Skip to main content

Topic: ESS claim DAC pushes the boundaries of audio science (Read 11995 times) previous topic - next topic

0 Members and 1 Guest are viewing this topic.
  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #25
About 10 minutes into the presentation it misidentifies dither as noise shaping.
No, he says the signal is dithering around, and puts the word dither in quotes. I think he knows full well it's not conventional dither he's talking about.


I can well believe the graphs he's showing. I would question audibility. I would question how the DAC responds to real-world signals. It's not just that it's hard to measure and show the (real) performance issues he's describing once you use real signals - it's that the noise in real signals randomises those problems so well that both measurement equipment and ears struggle to pick it up any more. There are/were SDM problems that did crop up in an apparently unpredictable ways with some real signals, but most companies believe those problems are solved.

It's a fascinating talk. There are some great, insightful examples in there (not least the very last one). However, he accepts the audibility of high (ultrasonic) frequencies as read, so...

I looked at the YouTube channel it's in - there are many other fascinating talks in the same channel (many from familiar names) which I wish I had time to listen to - but you will note very quickly that many of the people talking do not take the same approach to audio as HA - so while you may learn something, expect to find things that you totally disagree with...

http://www.youtube.com/user/RMAudiofest?feature=watch

Cheers,
David.

  • Willakan
  • [*][*]
ESS claim DAC pushes the boundaries of audio science
Reply #26
There's certainly no shortage of contentious claims in that channel, from ESS and others...from ESS we've got the aforementioned jitter, super-secret-DAC-flaw and ultrasonic revelations, whilst other videos take as a given that high-res audio is not only necessary, but obviously can't quite match the resolution of analog tape.

Just to polish it all off, we have an "explanation" of why all the cables actually do sound different. From a panel consisting entirely of ultra "high-end" cable manufacturers.

  • Hotsoup
  • [*][*][*]
ESS claim DAC pushes the boundaries of audio science
Reply #27
...take as a given that high-res audio is not only necessary, but obviously can't quite match the resolution of analog tape.

Ah yes, the old "Analog-Sounding Digital: Are We There Yet?" POV. A few more bits and samples per second and we'll be there!!! /sarcasm

  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #28
This one is quite interesting...
http://www.youtube.com/watch?v=pEWgNLHVJjU
...how ultra-hi-end audio wants to be like Gucci and Mercedes, but is failing.

I haven't listened to the loudness wars one yet...
http://www.youtube.com/watch?v=7a50DcK2its
EDIT: He had me at "I'd rather listen to a 192kbps AAC with full dynamic range, than a 24/192kHz lossless file with heavy dynamic range compression".
But then he lost me again saying how great glass CDs sound.

Cheers,
David.
  • Last Edit: 25 January, 2013, 05:46:44 AM by 2Bdecided

  • Woodinville
  • [*][*][*][*][*]
ESS claim DAC pushes the boundaries of audio science
Reply #29
Digital will not sound like analog until we start adding distortion into digital appropriately.

Shall we?
-----
J. D. (jj) Johnston

  • dhromed
  • [*][*][*][*][*]
ESS claim DAC pushes the boundaries of audio science
Reply #30
so while you may learn something, expect to find things that you totally disagree with...


I'm not sure I want to sift through the mud to get to the gold, especially when in my armchair position it's difficult to distinguish the two if they're both shiny.

ESS claim DAC pushes the boundaries of audio science
Reply #31
About 10 minutes into the presentation it misidentifies dither as noise shaping.
No, he says the signal is dithering around, and puts the word dither in quotes. I think he knows full well it's not conventional dither he's talking about.


Please provide the time in the video where that takes place.

Maybe we're not watching the same video, because the one I'm watching starts mentioning noise shaping at 8:02, but the slide' graphic shows dither. The slide specifically mentions noise shaping, and AFAIK dither has not been mentioned at all at this point. Actually, the voice comments at that point seems to be describing the operation of a successive-approximation converter. But the slide says quite clearly "Noise shaping".

