HydrogenAudio

Hydrogenaudio Forum => General Audio => Topic started by: icstm on 2012-02-17 15:25:22

Title: High Playback Sampling Frequencies
Post by: icstm on 2012-02-17 15:25:22
OK, at the risk of sounding completely stupid?

Why do people listen to music with high sampling frequencies?
What is 88k+ providing them?
I understand why you might record at a high sampling rate, but why keep that for playback?

Looking through the FAQ, there are threads from 2003 that point out that the sampling frequency and bit-dept work in tandem. So the quantisation error of 16bit at 44.1k has the opportunity to be corrected sooner at a higher sampling rate, so in some ways is like a dithering pattern.

However given noise introduced in the analogue systems required to listen to music, a SNR within a 16bit signal  of ~96dB seems pretty good.

So assuming that speakers struggle to produce the sounds that a 192k sampling frequency allow (eg 96kHz) and assuming that 16bits were sufficient when compared to the analogue equipment in the system, what have I missed in these high sampling playback formats?
Title: High Playback Sampling Frequencies
Post by: Prince Of All Saiyans on 2012-02-17 15:37:20
I'm not totally sure, but recalling my ever-so-tiny amount of knowledge pertaining to stereo CDs (44.1 khz, 22.05 khz per channel), I'd say the higher frequencies are for surround sound tracks or something of that nature.

Please correct me if I'm wrong, but I'm pretty sure humans cannot hear frequencies higher than around 20 khz.
Title: High Playback Sampling Frequencies
Post by: dhromed on 2012-02-17 15:51:07
what have I missed in these high sampling playback formats?


The economic benefits of selling people larger numbers for more money.
Title: High Playback Sampling Frequencies
Post by: pdq on 2012-02-17 15:52:54
People sell music with higher sampling rates for the same reason that they sell amplifiers whose volume controls go to 11, to make more money.

Edit: dhromed beat me.
Title: High Playback Sampling Frequencies
Post by: dhromed on 2012-02-17 15:55:35
I'm not totally sure, but recalling my ever-so-tiny amount of knowledge pertaining to stereo CDs (44.1 khz, 22.05 khz per channel), I'd say the higher frequencies are for surround sound tracks or something of that nature.


Surround sound is encoded in more than two channels, and all channels will be 16/44.1, or 24/48, etcetera.

The audio signal is the audio; it's not a carrier wave where extra content is somehow modulated into the higher frequencies. 
Title: High Playback Sampling Frequencies
Post by: Prince Of All Saiyans on 2012-02-17 15:56:58
Exactly. That's why you see headphones with frequency ranges all the way up to 50+ khz, among other things.

When you don't know the answer to a question, assume it's money. 


edit: Thanks for the info, dhromed. Didn't know that.
Title: High Playback Sampling Frequencies
Post by: greynol on 2012-02-17 16:19:04
stereo CDs (44.1 khz, 22.05 khz per channel)

The samplerate is 44.1kHz in order to properly preserve ~20kHz of bandwidth. It has nothing to do with it being in stereo.
Title: High Playback Sampling Frequencies
Post by: Prince Of All Saiyans on 2012-02-17 16:53:42
stereo CDs (44.1 khz, 22.05 khz per channel)

The samplerate is 44.1kHz in order to properly preserve ~20kHz of bandwidth. It has nothing to do with it being in stereo.


Got it. So back to the OP's question, since the frequency for 44.1khz or 48khz is per channel, even surround sound would be unnaffected by the higher frequencies of 96khz or 192khz. Right?
Title: High Playback Sampling Frequencies
Post by: pawelq on 2012-02-17 18:05:44
to stereo CDs (44.1 khz, 22.05 khz per channel)




It's actually 44.1 in each channel.



There is a slight and somewhat disputable evidence for minimal influence of frequencies above ~20 kHz on perception.


As others said, this mostly an advertising point, you can show that the numbers in your gear are higher than numbers is the other guy's gear.

Or in your brochures you can draw a smooth sine @192kHz and a (misleading and untrue) jagged sine @44.1k.

There are however people who are made very happy by this marketing phenomenon - I mean scientists who study audition using animal models. Most mammals' hearing range goes higher than human hearing range. 10 or 20 years ago getting  equipment capable of producing sounds up to 40 or more kHz was very costly, now you just go and buy a $200 sound card, a $400 loudspeaker, and you're there.
Title: High Playback Sampling Frequencies
Post by: icstm on 2012-02-17 23:27:26
10 or 20 years ago getting  equipment capable of producing sounds up to 40 or more kHz was very costly, now you just go and buy a $200 sound card, a $400 loudspeaker, and you're there.
but is the 50-90khz range necessary or even achievable through speakers by the sampling afforded at 192k?
most roll off well before there (so the 24bit depth is even less useful...)
Title: High Playback Sampling Frequencies
Post by: Bartholomew MacGruber on 2012-02-19 14:14:13
I'm still confused as to why studios use really high sampling frequencies.  I have a vague understanding of why higher bit depths might be needed for adujsting levels, but I don't get why they need higher sampling rates.
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-19 22:12:49
I'm still confused as to why studios use really high sampling frequencies.  I have a vague understanding of why higher bit depths might be needed for adujsting levels, but I don't get why they need higher sampling rates.


bigger number == better
Title: High Playback Sampling Frequencies
Post by: Walter_Odington on 2012-02-19 23:52:34
For producing sound/music then higher bit depths and sample rates can have advantages (and disadvantages).

- time stretch and other granular based pitch/time changes allow smaller grain size, and relatively smoother grain size resolution. A clearly audible difference can be heard here.

- signal processing at higher depth/resolution can preserve signals above above audible frequencies that will affect the sound at audible frequencies i.e. control signals may have less audible artefacts at hight depth/resolution. Simular to above.

- resampling to change pitch is a common process. Resampling at higher resolution will remain more faithful to the original, and sounds outside of the audible range may be transposed down whereas if sampled at 44.1 you may end up with dull sounds when pitched down (although, who knows what is up there!).

- Presumably higher bit depth give you more range to play with when recording. Someone may correct me on that one.

- Higher depth/resolution hardware tends to be more inaccurate, jitter etc.

- Processing overhead and disk space usage could be quite insane.
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 00:08:13
For producing sound/music then higher bit depths and sample rates can have advantages (and disadvantages).

- time stretch and other granular based pitch/time changes allow smaller grain size, and relatively smoother grain size resolution. A clearly audible difference can be heard here.

- signal processing at higher depth/resolution can preserve signals above above audible frequencies that will affect the sound at audible frequencies i.e. control signals may have less audible artefacts at hight depth/resolution. Simular to above.

- resampling to change pitch is a common process. Resampling at higher resolution will remain more faithful to the original, and sounds outside of the audible range may be transposed down whereas if sampled at 44.1 you may end up with dull sounds when pitched down (although, who knows what is up there!).


