The No.1 Website for Pro Audio
 Search This Thread  Search This Forum  Search Reviews  Search Gear Database  Search Gear for sale  Search Gearslutz Go Advanced
if higher sample rate doesnt matter then why .... Effects Pedals, Units & Accessories
Old 18th September 2011
  #331
Lives for gear
 
doug hazelrigg's Avatar
Quote:
Originally Posted by narcoman View Post


Okay - I've absolutely explained this enough and we're going round in circles. Take it easy.....
Yes, you did, and magisterially
Old 18th September 2011
  #332
Lives for gear
 
doug hazelrigg's Avatar
I hate it when I quote a post and reply to it, only to find it was answered better by others already
Old 18th September 2011
  #333
Lives for gear
 

Quote:
Originally Posted by psycho_monkey View Post
Well of course there is. You agree a standard! Same way we all drive on one side of the road in a given country...I can take my session from one studio to another, and provided the converters are lined up the same, my gain staging will be the same.

You really are trolling now aren't you? It can't possibly be that you don't grasp this basic concept.
there are LOTS of standards
and many companies/people ignore them
so there is no way to know tht if you give -xxxdBFS to someone else that when they play it it will result in yyydBV or zzzdBSPL or any meaningful number
Old 18th September 2011
  #334
Lives for gear
 

Quote:
Originally Posted by narcoman View Post


Well - for one thing , you can't just design output voltages against reference willy nilly. There are standards to adhere to.....

PROPORTIONALLY, the reference voltage at any given value will be over the nominal value. Read on and see why.....

That isn't what's being discussed!! The only thing that is being discussed is a sample doesn't represent peak code. THAT is all intersample peak means!!

The inter sample peak refers to any reconstruction value over the integral curve being higher than a sample value.

That is all it means. If you can't understand that then I've no idea what to say! It's unbelievable that you'd argue this. What else can anyone say? heh!!


What happens if you SRC a 44.1 set into a 96 set? What happens then?
You got it - some of the reconstructed and NEW samples will be above pairwise 44.1 samples. In other words there will be inter sample peaks with respect to the original 44.1 sample set. Now - the re-coinstruced analogue waveforms will be the same - but that isn't the point.



And nobody has said there are. What they have said is that the peaks in the analogue reconstructed waveform don't necessarily line up with the highest samples in sample code. How could they? We don't join dots!

HOWEVER - the respective sample points do not occur (most of the time) when the voltage is at a locally maximum point.



Once you set a reference - for example

-18dB(FS) = 0dB(VU)

in a 24bit sample set then the number 000111111111111111111111 (actually it won't be exactly that as 6dB is not 1 bit - but it's close enough for getting the point across) is equatable to 0dB(VU). That is core to the idea of calibration.


That is why those of us who do this for a living set standards either locally (on your own) or you obey international convention;

There are several. ITU, AES, EBV, BBC and quite a few more. We set standards and STICK to them year in year out.

Even within hardware there are accepted standards of what 0dB(VU) equates to in terms of voltage! For MOST hardware 0dB(VU) is +4 dBU (not all ).

+4dBU is nominally accepted internationally and across equipment asset at 1.23Vrms.

Now - there are a couple of points to your argument all based around corrupting the central point. It is important when discussing AD and DA that an equivalence is set. However, for ANY digital argument ALL of the points about reference level no matter what value is set as 0dBVU equivalent.

The AES define -18 (or -20 for some use). EBU define -20. The BBC have defined -17, -18 and -20 at various times......

Nobody is confusing analogue and digital because most of us in this discussion are savvy and well versed enough to understand that we all refer to analogue/digital comparisons with a defined reference. The point is - the arguments stand no matter what the reference is; the only thing that changes is the absolute value behind the argument, not the semantics themselves.


Okay - I've absolutely explained this enough and we're going round in circles. Take it easy.....
there are lots of standards
and you should not use them if they cause a problem

you have to confuse digital with analog to make that peak statment

there are no samples in analog domain
the only way to peak in analog is if the reconstructed signal
was bigger than the original sampled signal
if you create a signal in the digital domain
then peaks in the analog domain are meaningless

what you do with uprezzing in the digital domain has nothing to do with the analog domain
the new values will often be higher but so what !!!!!!
meaningless in both domains except for the distortion added
Old 18th September 2011
  #335
Lives for gear
 

Quote:
Originally Posted by dcollins View Post
The existence of inter-sample peaking is not even remotely controversial, so I have no idea what OAG is on about. It's also trivial to demonstrate in D/A (or async. SRC for that matter).