  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #32
Maybe we're not watching the same video, because the one I'm watching starts mentioning noise shaping at 8:02, but the slide' graphic shows dither. The slide specifically mentions noise shaping, and AFAIK dither has not been mentioned at all at this point. Actually, the voice comments at that point seems to be describing the operation of a successive-approximation converter. But the slide says quite clearly "Noise shaping".
If you use low order noise shaping without dither, it'll look a bit like those graphs. The graphs are clearly drawn in a graphics package, not real (he's got the step size wrong on the green "noise shaped" graph for one thing), but he is showing noise shaping.

Of course, he could equally well be showing lousy dither. If you think you can tell the difference between an artistic representation of non-optimal dither, and an artistic representation of low order noise shaping, then can I respectfully suggest that you don't know what at least one of them really looks like.

Cheers,
David.

  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #33
I'm not sure I want to sift through the mud to get to the gold
Are you going to miss out on the chance to listen to Matt Ashland (Monkey's Audio, J River) talking about the various windows audio output modes (which ones are always bit perfect, sometimes bit perfect, never bit perfect, etc), and then telling a room full of self-professed industry-leading audiophiles that they won't be able to hear the difference?

Quote
especially when in my armchair position it's difficult to distinguish the two if they're both shiny.
I guess if you don't have a highly tuned BS meter it may be better to stay away.

Cheers,
David.

ESS claim DAC pushes the boundaries of audio science
Reply #34
Maybe we're not watching the same video, because the one I'm watching starts mentioning noise shaping at 8:02, but the slide' graphic shows dither. The slide specifically mentions noise shaping, and AFAIK dither has not been mentioned at all at this point. Actually, the voice comments at that point seems to be describing the operation of a successive-approximation converter. But the slide says quite clearly "Noise shaping".
If you use low order noise shaping without dither, it'll look a bit like those graphs. The graphs are clearly drawn in a graphics package, not real (he's got the step size wrong on the green "noise shaped" graph for one thing), but he is showing noise shaping.


Can't be.

Just to remind you, here's a really pretty good definition of noise shaping from Wikipedia:

"
Noise shaping is a technique typically used in digital audio, image, and video processing, usually in combination with dithering, as part of the process of quantization or bit-depth reduction of a digital signal. Its purpose is to increase the apparent signal to noise ratio of the resultant signal. It does this by altering the spectral shape of the error that is introduced by dithering and quantization; such that the noise power is at a lower level in frequency bands at which noise is perceived to be more undesirable and at a correspondingly higher level in bands where it is perceived to be less undesirable. A popular noise shaping algorithm used in image processing is known as ‘Floyd Steinberg dithering’; and many noise shaping algorithms used in audio processing are based on an ‘Absolute threshold of hearing’ mode
"

The key part of this definition is "Its (noise shaping) purpose is to increase the apparent signal to noise ratio of the resultant signal. It does this by altering the spectral shape of the error that is introduced by dithering and quantization; such that the noise power is at a lower level in frequency bands at which noise is perceived to be more undesirable and at a correspondingly higher level in bands where it is perceived to be less undesirable."

The long and the short of it is that noise shaping takes place in the frequency domain. Until one shows something going on in the time or frequency domain, they aren't sensibly talking about noise shaping.

Since the diagram he shows is clearly in the amplitude domain, he is not sensibly talking about noise shaping. My most charitable judgement is that he was  talking about dithering even though his discussion of pump gas prices sounded more like a discussion of successive approximation.

Bottom line, I think this guy was giving a mish-mash of every lecture and book he ever read or heard about DACs, about all 3 of them (!!!), jammed aimlessly into something that made sense to him, but can't actually make sense to anybody who has a proper understanding of what he was conflating and muddling through.
  • Last Edit: 25 January, 2013, 10:38:55 AM by Arnold B. Krueger

  • benski
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #35
The long and the short of it is that noise shaping takes place in the frequency domain. Until one shows something going on in the time or frequency domain, they aren't sensibly talking about noise shaping.


What are you talking about?

You read the wikipedia article but you clearly did not look at the math.  Error-shaping clearly happens in the time domain.  The gas station example is a near-perfect example of first-order error-shaping.  Noise-shaping happens by adding dither and a filter.  The fact that we can color via the filter does not make any of the math or practical operations happens in the frequency domain.
  • Last Edit: 25 January, 2013, 11:28:45 AM by benski

  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #36
What are you talking about?

