a noise source at the required level.

In practice the front-end electronics and signal chain often provide this noise implicitly, although not
necessarily with the optimal spectral distribution.

[soulsearchingsun]

Not to be nitpicky, but IMHO you only dither if you resample digitally?

You only dither if you go from a higher bit depth to a lower one.

Oops

You dither whenever resolution is reduced. This includes analogue to digital conversion as a limit case.

The analogue input of the ADC ideally contains a noise source at the required level.

In practice the front-end electronics and signal chain often provide this noise implicitly, although not
necessarily with the optimal spectral distribution.

Thank you, didn't know this. Sounds plausible.

[2Bdecided]

I think this is a fantastic article.


Without wishing to reduce it's value, or claim that the following is audible, there's one small point I'd take issue with. With wide bandwidth recordings, there are more ultrasonics to cause intermodulation distortion, it's true. BUT in most recordings of real instruments, the harmonics are just that - harmonics. Whereas with "badly" reproduced 44.1kHz audio, the high frequencies that escape through the anti-image filter aren't real harmonics at all, they're images of real harmonics.

Like it or not, with most commercial converters (A>D and D>A) the 20-24kHz range (especially the 21-23kHz range) isn't "clean" - there are easily measurable aliases and images - these are trivial to see with extreme source content.

If you filter 44.1kHz audio at about 20kHz, quite gently, ensuring little ringing, and no content above ~21kHz, then you're home and dry. The same would prevent IMD issues with wide bandwidth recordings.

Point is, if you're less careful in either case, the IMD from wide bandwidth recordings has a closer* harmonic relationship with the original music than the IMD from images+aliases+ringing.

Though on any reasonable measure, there's a lot more of it, so any theoretical advantage in terms of "benign"* spectral components is probably outweighed by their amplitude.

* - harmonics can still create some very weirdly related IMD - but aliases and images + IMD create even less well related spectral components.



But I love the article. I love the analogy with light.

Cheers,
David.

[Porcus]

My sixth sense (i.e., my faithful placebo) just took an hour break from its ever enduring task of convincing me how bad -V0 sounds,
just to enlighten Ye all on where the hi-res race will take us from here:

• old recordings made with equipment far short of 192/24 (including recordings digitally recorded and mixed at 48kHz) will be remastered at 192/24;
• people will buy 192/24's and some smartass will compare to the ripped CD, finding that [F|A]LACing both files will keep the hi-res down at, say, 15% above the CD rip size;
• this will be taken as proof that WAVE sounds better than lossless compression -- otherwise it wouldn't be able to keep a 6x as big file down below the size of a CDrip.wav;
• others will point out that good'ole analogue recordings, with all the ultrasonic tape hiss (that probably was never recorded, but is played-back now), cannot be compressed equally well, another proof of the shortcoming of the CD format;
• the ultrasonics will produce intermodulation distortion in hi-fi which were designed at reproducing only the audible range. Equipment A which isn't sufficiently protected against 96 kHz signal, will get the thumbs down from audiophiles worldwide (and some of it will even go up in flames in a comparison against equipment B, so that the subsequently played 'X' can be identified correctly as 'B' with nearly 100% hit rate). Their explanation will be closer to truth than much other snakeoil marketing -- you just have to replace the 'failure to cope with harmful noise' with 'failure to cope with higher fidelity signal'
• loudspeaker manufacturers will produce and fit ultratweeters for the ultrasonic domain, at the praises from audiophiles worldwide. And lo and behold, there will every now and then be a found a thoughtless 'high-quality crossover that relieves the tweeter at 22 kHz' phrase in a marketing web page;
• economists will confirm the modest increase in annual GDP, a sign that everyone is happier (bar some grumpy misers over at hydrogenaudio.org).

Kindly brought to you by Porcus Prophecies, Inc.
(with all reservations for mild exaggregations, a bias which my faithful placebo might sometimes be prone to)

This post has been edited by Porcus: Mar 7 2012, 13:00

[icstm]

This article is a perfect answer to my FIRST question <-- me really happy


In the slashdot article there is a great comment that really starts to provide a robust defence to all those who don't want to beleive the science of it all

I also spent 4 years studying an EE degree, and although it was not especially focused on signal processing, I now work for a large pro audio company.

Some of the issues pointed to in this and other posts regarding oversampling and AA filters are not really relevant to the subject at hand, given the technology currently in use. A statement like 'oversampling at 192 kHz' shows a lack of knowledge regarding the kinds of audio converters that have been in use for a good while now. A Delta Sigma ADC running with an Fs of 48 kHz might often be oversampling at 3.072 MHz or 6.144 MHz. Anti aliasing filters that many people have mentioned are implemented digitally inside the converter (no need for external analog filters, which may well exhibit many of the problems mentioned), and actually have extremely good pass band ripple.