Also, there are many D/A converter chips that have no internal headroom, so the claim that it's just a matter of proper design is also questionable. One would have to digitally attenuate the input to the chip by some number of dB to allow for peaking at the conversion stage................
DC
it should be because it is flat out wrong

any chip without headroom was badly designed
been saying that all along

yes!! if you are worried that the digital will cause the d/a to have problems then you should attenuate it.
you lose nothing as you still get all the analog you ever had but minus the clipping distortion
Old 18th September 2011
  #336
Lives for gear
 

Quote:
Originally Posted by doug hazelrigg View Post
Yes, you did, and magisterially
yes
but
too bad he didnt do it right
Old 18th September 2011
  #337
Gear Head
 

Quote:
Originally Posted by dcollins View Post
Also, there are many D/A converter chips that have no internal headroom, so the claim that it's just a matter of proper design is also questionable. One would have to digitally attenuate the input to the chip by some number of dB to allow for peaking at the conversion stage................
Exactly, agreed!

It has nothing to do with the converters being "badly designed".

This is getting tiresome. The stubborness of OAG's circular arguement has crossed the border in to childish territory.
Old 18th September 2011
  #338
Quote:
Originally Posted by oldeanalogueguy View Post
there are LOTS of standards
and many companies/people ignore them
so there is no way to know tht if you give -xxxdBFS to someone else that when they play it it will result in yyydBV or zzzdBSPL or any meaningful number
That is so totally and utterly not the point! The point is that calibration can provide repeatable and predictable results.

In other words, I'm giving you the instructions on how to put together your ikea wardrobe. Whether you follow those instructions and end up with a wardrobe, or whether you are unable to follow them and end up with a piece of modern art is not necessarily a flaw in the instructions.

There are many standards - but why does that matter? There are many tape lineups as well, but the technical language is there to describe exactly what we mean at the same time. This is clear to anyone who is justified in calling themselves an engineer.
Old 18th September 2011
  #339
Lives for gear
 
DaveUK's Avatar
Incredible .I haven't witnessed this kind of thing before , I've lead quite a sheltered BB life!
When does hitler get mentioned?

Sent from my telemophone using Gearslutz.com App
Old 18th September 2011
  #340
Lives for gear
 
doug hazelrigg's Avatar
Although I disagree with (almost) everything OAG says, it's important I think to let him have his say, not for entertainment value, but because icons and shibboleths need to be questioned from time to time -- keeps us all honest, makes us think about what we claim to know or believe

I mean, it wasn't all THAT long ago I subscribed to popular falsehoods like "bit-hogging" and "even multiple SRC" or the silly assertion that

HIGH SAMPLE RATES SOUND BETTER BECAUSE IT SOUNDS MORE LIKE ANALOGUE
Old 18th September 2011
  #341
Quote:
Originally Posted by doug hazelrigg View Post
Although I disagree with (almost) everything OAG says, it's important I think to let him have his say, not for entertainment value, but because icons and shibboleths need to be questioned from time to time -- keeps us all honest, makes us think about what we claim to know or believe
Would be nice if the questions made sense from time to time though!
Old 18th September 2011
  #342
Moderator
 
narcoman's Avatar
 

Quote:
Originally Posted by oldeanalogueguy View Post
there are lots of standards
and you should not use them if they cause a problem
!!!!! that's a pretty odd one!
Quote:
Originally Posted by oldeanalogueguy View Post
you have to confuse digital with analog to make that peak statement
!!!!
Quote:
Originally Posted by oldeanalogueguy View Post
there are no samples in analog domain
the only way to peak in analog is if the reconstructed signal
was bigger than the original sampled signal
Don't know how many times one has to tell you that the reconstructed signal does not peak at the samples!

Quote:
Originally Posted by oldeanalogueguy View Post
if you create a signal in the digital domain
then peaks in the analog domain are meaningless
eh? That doesn't even BEGIN to make any sense!

Quote:
Originally Posted by oldeanalogueguy View Post
what you do with uprezzing in the digital domain has nothing to do with the analog domain
the new values will often be higher but so what !!!!!!
Correct . It's called an inter sample peak. Higher... higher than? higher than the neighbouring samples. Sort of a "peak" if you will, between the samples. Sort of "inter" yes?heh

And as an "inter sample peak" it addresses some of the issues that happen when we re-construct signals.

I'll find you a nice picture then I'll give up


Here we go.... I know it's not ideal but it'll suffice to illustrate what we're all talking about. I'm convinced that you're thinking of something else....

