Debate Thread: Scott's Hi-res Audio Test - Page 19 - AVS Forum
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post #541 of 2920 Old 06-12-2014, 11:00 PM
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Originally Posted by koturban View Post
Since you have yet to prove this level of jitter can be heard,
He probably knows that it can't be heard. That's why he uses things other than that in his sales pitch. Think about it, if you are a salesman trying to sell audio electronics and have a solid evidence (level matched DBT) that confirms the audibly superior performance of higher priced items, would you not use it in your sales pitch?
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post #542 of 2920 Old 06-13-2014, 01:57 AM
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Originally Posted by amirm View Post
Instead of the AVR attempting to extract clock timing from its HDMI input and drive its DAC, it instead creates its own clock and tells the source to follow it.
In pro-audio equipment this is rather common practice. I bought my Prism DA in 1996 and it has a "master clock" mode where the DAC runs at its internal clock and external equipment has to be slaved. Most professional digital equipment accepts external sync but afaik the majority of consumer equipment doesn't. This method works great when you keep the sampling rate constant (no problem in the studio). But for a consumer playing different formats, the DAC would have to adapt its clock to the source rate, which is probably not instantaneous and might become annoying.
Note that even in master clock mode there will be some jitter, but with a competent EE designer it won't depend on the source and interface
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post #543 of 2920 Old 06-13-2014, 03:39 AM
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Originally Posted by amirm View Post
Quote:
Originally Posted by arny

The source of the jitter is the multiplexing of audio and video that is inherent in the design of a HDMI link. HDMI is basically a serial link and all audio and video undergoes what is known as time division multiplexing. That means that the audio shows up in fits and spurts. It is up to the subsequent circuitry to erase as many artifacts of that fits and spurts process disappear below the threshold of audibility as it needs to. I know of no reliable evidence that there is a design failure here.

...this is not remotely correct. Here is a close analogy: when you write a file to disk, the operating system divides it into chunks called blocks. A common block size is 4 Kbytes. That means a 4 Megabyte audio file will have 1000 such blocks scattered throughout the hard disk. Yet when you play that music file, you don't notice that at all. Indeed you can make 50 copies with each one scattered differently and they all play the same.

Likewise when you stream audio over your Ethernet network, it has a maximum segment size of about 1,500 bytes. Anything larger such as the above 4 K blocks must be divided into segments. The Ethernet driver at transmit end does this and sets a flag in each packet, telling the receiver that they are part of a larger packet. The receiver sees the same and assembles them back to the 4 k block (this is all assuming you are not using large segment size). None of this packetization does anything at all to introduce distortions in the output of your music device. It is all upstream, digital in nature, and hence will not impact the analog output of the DAC (there is a remote aspect of this where the noise can bleed into the DAC differently but let's not get into that for now).
Inability to separate causes and effects from each other noted. All of the above are potential sources of jitter, but the degree to which that jitter is actually manifest of course varies. Just because the effects are more effectively dealt with in some cases doesn't mean that the cause doesn't exist.

Also some very basic differences between HDMI and the other situations are being ignored. HDMI is a synchronous protocol while disk I/O and network traffic are asynchronous. Both HDMI and S/PDIF are synchronous but S/PDIF transmits audio data continuously, while HDMI while also synchronous transmits audio data intermittently.

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post #544 of 2920 Old 06-13-2014, 03:42 AM
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Originally Posted by spkr View Post
He probably knows that it can't be heard. That's why he uses things other than that in his sales pitch. Think about it, if you are a salesman trying to sell audio electronics and have a solid evidence (level matched DBT) that confirms the audibly superior performance of higher priced items, would you not use it in your sales pitch?
Amir has had the same opportunity to do his own listening tests and prove that HDMI jitter can be heard. I offered him the opportunity to download files from this location https://www.dropbox.com/sh/0ov07gu5a...o9G4MUCm_6kMPa that have HDMI jitter at various levels from totally audible to far less. All he has to do is download FOOBAR2000 and its ABX plug in and press a few buttons.
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post #545 of 2920 Old 06-13-2014, 03:51 AM
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Originally Posted by amirm View Post
At the risk of creating more unrest , here is the Audio Engineering Society report on HIGH RESOLUTION AUDIO: http://www.aes.org/technical/trends/report2012.pdf
Co-chairs:
Vicky Melchior and Josh Reiss, Chairs

HDMI, the point-to-point connector required for BR and HD video, has excellent bandwidth and an Ethernet data link (HDMI 1.4), but lacks an audio clock. HDMI receivers must derive audio word clock from the video pixel clock, commonly resulting in very high jitter that affects quality and can be audible. Some high end receivers address the jitter and many companies are researching it but current solutions are expensive and uncommon.
The above is not an official AES peer reviewed publication. It even contains some technical claims that are adverse to some of Amir's recent postings:

"The point-to-point connector required for BR and HD video, has excellent bandwidth and an Ethernet data link (HDMI 1.4), but lacks an audio clock. HDMI receivers must derive audio word clock from the video pixel clock, [U][B]commonly resulting in very high jitter that affects quality and can be audible."

According to Amir streaming audio and audio base on disk files lack jitter:

"...this is not remotely correct. Here is a close analogy: when you write a file to disk, the operating system divides it into chunks called blocks. A common block size is 4 Kbytes. That means a 4 Megabyte audio file will have 1000 such blocks scattered throughout the hard disk. Yet when you play that music file, you don't notice that at all. Indeed you can make 50 copies with each one scattered differently and they all play the same.