I don't think any of this is true with respect to sampling rate, since any effect processing could trivially upsample if it actually needed to prior to processing.  Like I said before, I think the ral reason that higher sampling rates are used is that they exist and there is no real down side to using them so people use them.  People really do like bigger numbers. 
Title: High Playback Sampling Frequencies
Post by: Walter_Odington on 2012-02-20 00:33:48
I don't think any of this is true with respect to sampling rate, since any effect processing could trivially upsample if it actually needed to prior to processing.  Like I said before, I think the ral reason that higher sampling rates are used is that they exist and there is no real down side to using them so people use them.  People really do like bigger numbers.


Depends on the software. For example, ableton live time stretch is based on the DAW setting, Reaktor has its own processing settings, and UAD has 192 sample rate as standard.

Im not saying higher is better for all situations, but these are some which do benefit from higher numbers. On the flip side, I could imagine a situation where a CD would have been better off coming from a 44.1 native project than a 96 kHz project due to quantisation error, so I don't think higher is better in ever situation. For me, it makes sense to work in as high a resolution as possible even if the delivery file is a 3gp, because the processing has a clearly audible difference. Plus I get drawn in to marketing speil :-p
Title: High Playback Sampling Frequencies
Post by: greynol on 2012-02-20 00:48:56
the processing has a clearly audible difference.

Before posting again, please review the terms (http://www.hydrogenaudio.org/forums/index.php?showtopic=3974) you accepted when registering, paying special attention to #8, the one you have violated twice in this discussion.
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 01:06:24
I don't think any of this is true with respect to sampling rate, since any effect processing could trivially upsample if it actually needed to prior to processing.  Like I said before, I think the ral reason that higher sampling rates are used is that they exist and there is no real down side to using them so people use them.  People really do like bigger numbers.


Depends on the software. For example, ableton live time stretch is based on the DAW setting, Reaktor has its own processing settings, and UAD has 192 sample rate as standard.


You're just pointing out what I said:  that people like higher numbers.  But that says nothing about the importance of those numbers. 

Im not saying higher is better for all situations, but these are some which do benefit from higher numbers.


Would it trouble you to mention them?

On the flip side, I could imagine a situation where a CD would have been better off coming from a 44.1 native project than a 96 kHz project due to quantisation error,


Quantization error has absolutely nothing to do with sampling rate.  Perhaps you should look up what quantization error is prior to expressing your opinions on it . . .
Title: High Playback Sampling Frequencies
Post by: Walter_Odington on 2012-02-20 01:34:51
I see I have walked in to the lions den!

I'll prepare an ABX test of ableton live at different sample rates.



I understand this is a forum for scientists, but I didn't realise scientists could be so tetchy! I'm not trying to get one over anyone, just puttin some perspective accross that might be relevant. I won't repeat or elaborate on my original points until I have some evidence, but I would like to respond that quantisation does have something to with sample rates when you change them.

I'm not a complete dunce Saratoga, sorry if ive offended the sensibilities of the forum, but you come across really petty in your post above. I will take the criticism on board and try and improve my conduct going forwards!
Title: High Playback Sampling Frequencies
Post by: greynol on 2012-02-20 01:49:47
I won't repeat or elaborate on my original points until I have some evidence, but I would like to respond that quantisation does have something to with sample rates when you change them.

Would you like to provide some explanation rather than just say that it does in order to help those who don't have the same level of understanding as you?
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 01:52:31
I understand this is a forum for scientists, but I didn't realise scientists could be so tetchy! I'm not trying to get one over anyone, just puttin some perspective accross that might be relevant.


I don't agree with that.  When you come in assert something to be true that you do not know to be true, you are in fact trying to "get one over" on everyone.  People will indeed get "tetchy" when you give them reason to suspect you. 

I'll prepare an ABX test of ableton live at different sample rates.


You should start a new thread and discuss the setup for this experiment before committing a lot of time to it.  It sounds like you may not be aware of some of the previous experience people have with ABX testing sample rates. 

I would like to respond that quantisation does have something to with sample rates when you change them.


It does not.  You may be thinking of rounding error, or possibly something else.  Its unclear from your post exactly what you were trying to say.
Title: High Playback Sampling Frequencies
Post by: Walter_Odington on 2012-02-20 01:56:20
I think I've misunderestimated the amount of effort that should go in to a post on here. I'll pipe down until Ive got something to say with discernable provanence.

Ps, reread my previous post, sorry if I come across as an arse saratoga - bit of a rash comment from me, I just felt like I was being hung out to dry when it wasn't warranted. Think I 'get' this forum that little bit more now, and the rigours required from participants. (although how did the guy who said each channel has half the samples get off Scott free?!? ;-)
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 02:09:52
Ps, reread my previous post, sorry if I come across as an arse saratoga - bit of a rash comment from me, I just felt like I was being hung out to dry when it wasn't warranted. Think I 'get' this forum that little bit more now, and the rigours required from participants. (although how did the guy who said each channel has half the samples get off Scott free?!? ;-)


No problem, and I didn't mean to discourage you from posting in the future. Sorry if I came off like that.
Title: High Playback Sampling Frequencies
Post by: Walter_Odington on 2012-02-20 02:09:55
Saratoga, just seen your latest. I appreciate I need to explain myself, but I don't believe I've actually said anything incorrect. Your arguments don't leave much room for any truth that may reside in my blabbering, yet there is something in what I'm saying.

What I've said previously re sample rates/depths has been too vague, which is evidently a cardinal sin round here, I will seek to improve that, but is it really right to rubbish my points because they are poorly expressed?


Edit - you've probably encouraged me to post better than not post, just felt like a bit of a sledge hammer!
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 02:22:04
Saratoga, just seen your latest. I appreciate I need to explain myself, but I don't believe I've actually said anything incorrect. Your arguments don't leave much room for any truth that may reside in my blabbering, yet there is something in what I'm saying.


Qunatization error is the error when quantizating a signal to a finite number of bits.  For instance, 17 bit sample have half the quantization error of 16 bit samples.  Sampling rate is the frequency at which samples are recorded.  They are mathematically related in a very complex way, but for our purposes they have nothing to do with each other since the error per sample doesn't change if you record one sample per second and then upsample it to 2 Hz or 2khz or 2Mhz.  Each sample would still have an error of approximately 2^-(N+1) for an N bit quantization. 

With that in mind,

On the flip side, I could imagine a situation where a CD would have been better off coming from a 44.1 native project than a 96 kHz project due to quantisation error,


the problem with this statement is that it implies that changing sampling rate has something to do with quantization error, when (at least in this context) it doesn't. 

What I've said previously re sample rates/depths has been too vague, which is evidently a cardinal sin round here, I will seek to improve that, but is it really right to rubbish my points because they are poorly expressed?


No I'm rubbishing them because I don't think you fully understand the question, and to illustrate that I'm pointing out that you're not using the terminology consistently with the depth of understanding required to give a useful opinion.
Title: High Playback Sampling Frequencies
Post by: Ron Jones on 2012-02-20 02:37:04
Presumably higher bit depth give you more range to play with when recording. Someone may correct me on that one.

