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Feeding time at the HA zoo - again. This time main course is "FLAC vs. WAV".

129.33.19.254
Posted on February 1, 2011 at 14:31:52
carcass93
Audiophile

Posts: 7181
Location: NJ
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 All kinds of experts weigh in on inaudibility of differences between the two. Suffering hissy fits in the process, as usual.

What I personally don't understand - why is it so difficult to realize that it's not the contents of the files that matters? NO ONE moves past the argument that no data is lost because of compression. NO ONE even mentions real-time processing and its implications.

Of course, the fact that no one there owns a system that can resolve those differences, doesn't help either. The same goes for lack of listening skills of any kind.

 

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Well if you didn't do a 'proper DBT'..., posted on February 1, 2011 at 14:50:40
Presto
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Posts: 6003
Location: Canada
Joined: November 10, 2004
 ...to prove otherwise I am afraid you are in violation of Section 7 Subpart B of the Hydrogen Audio Terms of Service.

"All subjective statements regarding sonics must be accompanied by 1 (one) original and 2 (two) copies of the final DBT test report, where, notwithstanding Section 2 subpart J, the report bears the stamp or insignia of a certified DBT testing agency as approved for such testing by the Hydrogen Audio acting Bored of Directors or, in the event of insurrection or politcal unrest, the acting branch of the Hydrogen Audio gestapo as provided for..." et cetera, et cetera, ad nauseum,

Yes, you must hand in your hydrogen tank and breathing mask at once.

NO HYDROGEN FOR YOU! ONE YEAR!

Cheers,
Presto

 

RE: Feeding time at the HA zoo - again. This time main course is "FLAC vs. WAV"., posted on February 2, 2011 at 00:20:49
soundchekk
Audiophile

Posts: 2440
Joined: July 11, 2007
 It's not just the 12 years olds.

I'm having the same discussions over at the Squeezebox forum with "experts" - mainly software programmers though (a very special breed).

On a Squeezebox system you can choose between server based flac decoding vs. SB Touch based decoding. Server based decoding can be regarded pretty much the same as offline decoding. The client won't be loaded with the decoding work. Whereby load is a relative term. It's more about sharing the processor/ram for separate threads. That's why you experience differneces also at low CPU utilization levels.

Guess what I advise - I advise to use server based decoding. And this
was not what Logitech designers and all other forum experts were recommending since quite some time.


The main problem with the majority of software programmers is that they don't see the (indirect) relation between HW audio layer and their software. They can neither trace or debug the effects on the HW side. In this case simply no effects can exist from their perspective.

 

RE: Feeding time at the HA zoo - again. This time main course is "FLAC vs. WAV"., posted on February 2, 2011 at 00:27:10
russell d
 I won't question your hearing but you're saying it's a good thing that your system can 'resolve' these differences? Sounds like you have a hardware issue :)

 

Guess what I advise - I advise to use server based decoding........, posted on February 2, 2011 at 04:39:37
Cut-Throat
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Posts: 18449
Location: Minneapolis - St.Paul Area
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 On the Squeezebox Touch, where do you indicate server based decoding? I want to check my setting.



 

RE: Guess what I advise - I advise to use server based decoding........, posted on February 2, 2011 at 05:16:48
soundchekk
Audiophile

Posts: 2440
Joined: July 11, 2007
My blog: chapter II. 1.1.1

 

Got it, thanks! - I had done this, but forgot where the setting was...........nt, posted on February 2, 2011 at 05:25:57
Cut-Throat
Audiophile

Posts: 18449
Location: Minneapolis - St.Paul Area
Joined: September 2, 2000
 nt



 

RE: Feeding time at the HA zoo - again. This time main course is "FLAC vs. WAV"., posted on February 2, 2011 at 09:10:45
rick_m
Audiophile

Posts: 6230
Location: Oregon
Joined: August 11, 2005
 "NO ONE even mentions real-time processing and its implications."

Well... Maybe it's a lot easier to believe (or even think of) if you've heard it. Years ago I was just starting to play with computer audio and accidentally discovered that there was a small but noticeable difference in sound between WMA lossless and WAV playing back on the same machine. I dinked around enough to determine that it was real and just figured that it was likely an artifact of using a fairly slow older laptop. Later I exchanged some posts with JJ (I think that's who it was, the moniker kept changing) he at first said I was imagining things. After awhile he came around and said my computer was no good. I'd consider that agreement! Software guys without much HW (or system) background often can't see beyond the code (aka forest for trees). The rest of the universe is just the firmament in which their stuff exists and isn't above their horizon. I could tell you tales...