Likewise when you stream audio over your Ethernet network, it has a maximum segment size of about 1,500 bytes. Anything larger such as the above 4 K blocks must be divided into segments. The Ethernet driver at transmit end does this and sets a flag in each packet, telling the receiver that they are part of a larger packet. The receiver sees the same and assembles them back to the 4 k block (this is all assuming you are not using large segment size). None of this packetization does anything at all to introduce distortions in the output of your music device. It is all upstream, digital in nature, and hence will not impact the analog output of the DAC (there is a remote aspect of this where the noise can bleed into the DAC differently but let's not get into that for now).
"

But they are also lack an audio clock that is transmitted from the source.

Just goes to show that you can find some pretty gross technical errors in high places, I guess.
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post #546 of 2920 Old 06-13-2014, 04:30 AM
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Originally Posted by amirm View Post
That's right. The feature actually exists in HDMI and is called ARC (not to be confused with Audio Return Channel). But it is hardly implemented and when it is there, it is stated as only work with the manufacturer's own gear. If it were broadly available this conversation would be moot .
It's unfortunate from the consumer's POV that one is obligated to be locked in to the specific manufacturer but I can understand how a manufacturer would like to squeak out one more sale. Some questions though.

For products that don't implement this approach, you said earlier that the jitter performance will be tied to the source's jitter. If that's the case, would the net jitter be somewhat of an additive thing where the jitter of the receiver is always increased?

Does this slaving have any negative consequences that would be objectionable? For example, would there be any delays?

When you showed the side by side graph of the Pioneer receiver operating in two modes, the jitter for the worst case is about 1.5 ns. That's still well under the level that would be detectable using according to the study by Benjamin & Gannon. So, while we can all acknowledge and tip our hats at an approach that lowers jitter into the low ps range, practically it doesn't seem that big a deal other than a weapon marketing can take out to try and drive more sales.

You've illustrated how your 12 year old DAC has killer jitter numbers. If one can buy a more recent DAC which has 10x or more less jitter and costs 10x less if not even lower ought it not be downgraded?

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
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post #547 of 2920 Old 06-13-2014, 05:02 AM
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Originally Posted by RobertR View Post
Engineers don't decide something is a good design by just "looking" at it. They test it to see if it meets the design goals. In this case, the test is to see how it sounds. Of course, you waved away the whole question of whether it makes an audible difference, thus revealing your priorities.
Agreed.

I really don't know how someone obtains an engineering degree without being taught about the fact that with engineering critical benefits such as sound quality, fuel economy and safety come first.

Overbuilding conflicts with critical performance goals in many situations. For example, an overbuilt building can't have as many floors and an overbuilt bridge can't span the river at hand. An overbuilt piece of audio gear can't reach as large of a market segment.

This is all pretty ironic coming from someone whose name is inextricably linked with a failed technology called HD DVD that was largely justified on cost savings.

Can you have too much ice cream?

"...with this post, I am announcing that I am no longer managing HD DVD development at Microsoft!"

http://electronics.howstuffworks.com/hd-dvd4.htm
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post #548 of 2920 Old 06-13-2014, 05:12 AM
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Originally Posted by amirm View Post
You said your manufacturer has used listening tests to verify the performance of your audio gear. Do you agree that no such test was performed by them?
I said the engineering criterion would be whether it makes an audible difference instead of how "impressive" it "looks" to another engineer (which you said is YOUR criterion). When talking to Arny, you waved off the whole question of audibility for designs YOU like, but then you agreed that would be "the test" when talking about designs you DON'T like. You're SO "flexible" about what's important to you, depending on what you're defending.
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post #549 of 2920 Old 06-13-2014, 06:13 AM
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I said the engineering criterion would be whether it makes an audible difference instead of how "impressive" it "looks" to another engineer (which you said is YOUR criterion).
Exactly. Here is an exact quote of what you actually said.

Quote:
Originally Posted by robertr
Debate Thread: Scott's Hi-res Audio Test

"Engineers don't decide something is a good design by just "looking" at it. They test it to see if it meets the design goals. In this case, the test is to see how it sounds. Of course, you waved away the whole question of whether it makes an audible difference, thus revealing your priorities."
Welcome to AVS where what you said and what you are quoted as saying often become two very different things.

Quote:
When talking to Arny, you waved off the whole question of audibility for designs YOU like, but then you agreed that would be "the test" when talking about designs you DON'T like. You're SO "flexible" about what's important to you, depending on what you're defending.

If I had a nickel for every time this has happened. Fewer and fewer people seem to be getting distracted by this tactic.

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post #550 of 2920 Old 06-13-2014, 07:14 AM
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Originally Posted by arnyk View Post
Agreed.

I really don't know how someone obtains an engineering degree without being taught about the fact that with engineering critical benefits such as sound quality, fuel economy and safety come first.

Overbuilding conflicts with critical performance goals in many situations. For example, an overbuilt building can't have as many floors and an overbuilt bridge can't span the river at hand. An overbuilt piece of audio gear can't reach as large of a market segment.
I can just see amir coming up with a new aircraft design, with a conversation going like this:

observer: so amir, what were the test results of the flight of your prototype?

Amir: I don't need test results. In my book, all I needed was to show the design to another engineer. He was impressed by the use of titanium in the control yoke.