Look at the nice picture of a very small window of a waveform. Now look at the four sampled points (let's ignore quantisation for now but assume it's nicely dealt with). I draw your attention to the two middle points. Look at the peak between the points. It's a specific voltage not sampled by the time domain samples BUT it doesn't matter. The waveform is correctly sampled EVEN though there is a peak in the waveform between the sample points. This peak is completely and 100% re calculable within the digital domain if we so wish. It's also correctly reconstructed when we go DA. It's a peak that happened between the sample points, it's a peak that is mathematically maintained such that a proportionally correct waveform results from the sample points.

Old 18th September 2011
  #343
Lives for gear
 
duckoff's Avatar
 

What kind of sorcery is this!!
Old 19th September 2011
  #344
Quote:
Originally Posted by duckoff View Post
What kind of sorcery is this!!
heh
Old 19th September 2011
  #345
Lives for gear
 
Old Goat's Avatar
 

Quote:
Originally Posted by doug hazelrigg View Post
Although I disagree with (almost) everything OAG says, it's important I think to let him have his say, not for entertainment value, but because icons and shibboleths need to be questioned from time to time -- keeps us all honest, makes us think about what we claim to know or believe

I mean, it wasn't all THAT long ago I subscribed to popular falsehoods like "bit-hogging" and "even multiple SRC" or the silly assertion that

HIGH SAMPLE RATES SOUND BETTER BECAUSE IT SOUNDS MORE LIKE ANALOGUE
Run, Doug, run like the wind! It's too late for us--save yourself, man!
Old 19th September 2011
  #346
The always generous and patient narcoman seems locked into trying to make the pictures ever bigger and simpler -- and there are no doubt others who are actually learning from his efforts -- certainly I've been happy for the check-up/brush-up, myself; as doug suggests, it's nice to get a good check on your bearings every now and then.

But there's a point where the dialog just goes around and around. And, it's occurred to me that fatigue or other factors could be at play in some of the unproductive nature of the discourse.
Old 19th September 2011
  #347
Gear Head
 

Quote:
Originally Posted by doug hazelrigg View Post
Although I disagree with (almost) everything OAG says, it's important I think to let him have his say, not for entertainment value, but because icons and shibboleths need to be questioned from time to time -- keeps us all honest, makes us think about what we claim to know or believe
I agree, and I think we should all be constantly questioning and exploring things so as to not fall in to arrogant complacency. However, it's easy to go too far with the pedantic semantics and intellectual masturbation, and lose sight of everything else. I would never want to stop anyone having their say. This is, after all, a discussion forum.

I feel for the OP because I'm unsure as to whether he actually believes the explicit arguements he presents, or whether he is attempting to garner a greater understanding of the issue by way of debate. Which if it was the latter, I believe would be helped by modifying the technique of discourse so as not to dominate it with repetitive loops of rhetorical fallacies.

I don't know. Who's really knows anything anyway?
Old 19th September 2011
  #348
Lives for gear
 

Quote:
Originally Posted by narcoman View Post
!!!!! that's a pretty odd one!

!!!!

Don't know how many times one has to tell you that the reconstructed signal does not peak at the samples!


eh? That doesn't even BEGIN to make any sense!


Correct . It's called an inter sample peak. Higher... higher than? higher than the neighbouring samples. Sort of a "peak" if you will, between the samples. Sort of "inter" yes?heh

And as an "inter sample peak" it addresses some of the issues that happen when we re-construct signals.

I'll find you a nice picture then I'll give up


Here we go.... I know it's not ideal but it'll suffice to illustrate what we're all talking about. I'm convinced that you're thinking of something else....

Look at the nice picture of a very small window of a waveform. Now look at the four sampled points (let's ignore quantisation for now but assume it's nicely dealt with). I draw your attention to the two middle points. Look at the peak between the points. It's a specific voltage not sampled by the time domain samples BUT it doesn't matter. The waveform is correctly sampled EVEN though there is a peak in the waveform between the sample points. This peak is completely and 100% re calculable within the digital domain if we so wish. It's also correctly reconstructed when we go DA. It's a peak that happened between the sample points, it's a peak that is mathematically maintained such that a proportionally correct waveform results from the sample points.

Let me state outright that I have absolutely zero knowledge of this subject (which is why I'm reading this thread, to learn something).

But you don't have to be very smart to look at the drawing and wonder: Could not the "inter sample peak" just as easily be an "inter sample dip"?

After all, it occurred between samples, i.e. it was not sampled.

While it would admittedly be highly unlikely that a dip of any significance could occur in such a small "slice" of time, there must be some interpolation going on...
Old 19th September 2011
  #349
Gear Nut
 

I am almost ashamed to admit that I have read every post in this thread.