You read the wikipedia article...
ouch!  FWIW, while I wouldn't even claim to be up to speed on noise shaping these days, never mind a world expert, I have at least designed them in the recent-ish past.
Quote
...but you clearly did not look at the math.  Error-shaping clearly happens in the time domain.  The gas station example is a near-perfect example of first-order error-shaping.  Noise-shaping happens by adding dither and a filter.
You don't need dither for noise shaping. You just "shape" the quantisation noise.

This is good, but sadly some of the images are rather fuzzy...
http://www.essex.ac.uk/csee/research/audio...aping%20IOA.pdf

The HA knowledge base is fine too, though note in this picture...
http://wiki.hydrogenaudio.org/index.php?ti...oiseshaper3.png
...you don't need the dither, and strictly speaking you don't need H(z) (i.e. the filter) either, as the noise still gets shaped just by delaying it by one sample and subtracting it from the input. That just gives a very simple rising-with-frequency characteristic.

Cheers,
David.
  • Last Edit: 25 January, 2013, 11:55:56 AM by 2Bdecided

  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #37
I guess if you don't have a highly tuned BS meter it may be better to stay away.
...though if you want to explode with incredulity, try this one...
http://www.youtube.com/watch?v=NJ3HRjFI6F0

"44.1kHz can't capture the phase of a 20kHz signal"
"We can detect an interaural delay of 2.5us which implies 350kHz"
"There's no point converting between DSD and 24/96 because it ruins the original so much, and neither is as good as analogue"

...and yet, some of those people make very nice sounding recordings. As one of the panel members says "I don't think the format matters - these people are particular about their choice of format in the same way that they're particular about everything else - and it's that care with other more important things that creates great results".

Cheers,
David.
  • Last Edit: 25 January, 2013, 12:00:45 PM by 2Bdecided

ESS claim DAC pushes the boundaries of audio science
Reply #38
The long and the short of it is that noise shaping takes place in the frequency domain. Until one shows something going on in the time or frequency domain, they aren't sensibly talking about noise shaping.


What are you talking about?


Something that is really pretty clear - spectral shaping of quantization noise in order to obtain a perceived dynamic range advantage. IOW, nois shaping is forcing the energy in the quanlization error to the high frequency end of the audio band in such a way that is far less audible.

Those of us who have implemented our own noise shaping schemes are probably more aware of this than people with only a mathematical involvement.

Quote
You read the Wikipedia article but you clearly did not look at the math.


Interesting how well you read minds.    Interestingly enough while the Wikipedia article on noise shaping defines it properly, its content under "How noise shaping works" seems to be about delta-sigma converters, and ignores a ton of prior art.  There was noise shaping long before there were any feedback loops to use to implement it.  Your statement "Noise-shaping happens by adding dither and a filter" reflects the prior art that I am now speaking of. 

I will speculate (since I can't possibly actually know for sure) that if you read and understood the Wikipedia article you'd see that the math did not exactly match your own comment.

Quote
Error-shaping clearly happens in the time domain.


Yes, and...

Quote
The gas station example is a near-perfect example of first-order error-shaping.


In what alternative universe?  It's about accumulating error until it sums up to being a whole unit which has an intermittent outcome. First order error shaping is about consistently and steadily feeding back with a time delay.

BTW, the presentation at this point has specifically said that it was not about modern DACs which of course are Delta-Sigma.

Quote
Noise-shaping happens by adding dither and a filter.


True in some cases but not necessarily true. The dither + filter methodology relates to earlier technology than Delta-Sigma.

Noise shaping might be a bit of a misnomer. The noise in question is quantization error, which is not random noise but is a 100% predictable signal. Very old school terminology but nobody changes it.

Quote
The fact that we can color via the filter does not make any of the math or practical operations happens in the frequency domain.


In what alternative universe?  The whole purpose of coloring or spectral shaping via the filter is to make changes to the spectral content of the quantization error that reduce the perception of the error signal.

I can't believe that regulars on this forum don't understand that noise shaping relates to the frequency spectrum content of the quantization error and has more than one implementation depending on the design of the rest of the converter or quantizer.  However, it appears that Wikipedia may have made a similar  mistake in a way.