I'm not sure what you mean by "range". Are you referring to frequency response?

Higher depth/resolution hardware tends to be more inaccurate, jitter etc.

Not to my knowledge. It's possible, certainly, that this statement is true in some cases. I don't believe there's a tendency for this to be the case. In many cases the same components responsible for clocking and converting 'high-res' audio are the same as the hardware you'll find in more limited devices: the latter devices often just don't expose the capabilities of the underlying hardware, for one reason or another.

Processing overhead and disk space usage could be quite insane.

The increase in computational effort is generally negligible. As for disk usage, I suppose you could argue that, but you can also argue that the storage demands of 'high-res' audio is small potatoes compared to even compressed video or uncompressed imagery.
Title: High Playback Sampling Frequencies
Post by: IgorC on 2012-02-20 02:50:09
They are mathematically related in a very complex way

That will be: 4x oversampling leads to additional +1 bit of bit depth, right?
Title: High Playback Sampling Frequencies
Post by: Walter_Odington on 2012-02-20 03:53:50
Your right that my understanding is limited given the company I'm in, and I totally accept that, but am i the only person here who thinks quantisation error is rounding error? I'll endeavour to be useful and use correct terminology.

What I meant originally was that by converting to a new sample rate, some of the new samples will be have a position in time in between old samples, and as such require some computational decision to be made on their value (interpolation or rounding or prediction or whatever system is in place). Whatever the process involved, the new values will have a lesser accuracy and the signal will have been degraded. And so keeping a constant sample rate may be better in some instances, be because a step of processing (and resultant degradation) can be avoided. Counter to that, I believe there are processes from which working at a higher sample rate does improve the sound:

Ill try to elaborate on the suggestion that granular time stretching can benefit from a higher sample rate. When time stretching, the sound is split up in to little grains of the ms magnitude. The larger the grain, the more noticeable the granulation when the tempo is lowered - this is because of the grains starting from a very similar point with reference to the source sound relative to total grain duration ie the onset of a new grain results in going back in time above a critically significant quantity (some may cite haas effect for thresholds of perception on sound events). The result is a weird "gl-gl-gl-gl" sound you can hear on a lot of 90s dance tracks, Ripgroove by Double99 ft Top Cat being a prime example where the man says "Brock out". To counter this undesirable sound processing artefact the grain size needs to be reduced so that each grain onset is less perceptible. At a higher resolution you can get smaller grain sizes, get less perception of the granulation, and some may say a better sound. I'll return with some audio to illustrate this.

Similarly, when sampling a sound and then playing it back at a different pitch there is benefit to processing at a higher sample rate. Samplers re-pitch sound, and this is almost always done by resampling. If the sample contains audio up until half the sample frequency then it follows that a 48kHz sample played back at the original pitch has an upper limit of 24khz. If this is played back two octaves lower then the upper limit of the sound spectrum is 6khz. If we had a sample of 192khz then it would have an upper limit of 96khz, and played back two octaves below would still have frequency content wih an upper limit of 28khz. The sound sampled at 48khz will sound dull when pitched down, the sound at 192 will maintain more sense of the original full frequency sound. I'll return with examples to illustrate this too.

Edit: tried to make it clearer
Title: High Playback Sampling Frequencies
Post by: wakibaki on 2012-02-20 04:14:21
Just as an aside, bit depths and sampling rates are interchangeable, you can trade one for the other, with the proviso that the Nyquist limit still holds. A simple on-off signal can encode any analogue signal to an arbitrary degree of accuracy as pulses of equal magnitude and duration if the duration of the pulses is reduced sufficiently. Suppose a 44k1/16 signal were to be recoded into a bitwide stream. If in every sample period (1/44100 sec) between 0 and 65535 bits (ones) (depending on the numeric value of the sampled signal) could be transmitted then the signal would be effectively recoded. For reconstruction purposes the numeric values could be recovered at a rate of 44k1 by a counter if by no other expedient.

The increasing popularity of high playback sampling rates could be attributed to a not entirely irrational desire for margin (overkill).

Amplifiers with very low THD are desired by some (me even). In a circumstance where the limits of perception are difficult to establish, for one reason or another, a simple strategy for ensuring the inaudiblity of error is to exceed the probable limits by a margin, even a large margin.

w
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 04:59:37
They are mathematically related in a very complex way

That will be: 4x oversampling leads to additional +1 bit of bit depth, right?


2x.  When you oversample by 2x you have the same error per sample, but 2x the bandwidth.  So the error per bandwidth is 1/2 as much meaning one more bit.  At least thats the case assuming the error is randomly distributed which may or may not be true.

What I meant originally was that by converting to a new sample rate, some of the new samples will be have a position in time in between old samples, and as such require some computational decision to be made on their value (interpolation or rounding or prediction or whatever system is in place). Whatever the process involved, the new values will have a lesser accuracy and the signal will have been degraded.


The process is called interpolation, and no, thats not generally a problem.  Interpolation can be done with essentially unlimited accuracy, such that it is widely regarded (assuming proper implementation of course) as having no impact on quality.  Do a search, this has been discussed to death and in far more detail then I have time for.

Ill try to elaborate on the suggestion that granular time stretching can benefit from a higher sample rate. When time stretching, the sound is split up in to little grains of the ms magnitude. The larger the grain, the more noticeable the granulation when the tempo is lowered


Since any time stretch algorithm can set the sampling rate as high as it likes for processing purposes, it doesn't really matter what the input sampling rate is.

Similarly, when sampling a sound and then playing it back at a different pitch there is benefit to processing at a higher sample rate. Samplers re-pitch sound, and this is almost always done by resampling. If the sample contains audio up until half the sample frequency then it follows that a 48kHz sample played back at the original pitch has an upper limit of 24khz. If this is played back two octaves lower then the upper limit of the sound spectrum is 6khz.


Well yes, for recording ultrasounic information, higher sampling rates are quite obviously useful.  But we're talking about music.  Not, bat calls.  Music is generally assumed to occupy the range of frequencies humans can here, and for those 48k is quite sufficient.  If you wish to record things that humans cannot hear, then by all means go buy a 1MHz A/D. 
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 05:09:30
The increasing popularity of high playback sampling rates could be attributed to a not entirely irrational desire for margin (overkill).

Amplifiers with very low THD are desired by some (me even). In a circumstance where the limits of perception are difficult to establish, for one reason or another, a simple strategy for ensuring the inaudiblity of error is to exceed the probable limits by a margin, even a large margin.


I don't really agree with this analogy.  Lower THD on a amplifier means higher accuracy and more headroom when driving more difficult loads.  Its generally useful and a reasonable metric of 'goodness'.