It seems that the primary disconnect is that OAG insists on using a different definition of the word "peak" (among others) than every other person on the planet. To OAG it appears to only be associated with clipping and not just the highest value reached during a cycle. There have been several excellent posts to clarify the definition and attempt to get OAG on the same page as everyone else. They have all failed. Not because they weren't very clear but because for some reason OAG won't acknowledge the accepted definition of the terms he bandies about.

I feel sorry for the students OAG must have confused in his past and feel fortunate that I didn't have professors of his ilk during my engineering program at Case Western. They were content to use definitions that were consistent with the rest of the engineering community.

Although I know this thread is a complete waste of time I can't seem to ignore it. It's like driving by a car accident. You don't really want to see the carnage but you have to look. On with the carnage...

Don
Old 19th September 2011
  #350
Lives for gear
 
Old Goat's Avatar
 

This is a SWAG, but I'm thinking an intersample trough wouldn't be a problem as far as headroom goes.
Old 19th September 2011
  #351
Lives for gear
 

My 2 cents. Given that intersample peaks are a very real phenomenon it makes perfect sense to design a D/A with a certain amount of analog headroom. A D/A with absolutely no analog headroom is indeed a poor design imo.
Old 19th September 2011
  #352
Quote:
Originally Posted by bdenton View Post
Let me state outright that I have absolutely zero knowledge of this subject (which is why I'm reading this thread, to learn something).

But you don't have to be very smart to look at the drawing and wonder: Could not the "inter sample peak" just as easily be an "inter sample dip"?

After all, it occurred between samples, i.e. it was not sampled.

While it would admittedly be highly unlikely that a dip of any significance could occur in such a small "slice" of time, there must be some interpolation going on...
Such a 'dip' would represent a frequency above the bandlimit.
Old 19th September 2011
  #353
Lives for gear
 
doug hazelrigg's Avatar
Maybe I shouldn't psycho-analyze OAG, but it appears he's backed himself into a corner of an untenable position and at this point has no choice but to fight, perhaps "to the death." Funny, I've been there myself. I don't think he's a troll, but I DO think we should stop feeding him

I'm just glad somebody has asserted that 4 samples are required to reconstruct a wave, instead of just 2, as is popularly asserted. ask anybody who has designed a plug-in that employs oversampling about this!
Old 19th September 2011
  #354
Lives for gear
 

Quote:
Originally Posted by don4777 View Post
I am almost ashamed to admit that I have read every post in this thread.

It seems that the primary disconnect is that OAG insists on using a different definition of the word "peak" (among others) than every other person on the planet. To OAG it appears to only be associated with clipping and not just the highest value reached during a cycle. There have been several excellent posts to clarify the definition and attempt to get OAG on the same page as everyone else. They have all failed. Not because they weren't very clear but because for some reason OAG won't acknowledge the accepted definition of the terms he bandies about.

I feel sorry for the students OAG must have confused in his past and feel fortunate that I didn't have professors of his ilk during my engineering program at Case Western. They were content to use definitions that were consistent with the rest of the engineering community.

Although I know this thread is a complete waste of time I can't seem to ignore it. It's like driving by a car accident. You don't really want to see the carnage but you have to look. On with the carnage...

Don
no
i use teh word peak as all dictionaries and 99% of the world does

the few who erroneously use it as audio jargon are the ones claiming everybody else is wrong
Old 19th September 2011
  #355
Lives for gear
 

Quote:
Originally Posted by bdenton View Post
Let me state outright that I have absolutely zero knowledge of this subject (which is why I'm reading this thread, to learn something).

But you don't have to be very smart to look at the drawing and wonder: Could not the "inter sample peak" just as easily be an "inter sample dip"?

After all, it occurred between samples, i.e. it was not sampled.

While it would admittedly be highly unlikely that a dip of any significance could occur in such a small "slice" of time, there must be some interpolation going on...
it could be
nobody cares about dips
they dont cause problems

the peaks (but not *INTERSAMPLE* peaks as they do not exist) can cause problems in badly designed systmes
Old 19th September 2011
  #356
Lives for gear
 

Quote:
Originally Posted by narcoman View Post
!!!!! that's a pretty odd one!

!!!!

Don't know how many times one has to tell you that the reconstructed signal does not peak at the samples!


eh? That doesn't even BEGIN to make any sense!


Correct . It's called an inter sample peak. Higher... higher than? higher than the neighbouring samples. Sort of a "peak" if you will, between the samples. Sort of "inter" yes?heh

And as an "inter sample peak" it addresses some of the issues that happen when we re-construct signals.

I'll find you a nice picture then I'll give up


Here we go.... I know it's not ideal but it'll suffice to illustrate what we're all talking about. I'm convinced that you're thinking of something else....

