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44.1 vs 88.2 ABX report at AES
WernerO
post Mar 12 2014, 07:35
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QUOTE (C.R.Helmrich @ Mar 11 2014, 23:55) *
This might be a dumb question, but: How do you know this? Did you review the paper?


I read the paper. It states they used Pyramix 6. It does not state explicitly they used it for SRC. Hence the 'apparent' in my posting.

As others already said, there is no excuse for not using fully blameless SRC in this sort of exercises.

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C.R.Helmrich
post Mar 12 2014, 09:26
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QUOTE (WernerO @ Mar 12 2014, 07:35) *
I read the paper.

But I thought the paper hasn't been published yet... Are we talking about the same paper? The one for the upcoming AES?

Chris


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Arnold B. Kruege...
post Mar 12 2014, 13:13
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QUOTE (Kees de Visser @ Mar 11 2014, 09:28) *
QUOTE (Arnold B. Krueger @ Mar 11 2014, 13:44) *
Yeccch!
Are you sure ? I agree it's not state of the art anymore (Pyramix v.6 is an old version btw) and for this kind of testing there's no excuse for not using the best SRC available, even for DSD to 24/192.
The purple colour means the distortion products are around -120dBFS. You posted recently in another thread:
QUOTE (Arnold B. Krueger @ Feb 27 2014, 13:56) *
Seems to completely miss the point is that when measured performance is sufficiently high (e.g. the 100 dB rule) subjective tests are a complete and total waste of time.
I'd be interested to see more test details.



Yes, I spoke prematurely without understanding the true meaning of the color scale.

As you say, the test results show a bunch of inaudible artifacts, even though there are plenty of resamplers that are far cleaner.

The artifacts look to me like evidence of a process that was not adequately dithered.
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WernerO
post Mar 13 2014, 08:08
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Sorry, I referred to the original paper, in the subject title. Seems like I have been spinning around slowly.
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CherylJosie
post Jul 11 2014, 19:42
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Excuse me for beating this topic to death again? I just want to be clear. Feel free to ignore this comment if it is too long for you.

I am not sure anyone ever addresses sample rate vs. dynamic range independently of each other, and comprehensively, or even discusses the way that audio production might have theoretically distinct need for these two distinct benefits at each step.

I see that omission as a major flaw in the entire audio industry. Instead we see audio implemented with increasingly wide bandwidth and dynamic range as technology enables each to expand, all the way along the production chain from initial capture to final playback, while enthusiasts and detractors battle it out in the popular media.

This trend seems mindless to me. These two separate factors in commercial audio formats have historically been linked to the bleeding edge of technology with no regard for the actual theoretical limitations of the benefits of each variable in the audio realm.

Even more alarming is the trend in video standards. 'Nuf said.

Maybe the audio formats need to implement both bandwidth and dynamic range to the limits of technology in order to preserve economies of scale for instrumentation applications that might also need that format. Does that mean every application of the format must maximize both bandwidth and dynamic range simultaneously to their technical limits, including applications intended only for end-of-chain human consumption?

It is a simple matter to include in any media format specification a full matrix of bandwidth and dynamic range such that the flexibility of storage is maximized. Computer media standards are independent of data (except for specialized audio/video formats that computers are also compatible with) and already incorporate a full matrix of audio sample rate and audio dynamic range. The matrix of bandwidth and dynamic range is limited only by the computer's supporting hardware and software.

If a library of commercially purchased physical media is not similarly optimized it is wasteful and/or inadequate.

At the very least, the preservation of a standardized range of data formats on commercial media allows for the trading off of performance versus program length. Surely this is an advantage with little to no inherent cost penalty?

I guess now that the possibilities have been opened up for discussion it is time to narrow down the range of selections that make theoretical sense for audio production and distribution. I will start with bandwidth since that is the easiest to conceptualize.

Human hearing has inherent physical limitations to its bandwidth. These limitations are implicitly known and understood after decades of testing with sensitive instrumentation. The limitations are tested from inaudibility up to beyond the threshold of pain in the laboratory equivalent of a soundproof high power home theater.