Higher sampling rates are not generally useful, nor are they an acceptable measure of how good something is.  I cannot look at a ADC, see that it supports 96k and know that it has generally good performance.  Plenty of very bad ADC devices support 96k.  If I want to know how good an ADC is, one of the last things I would ever ask is the range of needlessly high sampling rates it supports.  In contrast, I can look at an amp, see that it has 0.01% THD into a 4 ohm load and be more then reasonably sure it'll perform well for another 4 ohm load. 
Title: High Playback Sampling Frequencies
Post by: knutinh on 2012-02-20 07:34:47
The increasing popularity of high playback sampling rates could be attributed to a not entirely irrational desire for margin (overkill).

Amplifiers with very low THD are desired by some (me even). In a circumstance where the limits of perception are difficult to establish, for one reason or another, a simple strategy for ensuring the inaudiblity of error is to exceed the probable limits by a margin, even a large margin.


I don't really agree with this analogy.  Lower THD on a amplifier means higher accuracy and more headroom when driving more difficult loads.  Its generally useful and a reasonable metric of 'goodness'.

Higher sampling rates are not generally useful, nor are they an acceptable measure of how good something is. 
...

I think talking about "exceeding probable merits with a large margin" has some validity when talking about possible artifacts from lowpass-filtering found in any ADC/DAC. If the sampling rate is 10kHz, this filter will be heard by most people. If the sampling rate is increased to 32 kHz, a well-designed filter will probably not be heard. Going to 44.1kHz, 48kHz, 88.2kHz etc could be seen as "safeguards" if one can expect everything else to be equal, especially since this move has close to zero cost for many applications. It may well be an excessive, redundant safeguard that can be easily reduced by attending a lower-level course in digital signal processing and/or human hearing 101, but still be a safeguard.

Any assertion that this _does_ affect sound, significantly, across many systems, would make by BS-detector go "beep".

-k
Title: High Playback Sampling Frequencies
Post by: icstm on 2012-02-20 10:32:13
As I wrote the OP, I am going to wade in here 

Those of you talking about time stretching and other effects are (in my mind) essentially creating music, rather than playing it.
Those of you talking about safeguards I think this only applies to the digitisation process (ie capturing in the ADC at higher sampling rates)

Once all adjustments are complete, why not encode in 44.1 / 16?


Talking about THD, gives an example of the relevant attributes to check in anologue components.

Just to check another stupid question (ok the first one wasn't stupid, but I wanted to make sure no one could convince me otherwise).

Are we sure that humans have no reaction to near ultrasonic frequencies?
Title: High Playback Sampling Frequencies
Post by: zaentzpantz on 2012-02-20 11:02:30
OK, at the risk of sounding completely stupid?

Why do people listen to music with high sampling frequencies?
What is 88k+ providing them?
I understand why you might record at a high sampling rate, but why keep that for playback?

Looking through the FAQ, there are threads from 2003 that point out that the sampling frequency and bit-dept work in tandem. So the quantisation error of 16bit at 44.1k has the opportunity to be corrected sooner at a higher sampling rate, so in some ways is like a dithering pattern.

However given noise introduced in the analogue systems required to listen to music, a SNR within a 16bit signal  of ~96dB seems pretty good.

So assuming that speakers struggle to produce the sounds that a 192k sampling frequency allow (eg 96kHz) and assuming that 16bits were sufficient when compared to the analogue equipment in the system, what have I missed in these high sampling playback formats?


The main benefit of a higher sampling rate is that the anti-aliasing filtering can have a flatter roll-off. There is a school of thought that the harsh sound of cds is due to the brickwall filter at around 20kHz and the effects of it's phase/time aberrations. With 96kHz, the filter only needs to cut off by 48kHz so a gentle slope from 20kHz-48kHz is used with much less phase/time aberrations.
Another is the as yet unexplained effect of supersonic frequencies on the sound, discovered by engineers at George Martins' Air studios in the 70s. One channel module always sounded better than the others in the recording console, and after research by the designer (Rupert Neve) the only difference found was an omitted termination resisitor which allowed the frequency response to extend up to around 90kHz. When fitted it then sounded the same as the other modules and the frequency response was reduced to around 40kHz. Nobody has found out why this could be heard, but the people involved were sufficiently respected to be believed and has given birth to the odd practise of extending audio response beyond our hearing limits.
Title: High Playback Sampling Frequencies
Post by: 2Bdecided on 2012-02-20 11:21:52
People are selling music in high sample rates and bitdepths because enough people believe it sounds better to make it marketable (at least in a niche market!). Whether it actually sounds better or not is kind of irrelevant.

Where multiple versions are released, it can also be the place where a less compressed master is used, and/or more information/artwork/etc are included etc - or sometimes not. It's a nice excuse to charge more for these features. Just like Sony used to use better masters for making gold CDs in the 1990s. They'd sound just as good on a normal CD, but there'd be less excuse to charge extra.


The audio industry, which released a format good enough for all possible two channel music recordings in 1983 and managed to sell all the music from the past 100 years all over again in that format, is now looking on in envy at the film industry which has managed to pull the trick three times: VHS, DVD, and now BluRay. The crippled audio industry is desperate to pull the same trick again.


In recording studios, a lot of it is Emperor's New Clothes - and a lot of it is "why not?". There's no meaningful cost differential to working at 24/96 than 20/48. No one in a real studio worked at 16/44.1 during the last 20 years anyway.

Cheers,
David.
Title: High Playback Sampling Frequencies
Post by: Arnold B. Krueger on 2012-02-20 13:06:08
The main benefit of a higher sampling rate is that the anti-aliasing filtering can have a flatter roll-off. There is a school of thought that the harsh sound of cds is due to the brickwall filter at around 20kHz and the effects of it's phase/time aberrations.


AFAIK that so-called school of thought was actually a school of non-thought and non-observation. It has been conclusively shown repeatedly that the alleged harsh sound of PCs were unrelated to the reb book CD's technical parameters or even the portions of the implementation of it that were unique to the CD.

The biggest problem with the CD was that it was such a big technical improvement that it generally made things sound different by actually removing a bunch of technological veils that just about everybody with a serious interest in audio technology knew full well about.

From a practical viewpoint, the introduction of the CD was the most successful advance in media technology until the introduction of the DVD.
Title: High Playback Sampling Frequencies
Post by: icstm on 2012-02-20 13:43:28
The main benefit of a higher sampling rate is that the anti-aliasing filtering can have a flatter roll-off. There is a school of thought that the harsh sound of cds is due to the brickwall filter at around 20kHz and the effects of it's phase/time aberrations. With 96kHz, the filter only needs to cut off by 48kHz so a gentle slope from 20kHz-48kHz is used with much less phase/time aberrations.