Look at datasheets for converters from manufacturers such as TI (burr brown) [ti.com], cirrus [cirrus.com] [page 36 here has detailed plots of 48, 96, and 192 kHz pass pand characterisitcs for the device, highlighting the fact that increasing the sampling rate does not improve pass band ripple for this device (also note the scale is 0.02 dB/div)], AKM [asahi-kasei.co.jp], Wolfson micro [wolfsonmicro.com] You will find pass band pass responses that are flat to within less than +/- 0.05 dB over the audible range, and stop band attenuation in excess of 100 dB, whether sampling at 48 kHz or 192 kHz. If you can find anything in actual converter datasheets that points to better converter performance from selecting a higher sampling rate, I would be interested to see it.

All in all, the basics of sampling theory don't really help people to understant the real world issues in designing a moden high end audio device. And in the end, surely the proof of the pudding is in the blind tests, that never seem to show that anybody can tell any difference when moving to higher rates? Even if there were a few people who could hear this difference in some perfect listening envirmonment, would it really make sense for everyone else to go out and buy 192 kHz equipment?

[xiphmont]

Oooh, ow. Guess it wasn't that good then, huh?

[xiphmont]

I thought he made good points, but he quoted Meyer and Moran. I just think it's better that we're all informed as to the counter-arguments rather than ending up with egg on our faces.

I'm actually curious as to your specific objection/concern. I've read the various critiques written by detractors of the BAS tests over the years, but too many of those arguments relied on willful obtuseness and eye rolling. I'd like to hear the methodology/implementation critiques from those who nevertheless agreed with the conclusions.

The point has also been made that [in the article] first I argue "ultrasonics hurt fidelity" and then cite M&M, which supposedly undermines the argument because no one could hear a difference. In no way does M&M rebut the assertion that ultrasonics _can_ cause audible distortion. They were using high end setups designed at expense for audiophile-grade frequency extension, and the results show they obviously weren't affected by audible IMD. Am I missing something else?

[Porcus]

The point has also been made that [in the article] first I argue "ultrasonics hurt fidelity" and then cite M&M, which supposedly undermines the argument because no one could hear a difference. In no way does M&M rebut the assertion that ultrasonics _can_ cause audible distortion. They were using high end setups designed at expense for audiophile-grade frequency extension, and the results show they obviously weren't affected by audible IMD. Am I missing something else?

This is kind of 'the negation of never isn't always but sometimes', right?

If some but not all hi-fi's are robust enough not to intermodulate when fed ultrasonics, while other fairly common equipment would be overloaded, degrade sound or even be damaged, then it isn't ill-justified to dub an 88.2 or above format 'harmful'. It is a matter of degree, severity and even of opinion, but just the mere fact that some equipment are off the hook, does not invalidate the labeling.

(Remember, tobacco smoking probably kills only a _{[forty-something percent]} minority of its users.)

[icstm]

If some but not all hi-fi's are robust enough not to intermodulate when fed ultrasonics, while other fairly common equipment would be overloaded, degrade sound or even be damaged, then it isn't ill-justified to dub an 88.2 or above format 'harmful'. It is a matter of degree, severity and even of opinion, but just the mere fact that some equipment are off the hook, does not invalidate the labeling.

(Remember, tobacco smoking probably kills only a _{[forty-something percent]} minority of its users.)

how does it do damage? (ultrasonics, not smoking...)

This post has been edited by icstm: Mar 9 2012, 16:17

[Canar]

Oooh, ow. Guess it wasn't that good then, huh?

I've been waiting for this article for a long time, Monty. My deepest, sincerest thanks.

[greynol]

how does it do damage? (ultrasonics, not smoking...)

I think he means to the sound, not the equipment. Otherwise you did read the presentation, right?

[Porcus]

how does it do damage? (ultrasonics, not smoking...)

I think he means to the sound, not the equipment. Otherwise you did read the presentation, right?

Meant sound (intermodulation distortion), cannot rule out that equipment can be damaged. First, clipping (or square/sharp pulses) are in a Fourier setting, overtones. They had better be filtered. Second, user won't turn down ultrasonics just because it's too loud for a tweeter.

[krabapple]

The article mentions that SACDs often sound better because they are 'mastered better'. This is something i've been wondering about. Is it worth collecting DVD-As and SACDs because thay may be 'mastered better'? Does that mean they compare favorably with original master recording labels like Mobile Fidelity Sounds Labs, DCC and Audio Fidelity, or are they usually the same old victems of the loudness war just shoved into a bigger 24-bit evelope.

They might be. Or might not be. There is no guarantee and no way to know for sure in advance.

I'd think if they were higher quality (re)masters they'd advertise that on the packaging to grab the audiophile market.

For awhile, simply slapping 'SACD' or 'high resolution' on the release was enough to convince gullible audiophiles that a remaster was 'better sounding'.

(For some uneducated consumers, it still is.)