People suffered in the service of science when those limitations were first characterized. Any discussion of enhanced bandwidth for audio begs the question if it is worth the pain, because the only way any human can perceive the bandwidth that extends into the threshold of pain is if it is accompanied by suffering.

Who would reasonably go there, knowing that the experience will not only be painful, but also that their own hearing would be permanently compromised by repeated or perhaps even a single exposure to audible energy in such a band?

The question becomes even more poignant if we take into account the fact that most of the human population has not even a transient opportunity to experience the full spectrum of such joys, since average hearing falls short of optimal hearing. At some point, the bounds of reason are violated.

My own theoretical understanding of the state of the art in audio is that the bandwidth of human hearing is the only relevant limitation to the bandwidth of commercially released digital audio recordings. Either 44.1KHz or 48KHz oversampling converters already exceed the bandwidth of human hearing. Commercial formats that include ultrasonic bandwidth add nothing of value to audio.

Ultrasonic bandwidth is interesting for instrumentation, but when present in the home or professional audio realm, ultrasonics merely generate intermodulated difference frequencies that shift down to audio frequencies in the output of an analog power amplifier.

The addition of audible distortion is not a benefit to audio, period. No manufacturer is reasonably going to develop a wide-bandwidth instrumentation-quality audio power amplifier to drive your super-tweeters simply so that Fido can hear undistorted dog whistles at the delivery deadline for your next beer from the ice bucket. Ultrasonics have no place in human audio. Only dogs will benefit from ultrasonics. Is Fido worth the wasted resources?

I know of no jitter advantage or any other audible advantage that is even a weak function of bandwidth.

All further remarks are completely independent of the question of the benefits of ultrasonic bandwidth on either a theoretical or a practical level and they must be addressed independently of ultrasonic bandwidth.

Now I wish to address dynamic range. Here again, the question asked must be separated into two components: the production process of a commercial recording versus the final delivery format.

Dynamic range is a fancy term for signal-to-noise ratio. The more noise in each individual signal, the more noise in the final product and the less dynamic range it will have. At some point called the noise floor, the relevant signal content becomes buried in the noise and at that point the signal is either perceptibly contaminated or completely inaudible.

It is important that all audible components of a program should be preserved at every stage in the production regardless of their relative energy content. They must all be maximally preserved in the production process because it is impossible to know in advance which components will ultimately be present, enhanced, or filtered out in the final product.

When the final product is complete, some components will be audible and others will not. At that point, the inaudible components may be safely discarded for economy in the final product while losing nothing at all of value to the listener. In some if not all final mixes, the final s/n of the final product is probably below that of even 'low-res' media anyway due to the combination and modification of all the input sources, some of which are probably low-res and/or noisy initially anyway.

Maybe someone who samples commercial recordings for incorporation into derivative works might benefit from the extra dynamic range of high-res final product. Short of the sampling artist and possibly instrumentation applications, no one else will benefit from dynamic range that exceeds the limits of human hearing in a final product that is distributed on audio-only media.

There is one possible exception of the sound algorithms in receivers that synthesize surround channels from a program. Any benefit of more bits is probably inaudible at that late processing stage anyway. (Is it? Who cares?)

Even if one wants to experience levels beyond the threshold of pain to marginally increase the audible bandwidth, such person will experience immediate and possibly permanent reduction in acuity at the threshold of audibility way down at the other end of the range of hearing, making such excessive dynamic range useless for the purposes of actual listening.

Linking bandwidth and dynamic range as if they are the same thing is a theoretical mistake in the audio realm. They are not the same thing. Incorporating more of either one into the final commercial product with no regard for the limitations of hearing, technology, or increasingly scarce natural resources is folly.

The same independence applies to dynamic range of the final delivery format, taken distinctly from the dynamic range of the entire production chain up to (but not including) the removal of the unnecessary LSBs in the final product. These are also two distinct problems, with theoretically independent factors driving their distinct best practices.


High definition audio media format standards seem to universally incorporate both bandwidth and dynamic range enhancements with no regard to the theoretical and practical limitations of the analog hardware they attach to, let alone the bounds of human hearing or economic reason. They seem to be driven entirely by the bleeding edge of technology on all fronts and cost be damned, as if the final target of such media could somehow incorporate instrumentation hardware.