WRT DBT's ('Da Big Tomato?) I rarely use them, since it's just a hobby for me if I can't clearly discern a difference between two states that's good enough. Naturally that's insufficient for a larger audience. Elevating them to a fetish is nuts but if my understanding of the origin of HA is correct, i.e. originally they were primarily focused on compression algorithms, then I can see how it could have become ingrained in their culture for good or ill. IMHO there is about the same difference between audio forums as there is between different churches of the same faith: a few different tenants and practices that may seem trivial to a casual observer but are big differences to followers. Viva la difference!

Regards, Rick

 

"have a hardware issue" - certainly. We all do., posted on February 2, 2011 at 09:33:26
carcass93
Audiophile

Posts: 7181
Location: NJ
Joined: September 20, 2006
 Let's assume for a second that your response wasn't a joke.

When it comes to a question "Why don't I hear differences others talk about", there are 2 options how to react:

- assume that your hearing is perfect, your system is perfect, and others are gullible/fantasizing/having hardware issues;

OR

- question your own hearing and system. Make sure the former is good, and take strides to improve the latter.

By good hearing in this case I don't mean "normal" for average person. It's common knowledge that most detectable differences, that affect soundstage, impression of "air" and so on, lie in high frequency range.

It's not that difficult - download free tone generator, make sure your sound card and headphones can actually reproduce frequencies up to 20 KHz (better 22-24), set volume to your normal listening level, and play tones between 18 and 22 KHz. I know what my results are, to not worry about it for the time being.

Regarding hardware - I thought that on this forum, most people understand implications of additional processing at real time. There are 3 basic options for playing FLAC (let's skip cliet/server variety a la Squeezebox for now):

1. Decoding real-time during playback;
2. Decoding and loading into memory 1st track before playing; decoding and loading into memory each subsequent track during playback of previous one;
3. Decoding and loading into memory whole album before playing.

Of these three, only #3 could theoretically sound the same as WAV.

Disagreements?

 

Ahh, so that's what DBT means!, posted on February 2, 2011 at 11:32:08
carcass93
Audiophile

Posts: 7181
Location: NJ
Joined: September 20, 2006
 I was convinced that first two letters stand for "Deaf" and "Bull" - just couldn't figure out the "T". None of my guesses - "Travesty", "Transvestite", "Tranquilizer", "Triumph", "Trap" - made too much sense.

It's all clear now.

 

RE: "have a hardware issue" - certainly. We all do., posted on February 2, 2011 at 11:39:14
Tony Lauck
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Posts: 13629
Location: Vermont
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 With cPlay FLAC decoding takes place a small fraction of the time. Thus 99% of the time there is no effect. With short tracks the decoding takes place at the start of each track, generally when the music is quiet, hence has no effect at all, so if there are differences, "Who cares?" With most computers you can watch the "disk" light which will tell you when the cPlay reloads are occurring and this will be a good proxy for when any FLAC decoding is underway.

Theoretically (your choice of word) all of these methods would sound the same if the DAC had excellent jitter rejection. There are two competing aspects of DAC design when it comes to audibility of jitter, the amount of rejection provided by the clocking and buffering on input and the quality and resolution of the actual conversion and analog output. Jitter will be obvious if the input circuitry is low quality and the converter and output circuitry is high quality. Jitter will be hard to hear if the input circuitry has high rejection. (I include the necessary power supply and power wiring in this category. If it's not separate from the output circuitry there won't be good isolation.) Jitter will also be hard to hear if the output circuitry is low quality. (One obvious example would be a well designed buffer and reclocker that feeds a DAC with a crummy local clock that has huge amounts of its own jitter all the time, and so will mask any benefits of a low jitter input signal.)

If you hear differences in transports with a DAC then you can conclude that something is wrong, i.e. not everything equally excellent. If you don't hear differences in transports it could be because your DAC is high quality or it could be because your system is low quality. (If music sounds great all the time, then you will know which category applies.)