So use higher sampling frequencies in the capturing and the digitisation of the music, then store for playback at 44.1? surely? 
Another is the as yet unexplained effect of supersonic frequencies on the sound, discovered by engineers at George Martins' Air studios in the 70s. One channel module always sounded better than the others in the recording console, and after research by the designer (Rupert Neve) the only difference found was an omitted termination resisitor which allowed the frequency response to extend up to around 90kHz. When fitted it then sounded the same as the other modules and the frequency response was reduced to around 40kHz. Nobody has found out why this could be heard, but the people involved were sufficiently respected to be believed and has given birth to the odd practise of extending audio response beyond our hearing limits.
this is interesting, I like to see if this has been copied elsewhere.
Title: High Playback Sampling Frequencies
Post by: knutinh on 2012-02-20 14:17:02
...in envy at the film industry which has managed to pull the trick three times: VHS, DVD, and now BluRay. The crippled audio industry is desperate to pull the same trick again.

Perhaps four times: Bluray 3D.

If physical formats is deemed a viable source of income, may I suggest to the audio industry that they release something within the Bluray standard that:
1. Contains new content and/or higher mastering standards (as in "sounds better", not "our numbers are larger than yours")
2. Is multichannel or binaural
3. Prioritize customer experience over DRM paranoia

I do believe that many (like me) are willing to pay more than 1$ a song if the product is perceived as good enough. A lot of this can be done within the CD-format, but multichannel may be hard.

-k
Title: High Playback Sampling Frequencies
Post by: WernerO on 2012-02-20 14:22:08
There is a school of thought that the harsh sound of cds is due to the brickwall filter at around 20kHz and the effects of it's phase/time aberrations. With 96kHz, the filter only needs to cut off by 48kHz so a gentle slope from 20kHz-48kHz is used with much less phase/time aberrations.


1) The vast majority of ADC and DAC chips employ linear phase FIR filters for anti-aliasing and anti-imaging. So there are no phase/time aberrations.

2) While one could use a shallow slope rolling off between 20kHz and 40kHz with 2x sample rate, this is not what the vast majority of ADCs or DACs do. They cut off just as steeply (well, almost) as in the 1x sample case.


So use higher sampling frequencies in the capturing and the digitisation of the music, then store for playback at 44.1? surely?


Prior to 'storing for playback at 44.1kHz' one has to downsample, which implies and includes steep anti-alias filtering at 22.05kHz. Sort of back to square 1, not?

Title: High Playback Sampling Frequencies
Post by: greynol on 2012-02-20 16:05:40
Have we conveniently forgotten that CD players commonly employed over sampling in order to aid in reconstruction?

Title: High Playback Sampling Frequencies
Post by: icstm on 2012-02-20 16:19:00
Have we conveniently forgotten that CD players commonly employed over sampling in order to aid in reconstruction?

In the DAC? That is fine, they are not trying to create information that is not there they are doing signal processing. I am no expert, but I think I am comfortable with a DAC using oversampling and for the rest of the consensus of the argument posted through the thread to remain.

Prior to 'storing for playback at 44.1kHz' one has to downsample, which implies and includes steep anti-alias filtering at 22.05kHz. Sort of back to square 1, not?
Why would I have to do that. The signal has already been sampled. I already have the information in a desired format. The issue is that I have "too much" information. So I need to drop some of it. An anti-alias filter would be used if I was ambiguous about the information I have, but (assuming I used one before whilst working with the higher sampling rates) I am not. I know what frequencies I have.

In fact, before I sample to 44.1, I could process my signal at the higher sampling rate to not include frequencies above 22k. Remember that this is not an anologue information, where I might worry about a low-pass filter, this is in the digital domain.

Does that make sense?
Title: High Playback Sampling Frequencies
Post by: xnor on 2012-02-20 16:30:04
In fact, before I sample to 44.1, I could process my signal at the higher sampling rate to not include frequencies above 22k.

Which is called a low pass filter that acts as an anti-aliasing filter.
Title: High Playback Sampling Frequencies
Post by: greynol on 2012-02-20 16:33:55
Right, I see that we were talking about removal of greater than Nyquist in the digital domain prior to reconstruction.  Still lots of concern about anti-aliasing/anti-imaging, but not a lot of objective data demonstrating that it's been a problem over the last decade if not longer?
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 16:35:49

Have we conveniently forgotten that CD players commonly employed over sampling in order to aid in reconstruction?

In the DAC?

Yes.  Modern DACs are oversampled.  It gives you better bit depth and less risk of aliasing essentially for free. 

In fact, before I sample to 44.1, I could process my signal at the higher sampling rate to not include frequencies above 22k. Remember that this is not an anologue information, where I might worry about a low-pass filter, this is in the digital domain.

... which is what a modern oversampling ADC  does.  I suspect you think that a 44.1khz ADC/DAC actually runs at 44.1khz.  This is not the case and has not been for perhaps 2 decades with the advent of practical CMOS transistors.  Common 384x oversampling implies frequencies in the MHz where digitally applying the anti-alias filter is simple. 

So yes, what you're saying is a sound idea.  So sound its already integrated into every ADC/DAC you've ever used

Edit:  wrote DAC when I meant ADC
Title: High Playback Sampling Frequencies
Post by: Arnold B. Krueger on 2012-02-20 17:19:13
Have we conveniently forgotten that CD players commonly employed over sampling in order to aid in reconstruction?


Let's compare and contrast oversampling which is what just about all modern digital<->analog converters do, with upsampling or simply sampling the same analog signal at a far higher rate.

An oversampled converter can be thought of as a black box that is an interface between digital data at a certain data rate, and analog data that for all the world seems to have been sampled at that same sample rate.  If we apply the rules of ducks to these gizmos in a standard red book CD player, they walk like they run at 44.1 KHz, they quack like they run at 44.1 KHz, and they look like they run at 44.1 KHz. For all practical purposes they are[/b} 44.1 KHz converters. To a certain degree, what happens inside of them is none of our concern.

Upsampling is a completely different thing. If we think of this process as  a black box, it is an interface between stuff that for all the world seems to have been sampled at one sample rate and is now seems to be at some other sample rate. Only by analyzing the data at some deeper level of detail do we get the harsh surprise that first impressions are wrong, and the data actually has properties that are the same or a little worse than it had at the lower sample rate.

Sampling at a higher data rate is again a completely different thing. If we think of this process as a black box, it is an interface between stuff that for all the world seems to have been sampled at a sample rate and is now seems to be like data taken at the same sample rate.  However there are no harsh surprises in terms of data. The data really has the properties of data taken at the sample rate that is right there before us.

However, when we are talking about audio signals that are presented with 44.1 KHz sampling and 16 bit resolution, there may still be some harsh surprises. It turns out that due to some inherent limitations of our ears, the data is generally indistinguishable from data taken at even a lower sample rate (ca. 16 Khz), and with less resolution (ca. 13-14 bits).

Hey I didn't make this world, I just try to make reliable observations of it! ;-)
Title: High Playback Sampling Frequencies
Post by: IgorC on 2012-02-20 17:20:15
...in envy at the film industry which has managed to pull the trick three times: VHS, DVD, and now BluRay. The crippled audio industry is desperate to pull the same trick again.

Perhaps four times: Bluray 3D.