I cannot speak for anyone else but if I ever need to design instrumentation that depends on an audio storage format I will surely use a simple drive that works with a simple computer and not an audiophile-grade over-priced over-performing toy media format emanating from a black box with a remote control.

So much for my theoretical understanding. I guess I will pause at my understanding for a while and see if gored sacred cows fly at me from catapults. Anyone?


Regarding the study itself, I was obviously confused by the comments when viewed in light of my theoretical understanding that differs so obviously and frustratingly from current 'best practices'.

The first thing that confused me is, what question exactly were the researchers asking and did it make sense to ask it theoretically or should it have maybe been something else? The second is, did they answer any questions, raise any new questions, or was the whole study poorly designed?

Is it live or is it Memorex? This would be the case where we want to know if material sampled mixed processed and delivered at high resolution sounds better, or if the final down-conversion to low-res is audibly transparent. This is perhaps the easiest question to answer with commercially available formats so perhaps that is why it was asked.

IMO 'because it is there' is a better reason to do anything than 'because it was easy'. Converters are known to perform beyond the limits of hearing and the standard way to prove that is with instrumentation that also functions beyond the limits of hearing, otherwise there is no way to prove that what is being heard is a faithful reproduction because consensus relies on scientific testing.

The assumption of course is that the only difference between high-res product and low-res product is the final down-conversion. The study guaranteed this by design of the study using a single high-res source to generate a low-res copy?

Unfortunately, this is not the current practice of media distributors. The CD quality format is processed for broadcast to automobiles where dynamic range is useless so the recordings are compressed to make them sound better over the road noise. This enhances the marketability of artists.

The high resolution products are a combination of stereo and multichannel recordings with widely varying formats and their application is strictly for home theater or audiophile systems that have a demand based on the performance of the media rather than the performance of the artist.

So the study asked a question about the state of media that does not exist in practice, it completely neglected to isolate bandwidth from dynamic range, and it did not even address the finer aspects of the production process to see if current best practices as designed by audio production engineers are adequate and reasonable.

Multichannel audio was completely ignored. Is MPEG etc. acoustically transparent in commercial media also/not compared to HD-MA?

The study failed to ask any relevant questions at all except to verify hardware adherence to the theoretically inaudible difference between high resolution oversampling DAC versus low resolution oversampling DAC versus low resolution oversampling ADC, and it apparently did so in a room that was not soundproofed with listeners who had no hearing tests of any type and using a converter with audibly compromised performance as verified in specifications and/or instrumentation testing of the device itself and operating it in modes that are not necessarily optimal for the entire audio production and distribution chain.

Testing converters for their technical accuracy with human hearing is one thing, but doing it incorrectly with compromised hardware and uncharacterized humans in noisy rooms is something else entirely IMO.

The study also used a low-res source for comparison to a high-res source. I am not sure what the point of that low-res source is. What question does that answer? Is it intended to verify the necessity for more resolution in the production of a final product than in the delivery format of the final product? If so, how does this particular test accomplish that, given that the benefits are strictly in signal-to-noise ratio and that they may only be realized by applying mixing and processing to many discrete signals in a total production of a new product?


It seems obvious that extra bandwidth in commercial audio formats is stupid. Likewise extra dynamic range. I assert on a theoretical level so my assertion relies on an entire body of pre-existing science. Unless I have made a gross technical error somewhere, my assertions cannot be theoretically debated.

It seems to me that the correct A/D conversion mode for studio recording is 48KHz/24 bits and the correct delivery format for D/A conversion is 48KHz/16 bits. This places the actual theoretical performance at each stage of the audio production firmly within the bounds of theoretically reasonable necessity as well as relaxing the design space for frequency response of the actual implementations to the broad side of a barn including even eliminating the largely redundant sample frequency with the most demanding analog filter requirements. It also allows for the retention of all the additional high-bandwidth modes in hardware and media via firmware, so that all instrumentation converter applications remain within reach of design engineers.