It is also possible that EMI/RFI from a transport could couple into amplifiers downstream of a DAC. This may make comparisons difficult to conduct in the "ABX" mode where two transports are powered up. One way to test if this is happening might be to play a "better" transport through the system and then alternatively run an "inferior" transport with the DAC output signal going nowhere. This will make it possible to distinguish whether the "inferior" transport is polluting the sound through the signal cable to the DAC or through some other means such as power wiring.

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

Deaf But Trying? nt, posted on February 2, 2011 at 11:48:13
Presto
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Posts: 6003
Location: Canada
Joined: November 10, 2004
 nt

 

RE: "have a hardware issue" - certainly. We all do., posted on February 2, 2011 at 11:59:52
russell d
 No I wasn't joking. The data out of the PC is same as you say, if your DAC rejected jitter adequately you wouldn't hear any difference. That's a hardware issue.

 

Both you and Tony speak in terms of "ideal"., posted on February 2, 2011 at 12:15:19
carcass93
Audiophile

Posts: 7181
Location: NJ
Joined: September 20, 2006
 Non-existent ideal, I must add. There were multiple attempts to narrow it down to an existing product - all unsuccessful.

So, as I said, I do have hardware issue. What you must realize, is that you do, too.

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 2, 2011 at 12:58:29
russell d
 Nope. I don't hear a difference between lossless formats, I also don't hear a difference between files on wireless network, boot drive, memory stick etc. I still own an Apple Airport Express which managed a similar trick though granted it's a crap DAC so you couldn't really rule out a true lack of resolution in that case. I don't own one but I understand a Squeezebox with server-side file processing behaves similarly.
When was it decided that this was an impossible engineering feat?

 

Just for kicks - what are the reasons "experts" would not recommend server decoding?, posted on February 2, 2011 at 12:58:33
carcass93
Audiophile

Posts: 7181
Location: NJ
Joined: September 20, 2006
 I can think of couple of things only:

- insufficient bandwidth over WiFi;

- additional activity on client side, transferring larger amounts of data if uncompressed (but that's negligible, compared to actual decoding client-side).

What did the gurus come up with?

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 2, 2011 at 13:33:51
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 Right at this moment my biggest hardware issue is a big hole in the foam around my left woofer. I can see the solder terminals, the wires from the crossover and the voice coil wire. The bass drum in the RR Rite of Spring was the final straw that finished off my left woofer. The driver now audibly buzzes on bass notes near its resonance. When this happens the sound stage suddenly collapses. (In most cases this soundstage collapse is the audible indication of the problem. It appears before any obvious buzz.) I ordered two speaker refoaming kits last night.

Computer audiophiles who tweak their software to address jitter issues do so because they have software skills. Other computer audiophiles tweak the power supplies in their computers because they have hardware skills. But this is not ultimately the way to deal with this problem, if only because a 100% pristine signal at the computer end will be less than perfect after traveling down a cable to a DAC. The DAC has to have jitter rejection capability and in the end it is going to be much easier to provide this by careful circuit design, layout, power and packaging. It should be obvious that a DAC is a much simpler device than a computer system. The problem is that the high end DAC designers have yet to step up to this plate, which makes sense because their efforts were spent on getting a good clock architecture first. However, having invested their efforts to eliminate the theoretical transport jitter coupling they should be taking the next step and realizing this isolation in practice.


I have no doubt that it is possible to build a transport jitter proof DAC. The first step is to build a measurement scheme that works on the analog output of the DAC to detect the effects of jitter and other input corruption. The second step is to build a test transport with jitter injection capability. The third step is to use these two tools to address and solve the problem.


Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

Health Effects of unnecessary microwave WiFi radiation., posted on February 2, 2011 at 13:37:34
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
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 Less WiFi better than more. None (wired Ethernet) best.

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

No argument from me - you seem to agree that it DOES NOT EXIST., posted on February 2, 2011 at 13:52:36
carcass93
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Posts: 7181
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 Would I want something like that? Sure.

Do I believe something like that will be available soon, and at reasonable cost? Nope, I don't.

People don't seem to realize that "I can't hear differences between X and Y" is not equal to "There are no differences between X and Y".

When I hear something like "I can't hear differences, so my system must be perfect", my question is - can you reliably hear difference in fuse direction in every component in your system? No? Then I'm sorry, I don't think further conversation is going to be productive.