Even more. Blu-Ray/Blu-Ray-3D have very good sales and video industry already thinks of new technology (Ultra High Definition Television, 16x resolution of Blu-Ray).
While the audio industry tries to push better-than-CD DVD-A/SACD without much success.

The prices  of blu-ray players (starting from only 100$) and HD displays are falling very fast.
While some audiophile audio hardware has the same price as from the first day of introduction 10 years ago.  My guess is that the manufacturers of audiophile class hardware keep the prices high because it's impossible to decrease the costs as only very small percentage of people who is interested to buy such hardware.
Title: High Playback Sampling Frequencies
Post by: Ethan Winer on 2012-02-20 19:01:46
I'm still confused as to why studios use really high sampling frequencies.  I have a vague understanding of why higher bit depths might be needed for adujsting levels, but I don't get why they need higher sampling rates.


Because even professional recording engineers can be subject to the same magical thinking and lack of scientific rigor we commonly see among audiophiles. It's just as easy to start a religious war about this stuff in a recording forum as it is in a hi-fi forum.

--Ethan
Title: High Playback Sampling Frequencies
Post by: Ron Jones on 2012-02-20 19:46:35
Because even professional recording engineers can be subject to the same magical thinking and lack of scientific rigor we commonly see among audiophiles.

Define "magical thinking".
Title: High Playback Sampling Frequencies
Post by: knutinh on 2012-02-20 20:24:18
Define "magical thinking".

1. "Some guy that I admire use a magical stone in his room for better sound"
2. "If I do the same, I will have equally good results"
(3. Some company approach the person in 1. and are allowed to use his name in marketing, or pay him something direct/indirect to have their magic stone prominently featured in an interview with some magazine)

We are all susceptible to being "fooled" by the wonderfully complex thing between our ears. Audiophiles, recording engineers and regular engineers.

-k
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-20 21:23:09
I'm still confused as to why studios use really high sampling frequencies.  I have a vague understanding of why higher bit depths might be needed for adujsting levels, but I don't get why they need higher sampling rates.


Because even professional recording engineers can be subject to the same magical thinking and lack of scientific rigor we commonly see among audiophiles.


Yes this has been my experience as well.  The skills required of a good recording engineer are quite different then that of a good DSP/software developer.  Their skills have a little overlap, but are still quite distinct.
Title: High Playback Sampling Frequencies
Post by: Arnold B. Krueger on 2012-02-21 12:43:43
Because even professional recording engineers can be subject to the same magical thinking and lack of scientific rigor we commonly see among audiophiles.

Define "magical thinking".


Magical Thinking defined in Wikipedia, and that definition looks pretty good to me. Ethan partially defined it in his statement - it involves a lack of scientific rigor. The underlying logical error is usually confusing correlation with causality.

In recording, there are many cases where an engineer will put some highly touted new component into his recording chain and the next recording he makes sounds unusually good to him. The perceived improvement is in his view obviously due to the new component.

On balance, IME actual working recording engineers tend to be far more pragmatic than audiophiles, but there are a lot of poorly-trained dilettantes who make a few pretty good recordings and then try to pass themselves off as world-class experts.
Title: High Playback Sampling Frequencies
Post by: Arnold B. Krueger on 2012-02-21 12:51:59
The increasing popularity of high playback sampling rates could be attributed to a not entirely irrational desire for margin (overkill).


Good point.

Using higher sampling rates is virtually a no-cost option today. AFAIK every decent converter that is designed for use in audio production work has sample rate options up to 24/192. The extra storage and processing required by the need to handle integer multiples more data are now readily available. This even extends to highly portable equipment.

The same can be said of the use of longer data words.

Neither of them are generally effective at actually producing better sound quality, but as the thinking goes - since: "They cost me nothing and give me the perception of reduced risk..."
Title: High Playback Sampling Frequencies
Post by: Woodinville on 2012-02-21 17:12:10
I'm still confused as to why studios use really high sampling frequencies.  I have a vague understanding of why higher bit depths might be needed for adujsting levels, but I don't get why they need higher sampling rates.


Because even professional recording engineers can be subject to the same magical thinking and lack of scientific rigor we commonly see among audiophiles. It's just as easy to start a religious war about this stuff in a recording forum as it is in a hi-fi forum.

--Ethan


Actually, there are occasionally (note the qualification) reasons to be working at a higher sampling rate. If you must do nonlinear processing for some reason, a higher sampling rate helps ensure that aliasing of harmonics does not happen.  This kind of processing is, unfortunately, sometimes necessary. While it is possible to increase the sampling rate for that plugin, how many times do you want to run your signal through the 20kHz antialiasing filters?  Perhaps better to run it once at the end?  Of course, a plugin that accepts lower sampling rate should do upsampling if it must, etc.

Completely dismissing the idea is not appropriate. Just mostly dismissing it is reasonable.

Having said that, indeed, there is a lot of magical thinking in some of the production folks.
Title: High Playback Sampling Frequencies
Post by: Woodinville on 2012-02-21 17:14:16
Good point.

Using higher sampling rates is virtually a no-cost option today. AFAIK every decent converter that is designed for use in audio production work has sample rate options up to 24/192. The extra storage and processing required by the need to handle integer multiples more data are now readily available. This even extends to highly portable equipment.

The same can be said of the use of longer data words.

Neither of them are generally effective at actually producing better sound quality, but as the thinking goes - since: "They cost me nothing and give me the perception of reduced risk..."


Actually, using longer words for capture can create better sound quality, by allowing a "documentation recording" at a known gain, rather than a recording level that is near-peak at its highest.
Title: High Playback Sampling Frequencies
Post by: Ethan Winer on 2012-02-21 18:24:33
Actually, there are occasionally (note the qualification) reasons to be working at a higher sampling rate. If you must do nonlinear processing for some reason, a higher sampling rate helps ensure that aliasing of harmonics does not happen.


Sure, and de-clicking software can work better when LPs are recorded at a higher sample rate, because the click rise-times are faster than the music.

Quote
Just mostly dismissing it is reasonable.
Having said that, indeed, there is a lot of magical thinking in some of the production folks.


Exactly, I see this all the time at the womb and gearslutz.

--Ethan
Title: High Playback Sampling Frequencies
Post by: wakibaki on 2012-02-22 01:57:30
Neither of them are generally effective at actually producing better sound quality, but as the thinking goes - since: "They cost me nothing and give me the perception of reduced risk..."


Precisely.

I look forward to the day when both higher sample rates and greater bit-depths are widely adopted, not because I feel they offer an improvement in SQ, but because I think (admittedly perhaps mistakenly) that they will offer less opportunity for the sowing of FUD in the consumer.

w
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-22 02:54:48
I look forward to the day when both higher sample rates and greater bit-depths are widely adopted, not because I feel they offer an improvement in SQ, but because I think (admittedly perhaps mistakenly) that they will offer less opportunity for the sowing of FUD in the consumer.