Observer: amazing that you didn't test the flight characteristics. What does a titanium control yoke have to do with that?

Amir: you have a lot of angst about high end aircraft design.
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post #551 of 2920 Old 06-13-2014, 07:39 AM
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Originally Posted by arnyk View Post
The above is not an official AES peer reviewed publication. It even contains some technical claims that are adverse to some of Amir's recent postings:

"The point-to-point connector required for BR and HD video, has excellent bandwidth and an Ethernet data link (HDMI 1.4), but lacks an audio clock. HDMI receivers must derive audio word clock from the video pixel clock, [U][B]commonly resulting in very high jitter that affects quality and can be audible."

According to Amir streaming audio and audio base on disk files lack jitter:

"...this is not remotely correct. Here is a close analogy: when you write a file to disk, the operating system divides it into chunks called blocks. A common block size is 4 Kbytes. That means a 4 Megabyte audio file will have 1000 such blocks scattered throughout the hard disk. Yet when you play that music file, you don't notice that at all. Indeed you can make 50 copies with each one scattered differently and they all play the same.

Likewise when you stream audio over your Ethernet network, it has a maximum segment size of about 1,500 bytes. Anything larger such as the above 4 K blocks must be divided into segments. The Ethernet driver at transmit end does this and sets a flag in each packet, telling the receiver that they are part of a larger packet. The receiver sees the same and assembles them back to the 4 k block (this is all assuming you are not using large segment size). None of this packetization does anything at all to introduce distortions in the output of your music device. It is all upstream, digital in nature, and hence will not impact the analog output of the DAC (there is a remote aspect of this where the noise can bleed into the DAC differently but let's not get into that for now).
"

But they are also lack an audio clock that is transmitted from the source.

Just goes to show that you can find some pretty gross technical errors in high places, I guess.
Hi Arny,

Is the Ethernet function of HDMI used to stream audio? *NM I just googled it and found it's a hack like the rest of HDMI and HDCP.

If we move HDMI off to the side: When you are streaming Audio in a common Server/Client scenario there is no audio data jitter to worry about since the nature of packet data is not a real time transfer.

So in that context Amir is correct. I'm just not sure what it has to do with HDMI and will await an answer.

I believe there is error in the Ethernet Frame size and the assertion that block data is scattered rather than contiguous (although it can be scattered). But those are fundamentally non-issues for the great majority of time.

An audiophile likes to talk about how much they spent and how good it sounds.

A DIY'er likes to talk about how little they spent and how good it sounds.


Last edited by Jinjuku; 06-13-2014 at 07:54 AM.
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post #552 of 2920 Old 06-13-2014, 08:21 AM - Thread Starter
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Originally Posted by RobertR View Post
I said the engineering criterion would be whether it makes an audible difference instead of how "impressive" it "looks" to another engineer (which you said is YOUR criterion).
Please forgive me for saying this but I am not interested in "engineering criterion" from someone who is not an engineer. Your doctor doesn't take such advice from laymen in his chosen profession. Let's not create an artificial bubble around us here that is devoid of realities of our life outside of the forum.

You have no idea what test have and have not been run in audio gear you bought. And you don't know how well its internals perform. Technical reviews of audio and video have a set of industry standard tests that we run. I have shown you those very tests. Those tests were published in an industry magazine which is read by countless manufacturers some of which advertise in that magazine. Not one of them called into the editor or me saying, hey, we design our gear to "what is audible." Please don't do any more of these measurements.

What protest you put forward as a layman to rescue your previous position in audio is not material. No more than me doing that in your line of work.

It is interesting how we seek "science" and "engineering" to shut down other people's claims regarding audio. But the moment we are on the witness stand, we all of a sudden become subjectivists: "I only trust listening tests." Well, which listening test of the type of distortions I have shown do you have a "peer reviewed" double blind ABX test for? None. Right?

Your belief then was formed out of what made sense to you reading forum posts. It gave you a platform to stand on that you thought was very stable and allowed you to argue with others. That platform is a good one. It is pretty solid. It simply is not as solid as you think. That's all.

But that is not enough for our camp. We want a black and white position so that we can dismiss any and all claims of audibility from the other camp. Anything short of that is unacceptable.

You keep asking for listening tests. Well, this is one that was presented:



How many pages were spent pushing back on that "proof" from Arny and crew? Heck, even Arny himself joined the band and tried to take away value from that test!!!

I have quoted fellow objectivist on this very topic but his message is too hard for us to take:

Quote:Originally Posted by terry j 

well, in that case let me thank you [Amir] for your contributions. I KNOW I could not have kept my patience as you have, let alone maintained a sense of humour! It's funny how hard *we* can go to maintain our rightness, and how quickly that line is crossed where we no longer wish to learn (despite our objections to the contrary) where we fight tooth and nail...usually because we know our position is so tenuous that the slightest 'loss' means the whole game is over.

FFS, Amir has sat here page after page and SHOWN how, and under what possible conditions jitter may be audible. Hey, if it were a cable debate, and we showed with maths and sims that there could not possibly be a difference, well that would have proved it no? So why the **** in an 'argument' where the shoe is on the other foot does it suddenly become irrelevant what the science says??

My take on what the fear might be is the worry of what might happen if we concede a point of argument. The 'other side' will drive a frickin lorry thru the door if we do. I mean, there only has to be ONE person who hears a power cord (for sake of illustration) in what seems to be a proper test and the whole frickin lot of the rest of them will claim it as proof that they too can hear it.