 

RE: No argument from me - you seem to agree that it DOES NOT EXIST., posted on February 2, 2011 at 15:10:17
russell d
 ####People don't seem to realize that "I can't hear differences between X and Y" is not equal to "There are no differences between X and Y".

Very philosophical. We'll be discussing just what exactly are 'X' and 'Y' next. What if they're both pizzas? What if one is delivered by car and the other stuffed sideways into the rucksack of a guy riding a donkey. Let's says it matters to you how these pizzas arrive so instead of leaving it to chance you just go to the place and pick them both up yourself. Are they going to be exactly the same? If they're different is it enough to worry about?

####When I hear something like "I can't hear differences, so my system must be perfect", my question is - can you reliably hear difference in fuse direction in every component in your system? No? Then I'm sorry, I don't think further conversation is going to be productive.

I'd agree.

 

Huh? Can't hear ya... did you say Deaf Butt Trying? N/T, posted on February 2, 2011 at 15:26:52
carcass93
Audiophile

Posts: 7181
Location: NJ
Joined: September 20, 2006
 N/T

 

Sorry, I can't hear too good and my system ain't resolving enough... (nt), posted on February 2, 2011 at 16:03:08
Presto
Audiophile

Posts: 6003
Location: Canada
Joined: November 10, 2004
 nt

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 2, 2011 at 16:20:19
rick_m
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Posts: 6230
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 "I have no doubt that it is possible to build a transport jitter proof DAC."

In that case you must already know the worst case limits of human sensitivity and are well positioned to write a useful specification of just how well a DAC must perform to insure that no one can hear any form of jitter artifact. Go for it, just remember that zero or infinite are limits, not thresholds.

"It should be obvious that a DAC is a much simpler device than a computer system."

Obvious to whom? Only to someone that's never worked with mixed-signal systems I'm thinking and I bet you have. Most parts of computers are ridiculously simple because they are designed to be. An artificial construct designed to be simple and forgiving. It hits the fan at the domain interfaces so the DAC's, ADC's, Head positioning servos, et al are where the action is. Oh, and software. We can't seem to get anything simple enough that programmers can't screw it up.

"The DAC has to have jitter rejection capability"

OK! We're there as they all have some. Next?

The problem with these wretched systems is that they are wretched systems, not wretched components of a well-defined system. If they interact with their own damn power cords enough to throw off the sound how can one expect them to communicate well amongst themselves at the signal level?

"The first step is to build a measurement scheme that works on the analog output of the DAC to detect the effects of jitter and other input corruption. The second step is to build a test transport with jitter injection capability. The third step is to use these two tools to address and solve the problem."

Hows about we figure out what the problem is first? We need to isolate the human with the keenest ability to sense jitter and either remove him from the gene pool or quantify his abilities. I doubt that it's a singular person, since there are several distinct artifacts going by the name of jitter there are likely several distinct best (worst?) case people in the world that can hear them. Quantify all of their capabilities and write a Spec. A SYSTEM Spec. that does not exceed any of their thresholds. Naturally it's crucial that they not be allowed to interbreed are we'll have to start over.

Yes, this is sort of tongue in cheek, but look at it this way, it IS possible to get software perfect to any arbitrary degree this side of infinity, that's why we now push what we can into the software realm. But even so it tends to be riddled with bugs due to human shortcomings. Hardware can NOT be made perfect, we deal with real stuff and signals and Brownian motion and cosmic rays and quantum effects and and and, human shortcomings ALSO.

"The problem is that the high end DAC designers have yet to step up to this plate"

Oh yes they have, they just aren't hitting home runs 100% of the time yet. Just looking at the materials available on-line I know that Ayre, Linn and Wavelength have addressed some of this fur sure and even in ways that I approve of. But do they know how good it has to be? Does anyone?

And it's not just jitter, it's everything. Home audio is a crap shoot, that's it's blessing and it's curse. And it's bizarre allure. If these systems worked reliably it would be great, but not interesting. We'd then be stuck just spending time enjoying music and our families...

Regards, Rick

 

"I don't think further conversation is going to be productive.", posted on February 2, 2011 at 17:35:09
RussD


 
Hearing the effects of fuses inserted "backwards"???

Me thinks you have a larger problem and it's not audio related.