In its favor, the SACD 'Scarlet Book' format specification (unlike the CD 'Redbook' spec) discouraged loudness-war-type mastering for the DSD layer of SACDs. But recording engineers know how to get around such minor obstacles. At the most basic level, they can just smash the life out of the record before it's even converted for a 'hi rez' release. That's what happened to Oasis 'What's the Story Morning Glory' -- the SACD was no more dynamic than the CD, because the master tape itself has already been leeched of dynamic range. No degree of 'high resolution' remastering is going to increase the dynamic range of that recording. (Of course, the folks who mastered that album in the mid 1990s had no inkling there'd be an SACD version in its future.)

There are some verified cases where the DSD layer is a more 'dynamic' mastering than the Redbook layer of the same SACD disc -- Pink Floyd's 'Dark Side of the Moon' SACD is the famous example. This was a mastering choice, not a technical necessity.

This post has been edited by krabapple: Mar 9 2012, 23:20

[krabapple]

I thought he made good points, but he quoted Meyer and Moran. I just think it's better that we're all informed as to the counter-arguments rather than ending up with egg on our faces.

I'm actually curious as to your specific objection/concern. I've read the various critiques written by detractors of the BAS tests over the years, but too many of those arguments relied on willful obtuseness and eye rolling. I'd like to hear the methodology/implementation critiques from those who nevertheless agreed with the conclusions.

The point has also been made that [in the article] first I argue "ultrasonics hurt fidelity" and then cite M&M, which supposedly undermines the argument because no one could hear a difference. In no way does M&M rebut the assertion that ultrasonics _can_ cause audible distortion. They were using high end setups designed at expense for audiophile-grade frequency extension, and the results show they obviously weren't affected by audible IMD. Am I missing something else?

The supposed stake through the heart of M&M is that they didn't use 'any' (later changed to 'they didn't use ENOUGH') pure DSD (i.e., not sourced from analog tape or 'standard rez' digital) recordings as test material. This ignores the fact that subjects were often allowed to pick the discs THEY thought best showed the difference. It also conveniently 'forgets' that SACDs were touted as inherently improving *even analog-sourced materials* -- and indeed, most non-classical SACDs were and are sourced from analog tapes. They're only rarely new recordings. (Some Sony SACDs were reportedly even sourced from Redbook masters. )

So 'skeptical' complaints against M&M on these fronts really just constituted moving the goalposts. Suddenly only 'pure' DSD recordings reveal the benefits of the format! (Leaving aside that the relatively large ultrasonic content of such recordings could cause distortion. Though SACD players usually have 50- or 100kHz lowpass filters after the DAC, to cut out the REALLY ultra junk.)

That said, M&M absolutely *should* have described their methods in far more detail in the original article (that information dribbled out later). And they *could* publish subset analysis of data to see if considering only the 'pure' DSD recordings made any difference in their findings. Or release their raw data and let others work it over. Or, preferably, someone could do another test and gather more data.

[LaserSokrates]

An excellent read, thank you very much! A bit deeper (as in practical) than the stuff I heard at the university, but perfectly understandable nevertheless.

[xiphmont]

That said, M&M absolutely *should* have described their methods in far more detail in the original article (that information dribbled out later). And they *could* publish subset analysis of data to see if considering only the 'pure' DSD recordings made any difference in their findings. Or release their raw data and let others work it over. Or, preferably, someone could do another test and gather more data.

Excellent, thanks. I'll ask about it at this month's meeting.

[krabapple]

Excellent, thanks. I'll ask about it at this month's meeting.

No problem. Loved your article, btw.

Dave Moran addressed some of the 'skeptics' head-on in a contentious exchange on the sa-cd.net forum. Here's one possible entry point into that:

http://www.sa-cd.net/showthread.php?page=1

And from this newer thread on that forum -- about your article -- one can see right off that the True Believers already consider M&M's study to have been 'debunked':

http://www.sa-cd.net/showthread.php?page=1

This post has been edited by krabapple: Mar 10 2012, 23:15

[hellokeith]

Does the statement of the benefits of mixing/mastering >44/16 also extend to recording? Or record at 44/16 and then upconvert for mixing/mastering?

[Wombat]

At first i have to congrat Monty that he gave us this article.
For some this article might be the answer as the concept of the enemy responding to the famous braindead TAS articles spreaded lately.
Unfortunately it seems that in the places that were hearing different before this only made people trip for one moment and then they returned to old thinking.
There only has to come in one person to the discussion with some weird numbers no one challenges and this article is declared wrong.
On the other hand I did read over forums like computeraudiophile lately, since JimH pointed there and enjoyed the latest writings.
Greetings to Julf this way for his hard work btw.

So again i have to thank for this article that finaly set of an avalanche of discussion on several places on the web in the right direction

[FreaqyFrequency]

post

For the sake of the sanity and for spared minutes of the lives of everyone reading this thread, and for the love of humanity, do not read the thread corresponding to Monty's article on the SACD threads linked. Please.

Please.