No they can't, 'one in a million' means just that. But we KNOW every single one of them thinks they can hear it, using that person as proof, and even less urge to test the truth properly. After all it has been shown. So, we had better clamp down HARD on the one ever coming out, if only to keep the lid on the rest.

So, move on to something far less controversial than PCs, but as long as it falls into audiofool territory we had better clamp down on that too. It is just safer that way, keep each and every genie in the bottle. So the need to put amir in his place, and keep the lid hammered on tight. Because the ramifications of this little argument go waaaay past it's tiny borders.

""Oh, but amir has not given any evidence of audibilty"" (apart from the science you mean? The science that would be perfectly acceptable in a different argument, that the one we are talking about???).


Be totally honest here. If he told you that he had found, to his satisfaction, that turning the front panel on and off on his thingamabob had an audible difference, would you accept that? What then his findings of jitter? We know you would not accept his results, the genie is too terrifying to contemplate.

So don't come back at me with 'amir has yet to show audibility' ok? It is a definitional thing you know. Some things, by definition, are inaudible.

Bit like cancer, it cannot be cured hence any cure of cancer is untrue (why we are always then exhorted to donate to cancer research is beyond me). All of you could be right, it may be completely inaudible. But you sure as hell have not shown it by your arguments. Unless 'nanah nanah nah' counts as an argument.


So the nanah nanah argument continues.

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post #553 of 2920 Old 06-13-2014, 08:37 AM
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Please forgive me for saying this but I am not interested in "engineering criterion" from someone who is not an engineer.
Who is this nonengineer you're talking about?

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post #554 of 2920 Old 06-13-2014, 08:47 AM - Thread Starter
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Originally Posted by arnyk View Post
The above is not an official AES peer reviewed publication.
Of course it is "peer reviewed." What I post is the position of AES technical committee. It is not something written by one person. Indeed it is far more "peer reviewed" than any paper given the fact that peer review for papers usually has a single person performing such a review versus a group of people.

Who has peer reviewed your position with respect to jitter and related distortions in AVR? Have you had a paper published with this opinion that was peer reviewed? Do you have relevant design experience as to know how HDMI works and doesn't work?

Quote:
Originally Posted by arnyk View Post
It even contains some technical claims that are adverse to some of Amir's recent postings:

"The point-to-point connector required for BR and HD video, has excellent bandwidth and an Ethernet data link (HDMI 1.4), but lacks an audio clock. HDMI receivers must derive audio word clock from the video pixel clock, [U][B]commonly resulting in very high jitter that affects quality and can be audible."

According to Amir streaming audio and audio base on disk files lack jitter:

"...this is not remotely correct. Here is a close analogy: when you write a file to disk, the operating system divides it into chunks called blocks. A common block size is 4 Kbytes. That means a 4 Megabyte audio file will have 1000 such blocks scattered throughout the hard disk. Yet when you play that music file, you don't notice that at all. Indeed you can make 50 copies with each one scattered differently and they all play the same.

Likewise when you stream audio over your Ethernet network, it has a maximum segment size of about 1,500 bytes. Anything larger such as the above 4 K blocks must be divided into segments. The Ethernet driver at transmit end does this and sets a flag in each packet, telling the receiver that they are part of a larger packet. The receiver sees the same and assembles them back to the 4 k block (this is all assuming you are not using large segment size). None of this packetization does anything at all to introduce distortions in the output of your music device. It is all upstream, digital in nature, and hence will not impact the analog output of the DAC (there is a remote aspect of this where the noise can bleed into the DAC differently but let's not get into that for now).
"

But they are also lack an audio clock that is transmitted from the source.
You are confusing topics Arny. What they say is 100% the same explanation I have given in this forum on countless occasions. You know that.

I post my answer above in regards to you saying:

The source of the jitter is the multiplexing of audio and video that is inherent in the design of a HDMI link. HDMI is basically a serial link and all audio and video undergoes what is known as time division multiplexing. That means that the audio shows up in fits and spurts. It is up to the subsequent circuitry to erase as many artifacts of that fits and spurts process disappear below the threshold of audibility as it needs to. I know of no reliable evidence that there is a design failure here.

Notice that nothing of what you say is reflected in the AES technical group report above. My answer addresses why your impression of HDMI is not correct. I further showed you measurement data that shows how excellent performance can be gotten from HDMI and the factor that you mention then, is without merit:



So in summary, the position of the High Resolution Audio committee matches what I have been saying. HDMI is prone to more distortion and it takes an excellent design such as above to deal with it.

As an aside, do you remember this very first interaction you and I had on topic of HDMI?

Quote:
Originally Posted by arnyk View Post
When it comes to issues like jitter on the audio signal, you can pretty much count on a HDMI-driven A/V processor doing the best possible job of buffering, reclocking and generally giving effective care to the audio signal.

Dedicated paths such as HDMI seem to be preferable to paths that are routinely shared like USB or computer networking. This does not mean that those approaches always sound inferior. It can all be very good.
Is that consistent with what you have written now in this thread? How come you did not mention all of these problems with HDMI then? Do you think HDMI is preferable to the other paths as you say above given the problems you have told us about?