 

CPU Load, posted on February 2, 2011 at 17:50:11
Scrith
Audiophile

Posts: 1169
Location: Los Angeles
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 If you are hearing an audible difference between FLAC compression levels on a computer manufactured in the 21st Century then you've got some serious audio playback software, OS, or Audio driver problems. Using audio playback software that supports a reasonable amount of buffering and/or forces audio data decompression to take place in its own processing thread might help alleviate these problems, however.

The idea that FLAC compression levels can influence the sound in a system that is in good working order is akin to saying that a book being read to an audience is better if it is printed in a larger font. As long as the reader is competent, the size of the font is irrelevant. :-)

 

It figures you'd be here soon enough. Soundchekk below ..., posted on February 2, 2011 at 20:09:29
carcass93
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Posts: 7181
Location: NJ
Joined: September 20, 2006
 ... gives pretty good analysis of what your, and the likes of yours, problem is.

I realize you're not going to start hearing better - but I would settle for you to at least start learning, instead of exposing your thoroughly irrelevant pseudo-knowledge at every corner.

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 3, 2011 at 00:12:57
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 Software on its own DOES not solve jitter issues. Jitter is a hardware and transmission issue.

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 3, 2011 at 00:16:21
fmak
Audiophile

Posts: 13158
Location: Kent
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 Then you don't have a system that resolves sufficiently, a problem with hearing, or a resolute believe that it cannot happen.

 

RE: "have a hardware issue" - certainly. We all do., posted on February 3, 2011 at 00:17:05
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 cPlay is hardly the best player!

 

RE: Feeding time at the HA zoo - again. This time main course is "FLAC vs. WAV"., posted on February 3, 2011 at 00:18:32
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 Agree, having quite a lot of work experience that way.

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 3, 2011 at 07:29:52
soundchekk
Audiophile

Posts: 2440
Joined: July 11, 2007
Find us the perfect DAC... ...pleeease!!!!

No more philosophical hot air talk. Get us facts on the table.


As long as there is no (affordable) perfect world interface to the DAC in place, SW and HW modifications on the transport will have an impact on the SQ.
It's that easy.

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 3, 2011 at 08:06:16
Tony Lauck
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Posts: 13629
Location: Vermont
Joined: November 12, 2007
 I would settle for any transport related variation in the analog output of the DAC being at least 20 dB below the noise level of the DAC. (That's noise, not noise plus distortion.) I am not shooting for impossibly low jitter out of the DAC, zero noise, zero distortion, or any other physically impossible design goals. I am solely focused on getting rid of any measurable or audible differences that result from different (but bit-identical) signals being fed to the DAC. The design I have in mind is modular and I expect it can be built up to provide any desired degree of attenuation if variations need be even further below the noise.

The whole point of this exercise is to make it unnecessary to treat the computer system as a mixed signal system. If the DACs provided adequate immunity then this would be possible. The fact that inmates hear differences and are tweaking their computers as if they were mixed signal systems makes my point. Due to the immense number of components and complex non-linear software controlled feedback loops in a computer this is a completely intractable problem. It's made even worse because most of the design information is proprietary. The only hope is to isolate the problem down to the relatively small number of components in a DAC, so that these can be properly optimized as a mixed signal system.

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

Yes - that sums it up pretty accurately., posted on February 3, 2011 at 09:20:05
carcass93
Audiophile

Posts: 7181
Location: NJ
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 Somebody HAS to call things as they are, even at the risk of backlash. I usually do.

 

RE: CPU Load, posted on February 3, 2011 at 09:45:25
Tony Lauck
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Posts: 13629
Location: Vermont
Joined: November 12, 2007
 "As long as the reader is competent, the size of the font is irrelevant. :-)"

Funny, that example. I recall being in just this situation one time, with inadequate borrowed reading glasses and dim light. I had to occasionally pause while I squinted to make out the letters. My audio output was jittered. :-)

FLAC (and all lossless CODECs) are variable bit rate. This entails a more complex buffering strategy than is needed for other real-time processing. Typically there will be a periodic burst of 100% CPU utilization while a buffer of FLAC is decoded. (Actually it's a bit more complex because FLAC comes in frames.) Depending on the amount of buffering used, these periodic spikes of activity can be seen by looking at graphs of CPU utilization, power supply rail voltage, and for large enough buffers, even CPU temperature and fan speed. (I have personally observed all of these variations.) The power supply rail voltage is probably the most relevant parameter and the variations will affect the clocks and other clock circuitry, and ultimately with DACs that have imperfect jitter rejection, the analog output signal. In some cases, these effects have been observed by measuring output spectra and correlating jitter peaks with system parameters.