Ha, I wish.  The day everyone has 96k/24 bit audio is the day they start selling 192k remasters

No matter how big of a number you have people will eventually find a way to bullshit about a bigger one.
Title: High Playback Sampling Frequencies
Post by: wakibaki on 2012-02-22 03:44:21
No matter how big of a number you have people will eventually find a way to bullshit about a bigger one.


I understand how you feel, but IMO it is only a feeling. The less people act out of their hopelessness the greater the likelihood things will change. Once we get to 192k it'll be really hard to argue the necessity for anything more.

w
Title: High Playback Sampling Frequencies
Post by: knutinh on 2012-02-22 06:59:05
I understand how you feel, but IMO it is only a feeling. The less people act out of their hopelessness the greater the likelihood things will change. Once we get to 192k it'll be really hard to argue the necessity for anything more.

It is hard to argue the necessity of anything more than 44.1k.

This does in no way inhibit glossy audio magazine writers from claiming audible limitations of 44.1 to be a fact, and anyone questioning it to be evil.

192kHz, 384kHz,... they will never stop.

Imagine the consequences if they actually talked about the stuff that matters? Such as mastering practices, loudspeaker/room, multichannel? If they did that and limited the use of meaningless artsy words, I might buy their magazines.

-k
Title: High Playback Sampling Frequencies
Post by: icstm on 2012-02-22 14:13:39
In fact, before I sample to 44.1, I could process my signal at the higher sampling rate to not include frequencies above 22k.

Which is called a low pass filter that acts as an anti-aliasing filter.

My understanding is that an anti-aliasing filter is applied prior to digitisation, to remove the ambiguity that arises from sampling.
What I am suggesting within the digital domain. In the digital (sampled) domain, the probablems that others have pointed to around anologue low pass filters do not apply.

Right, I see that we were talking about removal of greater than Nyquist in the digital domain prior to reconstruction.  Still lots of concern about anti-aliasing/anti-imaging, but not a lot of objective data demonstrating that it's been a problem over the last decade if not longer?
I agree, which was the reason for my OP. I agree that DAC use oversampling (as the post below yours points to) but that does not take away from the fact that 16bits per channel of information sampled at 44.1kHz is a suitable way to store music and is not improved upon by higher formats. Nothing posted here has changed my beleive and some posts have provided some evidence to support this position.
Title: High Playback Sampling Frequencies
Post by: xnor on 2012-02-22 14:41:16
My understanding is that an anti-aliasing filter is applied prior to digitisation, to remove the ambiguity that arises from sampling.
What I am suggesting within the digital domain. In the digital (sampled) domain, the probablems that others have pointed to around anologue low pass filters do not apply.

It's also applied in the process of up- or downsampling to ensure that the sampling theorem is satisfied. Lets say you record at 88.2 kHz, now if you want to throw away every second sample you have to filter the signal with a lowpass first (usually done using a steep linear phase FIR), else the ambiguity you mentioned (aka aliasing) kicks in. Sure, compared to analogue filters there is no phase shift, etc.
Title: High Playback Sampling Frequencies
Post by: wakibaki on 2012-02-22 14:49:35
...the fact that 16bits per channel of information sampled at 44.1kHz is a suitable way to store music and is not improved upon by higher formats.


QED. Despite the enormous hooraw raised in some quarters this can be taken as a fact. No manufacturer or researcher has succeeded in demonstrating the contrary in double blind testing, the most recent authoritative study being that presented in the 2007 issue of the Journal of the Audio Engineering Society (Volume 55, Number 9) by E. Brad Meyer and David R. Moran.  Differences in noise floor become perceptible only when the volume is turned up to unrealistic levels.

w
Title: High Playback Sampling Frequencies
Post by: Ethan Winer on 2012-02-22 17:42:07
No matter how big of a number you have people will eventually find a way to bullshit about a bigger one.

Exactly. Some people prefer to believe in magic. They may even be wired that way. They wanted to believe when watching the X Files years ago, and they want to believe in magic today too. Education is our only hope. I've always thought that school kids should be taught logic and consumerism starting in in the first grade. Seriously.

--Ethan
Title: High Playback Sampling Frequencies
Post by: db1989 on 2012-02-22 17:50:52
I've always thought that school kids should be taught logic
To which I would add ‘the’ scientific method, and skepticism/critical thinking, and the appropriate amount of geography necessary to appreciate the environment and its other inhabitants, and probably many more. English, maths, and French (in my case) are fine, I guess, but this is nowhere near enough.

Quote
and consumerism
This might be where we diverge in opinion! If you mean ‘not buying total crap’, I agree; but I in no way support any teaching of consumerism as a lifestyle, vehicle of progress, bastion of civilisation, or whatever they’ve been trying to portray it as since the first third of the 19th century. What I think we need is to buy less crap, ideally to buy no crap (read: just useful/necessary things), and perhaps to try to think about something to put in place of buying altogether. But I digress!
Title: High Playback Sampling Frequencies
Post by: Woodinville on 2012-02-23 03:56:08
My personal belief (and I make no apologies in presenting it and would be honored to be credited in its fulfillment) is that the audiophile rags and their faith-based minions aren't going to stop pushing for more once they've reached some arbitrary threshold.


I think it goes well beyond the magazines. The manufacturers of equipment like http://www.lessloss.com/firewall-p-196.html (http://www.lessloss.com/firewall-p-196.html) and http://www.bybeetech.com/ourtech.asp (http://www.bybeetech.com/ourtech.asp) are not going to "stop that" regardless.

A couple of interesting quotes from those sites, first Bybeetech:
Quote
During transit through the Quantum Purifier, quantum noise energy is stripped off the electrons, streamlining their flow through ensuing conductors.

and Less Loss:
Quote
In traditional filtering networks, very high frequency noise circumvents capacitors and coils. Without using such traditional filtering elements, the Firewall is a direct enhancement to the unique filtering technology employed in the LessLoss DFPC Signature power cord.


:facepalm:
Title: High Playback Sampling Frequencies
Post by: Walter_Odington on 2012-02-23 05:37:31
What I meant originally was that by converting to a new sample rate, some of the new samples will be have a position in time in between old samples, and as such require some computational decision to be made on their value (interpolation or rounding or prediction or whatever system is in place). Whatever the process involved, the new values will have a lesser accuracy and the signal will have been degraded.


The process is called interpolation, and no, thats not generally a problem.  Interpolation can be done with essentially unlimited accuracy, such that it is widely regarded (assuming proper implementation of course) as having no impact on quality.  Do a search, this has been discussed to death and in far more detail then I have time for.


I'm very surprised to hear that resampling can be achieved with limitless accuracy, however if it's been done to death on here then I can accept that there must truth in what your saying. With the kind of real world examples that I'm talking about, samplers etc, there is not limitless accuracy. I know this is a sweeping statement with no ABX tests, but with that caveat I continue to assert it because there is truth in it. My main concern about sampling is preserving the frequency content when pitching down.