Look at the nice picture of a very small window of a waveform. Now look at the four sampled points (let's ignore quantisation for now but assume it's nicely dealt with). I draw your attention to the two middle points. Look at the peak between the points. It's a specific voltage not sampled by the time domain samples BUT it doesn't matter. The waveform is correctly sampled EVEN though there is a peak in the waveform between the sample points. This peak is completely and 100% re calculable within the digital domain if we so wish. It's also correctly reconstructed when we go DA. It's a peak that happened between the sample points, it's a peak that is mathematically maintained such that a proportionally correct waveform results from the sample points.

sort of is like a little bit pregnant or almost dialing a phone nr.

the picture is meaningless
you are mixing the digital and analog domains again
and doing it wrong
Old 19th September 2011
  #357
Lives for gear
 

Quote:
Originally Posted by doug hazelrigg View Post
Maybe I shouldn't psycho-analyze OAG, but it appears he's backed himself into a corner of an untenable position and at this point has no choice but to fight, perhaps "to the death." Funny, I've been there myself. I don't think he's a troll, but I DO think we should stop feeding him

I'm just glad somebody has asserted that 4 samples are required to reconstruct a wave, instead of just 2, as is popularly asserted. ask anybody who has designed a plug-in that employs oversampling about this!
rotflamo

not in a corner

nr of samples depends on teh bandwidth being limited

you cant reconstruct anything meaningful from 4 samples
even worse if the signal was not band limited

here are 4 samples
0 0 0 0
whatcha going to recreate ?
Old 19th September 2011
  #358
Gear Nut
 

Quote:
Originally Posted by oldeanalogueguy View Post
it should be because it is flat out wrong
any chip without headroom was badly designed
been saying that all along
Nevertheless, these badly designed circuits are not uncommon, integrated or discrete. This 10 year old paper by T.C. Electronics engineers details 7 consumer CD players from NAD to Sony and shows the distortion caused by intersample-peaks:

http://www.tcelectronic.com/media/level_paper_aes109.pdf


BTW, have you read any of the linked papers or looked at any of the diagrams posted here? I notice that you don't comment on them at all.


Quote:
yes!! if you are worried that the digital will cause the d/a to have problems then you should attenuate it.
you lose nothing as you still get all the analog you ever had but minus the clipping distortion
Whoah - surprising - I concur.



It's over?




No more debate?








Old 19th September 2011
  #359
Lives for gear
 

Quote:
Originally Posted by psycho_monkey View Post
Well of course there is. You agree a standard! Same way we all drive on one side of the road in a given country...I can take my session from one studio to another, and provided the converters are lined up the same, my gain staging will be the same.

You really are trolling now aren't you? It can't possibly be that you don't grasp this basic concept.
nobody agrees on standards
there are bazillions of them
and companies ignore them all the time when it benefits them
others ignore them to achieve better results
Old 19th September 2011
  #360
Lives for gear
 

this guy understands why intersample peaks is meaningless jargon

Quote:
Originally Posted by theblue1 View Post
[bold added to reflect the bolding that OAG did when he quoted this in his post below]


Would it have made you feel better if the bolded bit had instead read, When a DA converts the stream of data into a smooth voltage variation WRT time some of those voltages will be higher than the [voltages generated from] preceding and following samples... ?


You know, I've read a lot of your writing on this issue and I'm still not entirely sure -- do you acknowledge the phenomenon but are quarreling with the descriptive terms of art used? Or are you suggesting that the scientists and design engineers describing this phenomenon are imagining it?
finally
somebody stated the issue properly

yes that happens as described
but they are not intersample peaks

they are the correct voltages per nyquist
nothing has peaked inter-samples

i am basically saying that the sort of terms mixing digital and analog signals like saying intersample peak are erroneous
and if you think they are true then what they claim does not exist (because the terms are misused, andor meaningless)

you have to mix the analog and digital domains to even come up with intersample peak

now can you also get peaks or other problems due to badly designed d/a but that is not intersample peak problems either
Post Reply

Welcome to the Gearslutz Pro Audio Community!

Registration benefits include:
  • The ability to reply to and create new discussions
  • Access to members-only giveaways & competitions
  • Interact with VIP industry experts in our guest Q&As
  • Access to members-only sub forum discussions
  • Access to members-only Chat Room
  • Get INSTANT ACCESS to the world's best private pro audio Classifieds for only USD $20/year
  • Promote your eBay auctions and Reverb.com listings for free
  • Remove this message!
You need an account to post a reply. Create a username and password below and an account will be created and your post entered.


 
 
Slide to join now Processing…
Thread Tools
Search this Thread
Search this Thread:

Advanced Search
Forum Jump
Forum Jump