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post #555 of 2920 Old 06-13-2014, 08:59 AM - Thread Starter
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I don't think that is accurate. My home network is using frames of 9K.
I covered that in my post. You only quoted one line out of that paragraph . Here is the full paragraph again:

Likewise when you stream audio over your Ethernet network, it has a maximum segment size of about 1,500 bytes. Anything larger such as the above 4 K blocks must be divided into segments. The Ethernet driver at transmit end does this and sets a flag in each packet, telling the receiver that they are part of a larger packet. The receiver sees the same and assembles them back to the 4 k block (this is all assuming you are not using large segment size). None of this packetization does anything at all to introduce distortions in the output of your music device. It is all upstream, digital in nature, and hence will not impact the analog output of the DAC (there is a remote aspect of this where the noise can bleed into the DAC differently but let's not get into that for now).

Notice the part that I have highlighted now. The default Ethernet MTU is about 1500 bytes. You can optionally use "jumbo frames" to increase that and one of the common values is 9K that you are seeing. For that to work, all devices must support that size and the option turned on. Not all switches and NICs support 9K although that is becoming increasingly common. My new HP laptop has jumbo frames disabled by default. Note also that jumbo frames are a feature of gigabit networks. It should not be turned on on 10/100 mbit networks. So there, you are dealing with the standard MTU of ~1500 bytes.

None of this is material to the argument at hand though. No matter which way you look at it, audio over Ethernet networks comes in "chunks" we call packets. It is the fundamental way networking operates. A media player playing a song coming remotely from a PC or NAS is receiving data that comes in these separate blocks. In that sense it is "much worse" than HDMI yet we can be confident that it does not introduce any of the problems Arny is imagining for HDMI. HDMI has problems but it is not due to it sending packets of audio data during each frame of view.

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post #556 of 2920 Old 06-13-2014, 08:59 AM
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It is interesting how we seek "science" and "engineering" to shut down other people's claims regarding audio. But the moment we are on the witness stand, we all of a sudden become subjectivists: "I only trust listening tests."
Stop with the obfuscation, amir. You know perfectly well that science uses DBTs to demonstrate the efficacy of things, and you also know that audio subjectivists routinely denounce such tests, as well as sometimes resorting to casting aspersions on scientists. Stop lumping things together.
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post #557 of 2920 Old 06-13-2014, 09:05 AM
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Is the Ethernet function of HDMI used to stream audio?
No, chunks digital audio and control information are packed up into packets that are time division multiplexed with the video information.

HDMI data is broken up into segments called periods:

http://en.wikipedia.org/wiki/HDMI

"HDMI interleaves video, audio and auxiliary data using three different packet types, called the Video Data Period, the Data Island Period and the Control Period. During the Video Data Period, the pixels of an active video line are transmitted. During the Data Island period (which occurs during the horizontal and vertical blanking intervals), audio and auxiliary data are transmitted within a series of packets.[64] The Control Period occurs between Video and Data Island periods."

Audio data is transmitted during Data Island Periods.

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*NM I just googled it and found it's a hack like the rest of HDMI and HDCP.

If we move HDMI off to the side: When you are streaming Audio in a common Server/Client scenario there is no audio data jitter to worry about since the nature of packet data is not a real time transfer.
Agreed. HDMI is a synchronous protocol while streaming audio transfer off of a hard drive use asynchronous protocols. Ironic that our HDMI critic currently seems to be saying that asynchronous protocols give no inherent advantages when it comes to jitter, when not that long ago he was promoting asynchronous USB protocols as the best thing since sliced bread for reducing jitter.

The story seems to change depending on the needs of the hour...
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post #558 of 2920 Old 06-13-2014, 09:11 AM
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Stop with the obfuscation, amir. You know perfectly well that science uses DBTs to demonstrate the efficacy of things, and you also know that audio subjectivists routinely denounce such tests, as well as sometimes resorting to casting aspersions on scientists. Stop lumping things together.
Agreed. The request is not for a subjectivist preferred sighted casual evaluation, but the objectivist-preferred DBT.

In the past Amir has tried to use his own sighted evaluations to support his exceptional audio claims on AVS, but AFAIK there are no instances where he actually performed a DBT. Yet instances of lip service to DBTs abound.
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My understanding is that modern OS's on a spinner will do a reasonable job of keeping the blocks contiguous to avoid head thrashing.
Modern OS's? Operating systems like Unix have had this feature for some 30 years (dating back to BSD 4.1c if my memory is right). Yes, the operating system will attempt to co-locate the blocks with respect to seek and rotational latency of the mechanical drive (SSDs are an entirely different ball game). But this does not mean that it is storing the data as one big block. Every block allocated to a file will still be a separate chunk and read requests are sent to the controller for each one of them.

Let's say the blocks are in one big chunk on disk which they aren't but let's assume that. When the operating system reads the file, it puts each (usually 4K) block in a different page in memory. They are not contiguously allocated at all. The blocks are then copied to the application's (virtual memory) space as it requests it. So yet again the data arrives in chunks.

Allocating and using blocks of data is the ABCs of computer system design. By itself it cannot and will not create any jitter because the transfers are digital to digital. The memory locations at the target position have no place to stuff any "jitter" timing variations. Jitter does exist by the way in the path between those two stores. The wires are "analog" in nature after all. But when the final outcome is digital in nature, that jitter is eliminated.

We talk about jitter with respect to DACs because when it gets created it drives the DAC clock as an analog value. We don't take the clock timing and store it anywhere. It is hooked up to a pin on the DAC and if we wiggle those pulses back and forth, it manifests itself on the analog output of the DAC as distortion.