  • benski
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #39
and strictly speaking you don't need H(z) (i.e. the filter) either, as the noise still gets shaped just by delaying it by one sample and subtracting it from the input. That just gives a very simple rising-with-frequency characteristic.

Ahh, but it's still technically a filter

ESS claim DAC pushes the boundaries of audio science
Reply #40
and strictly speaking you don't need H(z) (i.e. the filter) either, as the noise still gets shaped just by delaying it by one sample and subtracting it from the input. That just gives a very simple rising-with-frequency characteristic.

Ahh, but it's still technically a filter


Exactly!

It appears that our correspondent can't see the desired outcome for all of the implementation details. ;-)

Maybe his blood sugar is low and he needs to take his lunch!

  • db1989
  • [*][*][*][*][*]
  • Global Moderator
ESS claim DAC pushes the boundaries of audio science
Reply #41
If he hasn’t had his lunch yet, his blood glucose may well be low, considering that it’s dinner-time in the UK!

ESS claim DAC pushes the boundaries of audio science
Reply #42
I guess if you don't have a highly tuned BS meter it may be better to stay away.
...though if you want to explode with incredulity, try this one...
http://www.youtube.com/watch?v=NJ3HRjFI6F0

"44.1kHz can't capture the phase of a 20kHz signal"
"We can detect an interaural delay of 2.5us which implies 350kHz"
"There's no point converting between DSD and 24/96 because it ruins the original so much, and neither is as good as analogue"

...and yet, some of those people make very nice sounding recordings. As one of the panel members says "I don't think the format matters - these people are particular about their choice of format in the same way that they're particular about everything else - and it's that care with other more important things that creates great results".



Especially given the obvious superannuation of the panel members, in ArnyWorld the panel discussion would have 2 steps:

(1) Each panel member brings his favorite SACDs and DVD-As and has to pass a DBT of the Meyer-Moran persuasion

(2)  The actual panel discussion involves only those who survive step (1).

Something about the sound of one hand clapping, or would that be no hands clapping? ;-)

  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #43
and strictly speaking you don't need H(z) (i.e. the filter) either, as the noise still gets shaped just by delaying it by one sample and subtracting it from the input. That just gives a very simple rising-with-frequency characteristic.

Ahh, but it's still technically a filter
I know delay one sample and subtract is a filter. H(z) is "the filter" in the article that pictures comes from...
http://wiki.hydrogenaudio.org/index.php?title=Noise_shaping
The point is you are still "noise shaping" without putting an explicit filter (e.g. some psychoacoustically optimised thing) in the feedback loop.

And it is just such a simple topology that really could give rise to graphs rather like those in the presentation. Due to noise shaping. Without dither.

Cheers,
David.
  • Last Edit: 25 January, 2013, 01:50:32 PM by 2Bdecided

  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #44
(1) Each panel member brings his favorite SACDs and DVD-As and has to pass a DBT of the Meyer-Moran persuasion
I think we'd all like to see that.

I wouldn't ban them from the panel for failing though - I'd just ask them to talk about the things that really make their recordings sound great. It would be interesting to blind test many of those too. My person feeling is great venue, great performers, "magic" microphone placement, good equipment, not too much messing around with the sound = great result. IMO that has been true (and achievable, at reducing cost) for at least five decades.

Cheers,
David.

  • 2Bdecided
  • [*][*][*][*][*]
  • Developer
ESS claim DAC pushes the boundaries of audio science
Reply #45
If he hasn’t had his lunch yet, his blood glucose may well be low, considering that it’s dinner-time in the UK!
Tea time in Yorkshire, tha knows?

  • dhromed
  • [*][*][*][*][*]
ESS claim DAC pushes the boundaries of audio science
Reply #46
Quote
especially when in my armchair position it's difficult to distinguish the two if they're both shiny.
I guess if you don't have a highly tuned BS meter it may be better to stay away.

I mean to say that audio and/or signal processing is neither my job nor my education, that most of what I know comes from this place (and subsequent experiments and documents), so if someone starts yapping about noise shaping in a high-BS environment, I'm at a pretty serious disadvantage. 

I'd rather stay here and read and follow links. Gold nuggets abound!