The effects are real. Whether they are audible or not is a separate issue that depends on the DAC, the system, the listening room and the listener.


Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

Oversimplification., posted on February 3, 2011 at 10:53:40
carcass93
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Posts: 7181
Location: NJ
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 1. "... ultimately with DACs that have imperfect jitter rejection..." - no need for that, you could simply say "with DACs", or "with ALL DACs".

2. You make it sound like it's all about bursts of activity, while in reality it's just about activity - ANY processing, no matter how low its CPU utilization is, affects electrical activity (MB traffic), and ultimately sound quality.

3. It's even more than that - do the following simple experiment (I have):

Write an application, executable or Windows service, that does nothing, or polls timer every 10 minutes, so you know for sure that nothing happens in 10-min intervals, it just sits there occupying memory. To make effects more obvious, declare some buffer there, so it occupies more memory.

Compare sound quality with that application running versus not running. What do you hear? And why do you think you hear that? Is memory taken buy that app (very little!) affecting memory allocation used by media player?

It's the same effect as with disabling Windows services, only here you know for sure that app does ABSOLUTELY NOTHING.

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 3, 2011 at 10:55:47
russell d
 I can use the same DAC in adaptive instead of async mode and it will not only sound rather worse but it will also now magically reveal differences in bit-perfect data sources.
I thought you had or did have dCS gear so you know it has adequate resolution.

 

RE: Yes - that sums it up pretty accurately., posted on February 3, 2011 at 10:59:59
russell d
 Please see reply to fmak above.
Don't glamorise it as some sort of bold heresy, people may disagree with you because you're just wrong.

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 3, 2011 at 11:05:26
rick_m
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Posts: 6230
Location: Oregon
Joined: August 11, 2005
 "The whole point of this exercise is to make it unnecessary to treat the computer system as a mixed signal system. If the DACs provided adequate immunity then this would be possible."

Laudable goal! At least the path via the DAC should be achievable to the point of no audible differences in a given situation IMHO. I wonder how close extant designs are? I haven't looked at DAC's for a while but I recall being impressed with what I could glean from published information about the implementation in the Ayre and Linn units but since I can only afford to experience them vicariously and don't recall seeing any useful measurements or experiments I'll likely never know how well they actually do.

Unfortunately the mixed-signal system at hand extends to the whole audio system so while the DAC is likely the main problem I'd not exclude the rest out of hand. Controlling susceptibility (or emissions for that matter) doesn't seem to be a priority to most 'audio designers'.

Logically it's 'just' a matter of buffering and isolation. One limit always seems to me to be the designs that swallow all of the data prior to playing. After 'loading' my DAC I could an take my computer out and burn it and still play the music, now that's isolation! Maybe not the most convenient solution however...

There's so much to it, all things are never created equal. Heck, I love the sound of this laptop just using internal audio. But if I load the same music on the ipod nano that I now proudly possess I get worse sound, but great isolation! Actually it's only an article of faith that it's really playing the same data since I can't find a way to suck the data back out of the portable. Probably a DRM thing.

Regards, Rick

 

Sure. Or just because I'm right. N/T, posted on February 3, 2011 at 11:16:30
carcass93
Audiophile

Posts: 7181
Location: NJ
Joined: September 20, 2006
 N/T

 

RE: Both you and Tony speak in terms of "ideal"., posted on February 3, 2011 at 11:20:47
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 Well yes, the idea is not to just get equal sound from all transports. If that's all you want then you may as well replace your DAC with a brick. No need for an amp or speakers, either. :-)

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

Progress comes from appropriate simplification, posted on February 3, 2011 at 11:53:21
Tony Lauck
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Posts: 13629
Location: Vermont
Joined: November 12, 2007
 1. Perhaps there is a DAC out there that has excellent jitter immunity and still sounds good. There is no reason to believe that such a device is impossible, just not on the market yet.