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post #560 of 2920 Old 06-13-2014, 09:23 AM - Thread Starter
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Stop with the obfuscation, amir. You know perfectly well that science uses DBTs to demonstrate the efficacy of things, and you also know that audio subjectivists routinely denounce such tests, as well as sometimes resorting to casting aspersions on scientists. Stop lumping things together.
You are not reading what you are writing with an objective eye. Didn't you all denounce Arny's amplifier tests? Did it in any way change your position in audio?

There is no amount or evidence that will move you one millimeter from your position. Isn't that what you would say about the other camp?

I argue both camps and the similarities are striking. Take this example: you have presented no new data whatsoever to the conversation. Post after post is just argumentative hoping to win a point by just responding as you do. That is not how "science" is developed.

What science do you know that relies completely on "DBTs" and no other means whatsoever? When a drug trial goes on, do they not measure patient's health and progress? No blood work? No scans. They just ask 8 people if they got better or not and go ahead and put the drug in market? They don't, right? But somehow in audio you complain in post after post about measurement data. All you want is that 8 person DBT. Why do you ask for it? Because it is a debating tactic. You think if you ask for it, you prove something. That doesn't wash in real world and it shouldn't here either.

Let's see if your next post has something new.

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post #561 of 2920 Old 06-13-2014, 09:44 AM
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What science do you know that relies completely on "DBTs" and no other means whatsoever?
Strawman. No one said anything about relying "solely" on listening tests.

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post #562 of 2920 Old 06-13-2014, 09:49 AM
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Originally Posted by amirm View Post
You are not reading what you are writing with an objective eye. Didn't you all denounce Arny's amplifier tests? Did it in any way change your position in audio?

There is no amount or evidence that will move you one millimeter from your position. Isn't that what you would say about the other camp?

I argue both camps and the similarities are striking. Take this example: you have presented no new data whatsoever to the conversation. Post after post is just argumentative hoping to win a point by just responding as you do. That is not how "science" is developed.

What science do you know that relies completely on "DBTs" and no other means whatsoever? When a drug trial goes on, do they not measure patient's health and progress? No blood work? No scans. They just ask 8 people if they got better or not and go ahead and put the drug in market? They don't, right? But somehow in audio you complain in post after post about measurement data. All you want is that 8 person DBT. Why do you ask for it? Because it is a debating tactic. You think if you ask for it, you prove something. That doesn't wash in real world and it shouldn't here either.

Let's see if your next post has something new.
No one is complaining about measurement data. It's the assertions you are trying make with them.

Reminds me of audio cable makers that tout reduced skin effect.
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post #563 of 2920 Old 06-13-2014, 10:35 AM - Thread Starter
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Strawman. No one said anything about relying "solely" on listening tests.
Well you did:

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Engineers don't decide something is a good design by just "looking" at it. They test it to see if it meets the design goals. In this case, the test is to see how it sounds. Of course, you waved away the whole question of whether it makes an audible difference, thus revealing your priorities.
You said "the test" is how it sounds. You left no room open for anything else. Specifically, you have done away with value of measurements. You have also done away with discussion of how the system works and how it can generate distortion. You have also done away with expert opinion on this matter as I post:

HDMI, the point-to-point connector required for BR and HD video, has excellent bandwidth and an Ethernet data link (HDMI 1.4), but lacks an audio clock. HDMI receivers must derive audio word clock from the video pixel clock, commonly resulting in very high jitter that affects quality and can be audible. Some high end receivers address the jitter and many companies are researching it but current solutions are expensive and uncommon.

You have no use for any of this when it comes to efficacy of design. You implied you were an engineer? Is this how the world turns in your specific profession?

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post #564 of 2920 Old 06-13-2014, 10:49 AM - Thread Starter
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No one is complaining about measurement data.
Really? I have spent a dozen post addressing such complaints.

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It's the assertions you are trying make with them.
I am not "trying" anything. Trying is arguing with words and no new data .

I have explained the technology, I have explained how distortion can be created. And shown measurements doing the same.

I have indeed characterized a PLL that does not filter audible jitter frequencies and indeed amplifies them is poor engineering. None of you presented a single bit of reference that says otherwise.

I get that you are uncomfortable with this data. If I had post countless times that digital audio is some kind of perfect technology and any and all executions of it in mass market products is just as perfect, I too would be worried about my "assertions."

That is a problem you all have created for yourselves. You believed what you have read online and ran with it and became a vocal advocate of it. A lot of what you believed *is* right. It just isn't as right as you think. Nor does the objective position go as far as you push it.

The objective thing would be to either accept the new data and change your views, or present contrary evidence. Neither you nor Robert do that in any of your posts. They are all information free like this one.

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Reminds me of audio cable makers that tout reduced skin effect.
It should not remind you of that at all. The distortions that I am showing you are in audible frequencies. You really think Audio Engineering Society would take this position:

HDMI, the point-to-point connector required for BR and HD video, has excellent bandwidth and an Ethernet data link (HDMI 1.4), but lacks an audio clock. HDMI receivers must derive audio word clock from the video pixel clock, commonly resulting in very high jitter that affects quality and can be audible. Some high end receivers address the jitter and many companies are researching it but current solutions are expensive and uncommon.

If it were the same as cable skin effect arguments of audio cables?

So you see, even your argumentative posts don't hold up to scrutiny. You continue to believe what you believed no matter how much new information is presented to you. We constantly complain about the "other camp" yet we continue to act just like the people we don't like. We assume people in the industry know no more than us. We assume that we can dismiss data with just word arguments. On and on.