It is important to know the question being asked by the study and the theoretical basis for the question in the first place. How can we intelligently discuss the study without first framing its questions in our (my? your?) current best understanding of reality?

The worst part of the whole question in the first place is how unnecessary the confusion really is, given that design engineers make this sort of trade-off evaluation every time they design a product. It is a cut-and-dry algorithmic process to evaluate human hearing and to develop instrumentation to accomplish the evaluation with. It has been done. It is over.

Just let a company advertise a product with 'only' audio bandwidth compared to one with 'true high definition' ultrasonic bandwidth that degrades the audio performance. See which one is deemed the 'inferior' product. It is a numbers game. Guys, didn't you get the memo? Size is not everything.
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Thad E Ginathom
post Jul 11 2014, 21:55
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QUOTE (CherylJosie @ Jul 12 2014, 00:12) *
I am not sure anyone ever addresses sample rate vs. dynamic range independently of each other, and comprehensively, or even discusses the way that audio production might have theoretically distinct need for these two distinct benefits at each step.



Yes, often, frequently, in depth and in detail. Does that invalidate the rest of your post?


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Mach-X
post Jul 12 2014, 03:57
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This could all be avoided if a CD sized, laser read analog format was created. Didn't laserdiscs use analog like an LP but read by laser? Then the only argument would be the best way to rip it..?
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splice
post Jul 12 2014, 07:09
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QUOTE (Mach-X @ Jul 11 2014, 18:57) *
This could all be avoided if a CD sized, laser read analog format was created. Didn't laserdiscs use analog like an LP but read by laser? Then the only argument would be the best way to rip it..?


Laserdiscs used PWM (Pulse Width Modulation) for video and FM audio. (Later discs had digital audio.) They weren't losslessly rippable.


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Mach-X
post Jul 12 2014, 20:14
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Well of course they weren't rippable, nobody had laserdisc drives in their pcs back then wink.gif
My point was about the feasability of a strictly analog disc format read by a fine laser such as bluray. Heck they could even do it dualdisc style with analog one side, cdda on the other, then put it in an oversized cardboard lp cover. Then everbody would be happy.
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CherylJosie
post Jul 14 2014, 01:41
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QUOTE (Thad E Ginathom @ Jul 11 2014, 12:55) *
QUOTE (CherylJosie @ Jul 12 2014, 00:12) *
I am not sure anyone ever addresses sample rate vs. dynamic range independently of each other, and comprehensively, or even discusses the way that audio production might have theoretically distinct need for these two distinct benefits at each step.



Yes, often, frequently, in depth and in detail. Does that invalidate the rest of your post?


For all the discussion that is allegedly going on about splitting bandwidth from dynamic range and applying both intelligently to consumer products, there seems to be no one at home in the technical standards committees with a voice in the matter.

I guess that was who I meant by 'anyone'; anyone that might actually have been able to put a stop to this madness before the train left the station.
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Arnold B. Kruege...
post Jul 15 2014, 14:47
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QUOTE (splice @ Jul 12 2014, 02:09) *
QUOTE (Mach-X @ Jul 11 2014, 18:57) *
This could all be avoided if a CD sized, laser read analog format was created. Didn't laserdiscs use analog like an LP but read by laser? Then the only argument would be the best way to rip it..?


Laserdiscs used PWM (Pulse Width Modulation) for video and FM audio. (Later discs had digital audio.) They weren't losslessly rippable.