2. I was citing one specific case that is unique to FLAC. Any activity has the possibility of changing things, but this one is sufficiently gross that it can even affect fan speed. :-)

3. Two possible reasons for the differences with your 10 minute task immediately come to mind:

First, the scheduling software in Windows may not be efficient, in which case every time the O/S checks what there is to do it has more work if there are additional possible candidates. (I don't know if that is the case with Windows, but it was definitely the case with other operating systems for their networking code.)

Second, when something is loaded into memory it will affect the location of other programs that are subsequently loaded into memory. The processing efficiency may be affected because two hot loops may be loaded in such a way that they are competing for the same cache line. The exact details will depend on the processor cache design and the order and size of memory allocations.

With proper instrumentation it would be possible to observe or eliminate both of these possibilities. Obviously, for best results you need separate test equipment to observe the operating system, as a measurement process in the system will itself affect what is being measured. Neverthe less it may be possible to ascertain what is going on by careful software implementation. One measurement of OS and CPU efficiency is system idle time for a given workload. However, you can't get this accurately using standard operating system measurement (e.g. Windows task manager). The reason is that the sample interval is probably correlated with operating system timer based functions. It may be possible to measure these effects by running a low priority CPU bound process in a "soak loop" and observing how system changes affect progress of this task. (Don't try this on a system that has minimal cooling.)

I'm sure there are more possibilities, these are just two of them. I think it is futile to attempt to optimize system software without having access, at minimum, to source code.

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

RE: CPU Load, posted on February 3, 2011 at 16:33:14
Scrith
Audiophile

Posts: 1169
Location: Los Angeles
Joined: July 19, 2005
 "My audio output was jittered."

This is a hardware problem. You need to replace your optical components with a newer model.

"Typically there will be a periodic burst of 100% CPU utilization while a buffer of FLAC is decoded."

You are seeing FLAC decompression cause a 100% CPU load on a modern, multi-core system? And the power requirements for this CPU load burst is causing the signal of your digital output (which is on a different power rail than the CPU, no doubt) to change? If so, I see two solutions: 1) player software that puts a reasonable limit on how much FLAC data it asks the FLAC library to decompress at a time (perhaps this idea of decompressing before playback into a large buffer, which seems a bit hare-brained in the first place given that CPU utilization for decompression during playback into reasonably sized buffers is trivial, is not such a good one?), 2) a CPU and/or power supply upgrade.

 

RE: CPU Load, posted on February 3, 2011 at 17:45:35
Dawnrazor
Audiophile

Posts: 12809
Location: N. California
Joined: April 9, 2004
 Hi Scrith,

Why are you such a hardcore flac addict?

Face it, Flac is not the holy grail for everyone. And it does mess up some systems, especially if you do realtime upsampling. Tony is right about the spikes. I had them with flac files.

Personally I would rather give up tagging and some disk space vs. having a 3+ ghz cpu with 16gb of memory and the fans that go with it.....

I know, bits are bits. But tell me this. Do software players sound different? Do different versions of them sound different??



Cut to razor sounding violins

 

RE: CPU Load, posted on February 3, 2011 at 18:26:00
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007
 At a certain age one wishes to replace one's entire set of hardware components with new models. :-)

100% instantaneous processor utilization for a period of time or 0% utlization. They are the only possibilities. A processor is either idle or fully utilized. (If I had a dual core system, the potential utilization would go up to 200%.) To talk about intermediate values you must result to averages, and for these statistics to be meaningful you will have to pick the appropriate time period for averaging. Someone skilled in the art of computer performance analysis would appreciate these facts.

Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

RE: Health Effects of unnecessary microwave WiFi radiation., posted on February 4, 2011 at 05:26:36
fmak
Audiophile

Posts: 13158
Location: Kent
Joined: June 1, 2002
 Sure, my satellite downlink (2150 GHz) affects my audio system adversely. I switch it off thru unplugging the always on lnb, or at the mains. The latter is a nuisance 'cause the thing then needs rebooting.

 

RE: Health Effects of unnecessary microwave WiFi radiation., posted on February 4, 2011 at 13:43:02
cpuaudio
 Best to don your tin foil hat - yours has antenna I hear.

 

Tin foil hats - virtual and real., posted on February 4, 2011 at 14:53:09
Tony Lauck
Audiophile

Posts: 13629
Location: Vermont
Joined: November 12, 2007



A picture of my "tin foil hat". Primarily used to avoid security intrusions, audio pollution and potential health effects. Below you will find a video about the real thing. :-)


Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

 

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