I asked Robert to come back with a post that had new information in it and he did not. I bet you won't be able to share any new information in your next post either. This is not how a conversation is advanced or a technical position defended.

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post #565 of 2920 Old 06-13-2014, 11:08 AM - Thread Starter
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Agreed. The request is not for a subjectivist preferred sighted casual evaluation, but the objectivist-preferred DBT.
No sighted test results were presented in this thread so not sure who you are arguing with Arny. Whoever it is, needs to have his (her?) hands slapped .

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In the past Amir has tried to use his own sighted evaluations to support his exceptional audio claims on AVS, but AFAIK there are no instances where he actually performed a DBT. Yet instances of lip service to DBTs abound.
Arny, I say this without any exaggeration: you are our teacher and master when it comes to DBTs. By your standards, we don't even exist let alone be in a position to present a personal DBT!

With that done away, you said a couple of months ago:

Quote:Originally Posted by arnyk 

I've also done thousands of DBTs and organized the execution of so many (probably > 100,000) that I can't count them.

We have now seen your amplifier test that said it "proved" amplifiers sound different in DBTs. Can you please point to one of the other 100,000 DBTs like that so that we can learn from it? Thanks a bunch.

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post #566 of 2920 Old 06-13-2014, 11:26 AM
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I covered that in my post. You only quoted one line out of that paragraph . Here is the full paragraph again:

Likewise when you stream audio over your Ethernet network, it has a maximum segment size of about 1,500 bytes. Anything larger such as the above 4 K blocks must be divided into segments. The Ethernet driver at transmit end does this and sets a flag in each packet, telling the receiver that they are part of a larger packet. The receiver sees the same and assembles them back to the 4 k block (this is all assuming you are not using large segment size). None of this packetization does anything at all to introduce distortions in the output of your music device. It is all upstream, digital in nature, and hence will not impact the analog output of the DAC (there is a remote aspect of this where the noise can bleed into the DAC differently but let's not get into that for now).
Hi Amir,

I think there is some disambiguation here. On reading "Likewise when you stream audio over your Ethernet network, it has a maximum segment size of about 1,500 bytes."

I just want the potential person not to come away with that as the take away. Just bringing some clarity.

The other potential confusing bit is the mentioning of 4K block on the HD and the network not using a large segment size. Some may not understand with out a bit more context as to what is 'a large segment size'.

I don't think the person reading, that isn't a computer person, would natively understand if you are talking about 4K HD block or 4K Ethernet packet.

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Notice the part that I have highlighted now. The default Ethernet MTU is about 1500 bytes. You can optionally use "jumbo frames" to increase that and one of the common values is 9K that you are seeing. For that to work, all devices must support that size and the option turned on. Not all switches and NICs support 9K although that is becoming increasingly common. My new HP laptop has jumbo frames disabled by default. Note also that jumbo frames are a feature of gigabit networks. It should not be turned on on 10/100 mbit networks. So there, you are dealing with the standard MTU of ~1500 bytes.
That is spot on and quality network gear is darn affordable. Great to delineate 10/100 from 1000.

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None of this is material to the argument at hand though. No matter which way you look at it, audio over Ethernet networks comes in "chunks" we call packets. It is the fundamental way networking operates. A media player playing a song coming remotely from a PC or NAS is receiving data that comes in these separate blocks.
Yep. Bluefox at Polk Audio looked at your WBF write up about PLL re-clock and buffering S/DIF and erroneously confused your statement about Re-Clocking and a Buffer on S/PDIF doesn't remove jitter to be equal to the buffer on a computer not being able to remove jitter. I don't think he is understanding the differences in Sync'd, A-sync, realtime and non-real time mechanisms. That is he believes a buffer is simply a buffer.

His last post is still insisting audio jitter from the Ethernet cable could happen.

Monk made a really great point and I'll be darned if I didn't try it out and it worked:

I spun up Media Monkey, started playing song, paused it. Disabled the adapter, and was able to pause/play/pause play!

An audiophile likes to talk about how much they spent and how good it sounds.

A DIY'er likes to talk about how little they spent and how good it sounds.


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post #567 of 2920 Old 06-13-2014, 11:28 AM
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Really? I have spent a dozen post addressing such complaints.


I am not "trying" anything. Trying is arguing with words and no new data .

I have explained the technology, I have explained how distortion can be created. And shown measurements doing the same.

I have indeed characterized a PLL that does not filter audible jitter frequencies and indeed amplifies them is poor engineering. None of you presented a single bit of reference that says otherwise.

I get that you are uncomfortable with this data. If I had post countless times that digital audio is some kind of perfect technology and any and all executions of it in mass market products is just as perfect, I too would be worried about my "assertions."

That is a problem you all have created for yourselves. You believed what you have read online and ran with it and became a vocal advocate of it. A lot of what you believed *is* right. It just isn't as right as you think. Nor does the objective position go as far as you push it.

The objective thing would be to either accept the new data and change your views, or present contrary evidence. Neither you nor Robert do that in any of your posts. They are all information free like this one.


It should not remind you of that at all. The distortions that I am showing you are in audible frequencies. You really think Audio Engineering Society would take this position:

HDMI, the point-to-point connector required for BR and HD video, has excellent bandwidth and an Ethernet data link (HDMI 1.4), but lacks an audio clock. HDMI receivers must derive audio word clock from the video pixel clock, commonly resulting in very high jitter that affects quality and can be audible. Some high end receivers address the jitter and many companies are researching it but current solutions are expensive and uncommon.