http://en.wikipedia.org/wiki/LaserDisc#Recordable_formats

"The two FM audio channels occupied the disc spectrum at 2.3 and 2.8 MHz on NTSC formatted discs and each channel had a 100 kHz FM deviation. The FM audio carrier frequencies were chosen to minimize their visibility in the video image, so that even with a poorly mastered disc, audio carrier beats in the video will be at least ‑35 dB down, and thus, invisible. Due to the frequencies chosen, the 2.8 MHz audio carrier (Right Channel) and the lower edge of the chroma signal are very close together and if filters are not carefully set during mastering, there can be interference between the two. In addition, high audio levels combined with high chroma levels can cause mutual interference, leading to beats becoming visible in highly saturated areas of the image. To help deal with this, Pioneer decided to implement the CX Noise Reduction System on the analog tracks. By reducing the dynamic range and peak levels of the audio signals stored on the disc, filtering requirements were relaxed and visible beats greatly reduced or eliminated. The CX system gives a total NR effect of 20 dB, but in the interest of better compatibility for non-decoded playback, Pioneer reduced this to only 14 dB of noise reduction (the RCA CED system used the "original" 20 dB CX system). This also relaxed calibration tolerances in players and helped reduce audible pumping if the CX decoder was not calibrated correctly.
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2Bdecided
post Jul 15 2014, 15:08
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QUOTE (Mach-X @ Jul 12 2014, 03:57) *
This could all be avoided if a CD sized, laser read analog format was created.
Why would you want an analogue format? Encasing a reflective layer in plastic and reading it with a laser doesn't make the system perfect - ask any laser disc owner. Scratches would be audible. Pressing blemishes could be audible. Error correction would be impossible and imperfect error concealment would be the best you could do. Using FM helps in many ways, but brings its own problems.

"Ripping" them would be a digitisation process, not a 1:1 bit-perfect transfer process. Each "rip" would be different, just like each transfer of a vinyl LP is different. There's no way of accessing exactly what was pressed - such is the curse of analogue. That's why digital is a blessing!

btw, a (non-laser) analogue successor to vinyl records is...
http://en.wikipedia.org/wiki/Capacitance_Electronic_Disc

Cheers,
David.

This post has been edited by 2Bdecided: Jul 15 2014, 15:09
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2Bdecided
post Jul 15 2014, 15:15
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QUOTE (CherylJosie @ Jul 11 2014, 19:42) *
Even more alarming is the trend in video standards. 'Nuf said.
Given a suitable screen size and viewing distance, a human with normal visual acuity can see the benefits of more pixels. Wider colour gamut, higher dynamic range, and higher frame rate all bring easily visible benefits. I don't know why any of this should be "alarming". It's a much better use of technology than higher audio sample rates.

QUOTE
It seems to me that the correct A/D conversion mode for studio recording is 48KHz/24 bits and the correct delivery format for D/A conversion is 48KHz/16 bits.
You are preaching to the choir here.

Cheers,
David.
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Moni
post Jul 15 2014, 15:24
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QUOTE (Thad E Ginathom @ Jul 11 2014, 16:55) *
QUOTE (CherylJosie @ Jul 12 2014, 00:12) *
I am not sure anyone ever addresses sample rate vs. dynamic range independently of each other, and comprehensively, or even discusses the way that audio production might have theoretically distinct need for these two distinct benefits at each step.



Yes, often, frequently, in depth and in detail. Does that invalidate the rest of your post?


What might be more helpful is naming or linking a few.
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Mach-X
post Jul 15 2014, 16:06
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QUOTE (2Bdecided @ Jul 15 2014, 10:08) *
Why would you want an analogue format? Encasing a reflective layer in plastic and reading it with a laser doesn't make the system perfect - ask any laser disc owner. Scratches would be audible. Pressing blemishes could be audible. Error correction would be impossible and imperfect error concealment would be the best you could do. Using FM helps in many ways, but brings its own problems.

"Ripping" them would be a digitisation process, not a 1:1 bit-perfect transfer process. Each "rip" would be different, just like each transfer of a vinyl LP is different. There's no way of accessing exactly what was pressed - such is the curse of analogue. That's why digital is a blessing!


How is any of this different from a vinyl record? You forgot to include the part where I suggested it could be done dualdisc style...analog on one side for the nutjobs enthusiasts, digital CDDA on the other for the rest of us ease of use/1:1 ripping.

My whole point was mostly in jest, but now I think it could be really neat. Think about the ABX possibilities! Finally, assuming both sides used the same mastering the argument could be settled once and for all!
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2Bdecided
post Jul 15 2014, 16:31
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QUOTE (Mach-X @ Jul 15 2014, 16:06) *
How is any of this different from a vinyl record?
It's not. That's why it's a bad idea! smile.gif

QUOTE
My whole point was mostly in jest
OK, I thought you were being really serious.

Cheers,
David.
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