If it were the same as cable skin effect arguments of audio cables?

So you see, even your argumentative posts don't hold up to scrutiny. You continue to believe what you believed no matter how much new information is presented to you. We constantly complain about the "other camp" yet we continue to act just like the people we don't like. We assume people in the industry know no more than us. We assume that we can dismiss data with just word arguments. On and on.

I asked Robert to come back with a post that had new information in it and he did not. I bet you won't be able to share any new information in your next post either. This is not how a conversation is advanced or a technical position defended.
"No new data" indeed. How many more times are we going to see your colourful plots, and quotes from a thirty year old paper that Arny participated in?

Until you produce a credible DBT that directly tests your "measurements" you are pushing pseudoscience.
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post #568 of 2920 Old 06-13-2014, 12:46 PM
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You said "the test" is how it sounds. You left no room open for anything else. Specifically, you have done away with value of measurements.
First if all, you agreed that how something sounds is "the" test for an audio device. Except of course, when confronted with questions about the sound of one of your "superior" designs. Then you want to dismiss or minimize the importance of listening tests, as you're doing now. Second, it's nonsensical to claim that making how something actually SOUNDS the bottom line is the same as claiming that measurements have no value. If you tried to tell an aeronautical engineer that wanting to know how an aircraft actually flies means he places no value on measurements/calculations of lift, thrust, and drag, or that a mechanical engineer who tests the strength of a steel beam isn't interested in measurements of the modulus of elasticity of steel, they'd both laugh in your face. I'm laughing.

Every time someone asks you the simple question "how does it SOUND, Amir", you avoid it with measurement talk (measurements are a useful TOOL to achieve the design goal, NOT an end in themselves), or credentials talk, or silly strawmen. Just like you're doing now.

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post #569 of 2920 Old 06-13-2014, 04:13 PM - Thread Starter
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I am going to note that yet again you have provided no new information to the conversation. Just more verbal back and forth.

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Originally Posted by RobertR View Post
First if all, you agreed that how something sounds is "the" test for an audio device. Except of course, when confronted with questions about the sound of one of your "superior" designs. Then you want to dismiss or minimize the importance of listening tests, as you're doing now.
Not at all. I am trying to "minimize" a debating tactic that tries to dismiss any information that is not in your favor with the same line over and over again: "where is your DBT?" I am presenting measurements. And I am presenting system architecture. And I am presenting quotes from AES saying there is a fidelity problem with HDMI. You keep trying to change the topic with that DBT request as if we are two-year olds and can't see that tactic from a mile away.

I am an electrical engineer. My interest is to examine products from engineering point of view and assess their quality. I don't just do that for you all. I do it in the process of qualifications for new lines/brands for Madrona Digital. I also do it to learn. I follow industry practices in this regard and write articles that get published in technical magazines with countless industry people reading them. I also share that information here. That you don't like it due to taking opposing stances here is not an issue for me or the rest of the forum.

You guys are used to throwing inaccurate technical claims to the "other camp" and see them back off because they are not technical. This is not proper. You need to at all times remain fair and objective. So I correct you. I know this is painful to take but it is the right thing to do.

I hope Arny forgives me for saying so but his explanation of HDMI operation couldn't be more wrong. He is saying a car is bicycle. He has read a spec, applied his personal interpretation to it and post it here as how HDMI works. Well, no, it doesn't work that way at all. We better get that straight in this thread and here before running off and lecturing the other folks on it. Otherwise you better get used to public embarrassment as someone like me catches you not knowing the letter B comes after A in English alphabet.

Going back to your DBT demands, where is *your* DBT? Arny says he has run 100,000 DBTs. Do you believe him? Do you believe he has run 1000? How about 100? 10? How many DBTs had you seen documented by Arny prior of the ones he has been involved in prior to me posting this amplifier one? Zero. Right? How come I was the only one interested in his DBT work if you all complete believers in DBTs?

Answer is that you don't question folks in our own camp. We have to stand united, and let the knowledge base of the forum be damned. I don't know how you can live with the optics of this looking so bad. And we call ourselves "objectivist?" That is an insult to the word if there ever was one. You can't be partisan this way and then use the word "science" in anything you say.

How many DBTs have you run that you have documented? Zero, right? What interest are you showing about DBTs? None, right?

Who here has documented DBTs related to this topic? None of the people arguing with me have run a single one I am sure or they would be presenting it by now.

So it is abundantly clear: I love to see a thousand DBTs on this topic. The more the merrier. I see value in all of them as I have shown in detailed analysis of the ones published. Let there be no doubt about that.

I don't see DBTs as a replacement for measurements. Measurements can pierce into design performances with a level of accuracy that DBTs cannot remotely duplicate. If you care about audio performance, you better care about measurements. The industry does. It is time for the vocal people in this forum to do the same.

So go ahead and let me know how your data differs than mine. Show me documented DBTs from any of you and that of Arny. That, would be something useful to talk about.
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post #570 of 2920 Old 06-13-2014, 05:40 PM
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A more careful reading from the AES does not say there is a fidelity problem, rather that there can be audible consequences with HDMI. If they'd said 'there are audible consequences' then I would agree with your words. Pity they didn't look to put a rough range of jitter that was the danger zone.

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