Ill try to elaborate on the suggestion that granular time stretching can benefit from a higher sample rate. When time stretching, the sound is split up in to little grains of the ms magnitude. The larger the grain, the more noticeable the granulation when the tempo is lowered


Since any time stretch algorithm can set the sampling rate as high as it likes for processing purposes, it doesn't really matter what the input sampling rate is.


Yes any algorithm could have good grain size control and up sampling, but I'm talking about the real world context of ableton live and samplers, which do not have these controls, and which do sound significantly different at higher sample rates (I understand ABX or somesuch is required for such sweeping statements - ill endeavour to supply some).

Similarly, when sampling a sound and then playing it back at a different pitch there is benefit to processing at a higher sample rate. Samplers re-pitch sound, and this is almost always done by resampling. If the sample contains audio up until half the sample frequency then it follows that a 48kHz sample played back at the original pitch has an upper limit of 24khz. If this is played back two octaves lower then the upper limit of the sound spectrum is 6khz.


Well yes, for recording ultrasounic information, higher sampling rates are quite obviously useful.  But we're talking about music.  Not, bat calls.  Music is generally assumed to occupy the range of frequencies humans can here, and for those 48k is quite sufficient.  If you wish to record things that humans cannot hear, then by all means go buy a 1MHz A/D.


Glad you agree on this one, it's my main point. Also, writin this on the iPhone I'm not sure I could contend with typing any more! It's a bit fiddly. The arguments you've presented definately give me some food for thought, ill continue to read on.



Sorry original poster, I've taken this off topic. Half the time I'm listening to spotify, so that shows you my stance. Also I'm still buying vinyl, so judging my what I perceive to be the prevailing thoughts on this forum I can be disregarded as a Luddite anyway.
Title: High Playback Sampling Frequencies
Post by: saratoga on 2012-02-23 06:27:40
What I meant originally was that by converting to a new sample rate, some of the new samples will be have a position in time in between old samples, and as such require some computational decision to be made on their value (interpolation or rounding or prediction or whatever system is in place). Whatever the process involved, the new values will have a lesser accuracy and the signal will have been degraded.


The process is called interpolation, and no, thats not generally a problem.  Interpolation can be done with essentially unlimited accuracy, such that it is widely regarded (assuming proper implementation of course) as having no impact on quality.  Do a search, this has been discussed to death and in far more detail then I have time for.


I'm very surprised to hear that resampling can be achieved with limitless accuracy, however if it's been done to death on here then I can accept that there must truth in what your saying. With the kind of real world examples that I'm talking about, samplers etc, there is not limitless accuracy. I know this is a sweeping statement with no ABX tests, but with that caveat I continue to assert it because there is truth in it. My main concern about sampling is preserving the frequency content when pitching down.


If you're getting some loss of quality resampling, then your software is badly broken.  Take a look on this forum.  There are literally more then a dozen pieces of software you can choose from that will give you accuracy far beyond what any DAC can reproduce.  Digital resampling is not a particularly difficult problem.  There is no excuse for using bad software to do it this day in age.
Title: High Playback Sampling Frequencies
Post by: icstm on 2012-02-23 10:00:44
[In response to the above post:] That is what I was (badly) trying to say earlier. I see no problem resampling in the digital domain and thus no problem going from higher sampling rates to 44.1k for final storage and playback.

Sorry original poster, I've taken this off topic. Half the time I'm listening to spotify, so that shows you my stance. Also I'm still buying vinyl, so judging my what I perceive to be the prevailing thoughts on this forum I can be disregarded as a Luddite anyway.
no problem, but i like the fact you use Vinyl AND spotify... 
Title: High Playback Sampling Frequencies
Post by: Ethan Winer on 2012-02-23 18:53:10
I think it goes well beyond the magazines. The manufacturers of equipment like http://www.lessloss.com/firewall-p-196.html (http://www.lessloss.com/firewall-p-196.html) and http://www.bybeetech.com/ourtech.asp (http://www.bybeetech.com/ourtech.asp) are not going to "stop that" regardless.


Yes, but they'd stop making nonsense if people stopped buying it. That's why I mentioned logic, education, and consumerism.

--Ethan
Title: High Playback Sampling Frequencies
Post by: Ethan Winer on 2012-02-23 19:04:04
Define "magical thinking".

knutinh already gave one answer, but this is too important to let pass so quickly. To my mind, magical thinking is behind most of the world's problems. A simple example is a friend of mine, a young woman who truly believes that food tastes better when the chef has love in his heart. Forget that love is a brain function, showing her lack of knowledge about basic physiology. I asked her by what chemical process could "love" affect the taste of food. She had no answer, but continues to believe anyway. This points up another problem with believers: They will not be convinced no matter how compelling the counter arguments. Another person I know barely earns enough to get by, yet spends a fortune on "holistic" products for her two cats.

But magical thinking goes way beyond harmless human foibles like this. If the government spends $10 Million to study whether pornography is harmful, and the study says No, that should be the end of it. Instead, they spend $10 Million more, several times, trying to get the answer they're sure is right. But that still pales compared to all the wars based on "My god is better than your god," which to me is the ultimate example of the harm of magical thinking.

Sorry for the OT rant, but I feel very strongly about this subject.

--Ethan
Title: High Playback Sampling Frequencies
Post by: Walter_Odington on 2012-02-23 20:27:13
Loved food does generally taste better. Now define love
Title: High Playback Sampling Frequencies
Post by: greynol on 2012-02-23 21:17:01
Let's keep this on-topic, please.
Title: High Playback Sampling Frequencies
Post by: rick.hughes on 2012-02-24 13:45:19
Sorry for the OT rant, but I feel very strongly about this subject.

Being among fellow skeptics is one of the reasons I am on HA
Title: High Playback Sampling Frequencies
Post by: Prince Of All Saiyans on 2012-02-24 16:10:02
Magical thinking at its best...

http://www.musicalsounds.us/PDF/AADACI.pdf (http://www.musicalsounds.us/PDF/AADACI.pdf)

Is that even possible?
Title: High Playback Sampling Frequencies
Post by: 2Bdecided on 2012-02-24 17:34:43
Magical thinking at its best...

http://www.musicalsounds.us/PDF/AADACI.pdf (http://www.musicalsounds.us/PDF/AADACI.pdf)

Is that even possible?
That's BS - but more frightening is that people are asking for (and "getting") 32-bit DACs...
http://www.diyaudio.com/forums/digital-sou...-bit-dac-4.html (http://www.diyaudio.com/forums/digital-source/108739-32-bit-dac-4.html)

Cheers,
David.
Title: High Playback Sampling Frequencies
Post by: Ethan Winer on 2012-02-24 17:36:56
^^^ LOL at this in particular:

"a new 66 bit/1536 kHz concept"

Yeah, what a concept. I'm surprised they stopped there. If only they designed their box to use 68 bits at 1592 KHz I'd buy one in a heartbeat.

--Ethan
Title: High Playback Sampling Frequencies
Post by: pdq on 2012-02-24 17:45:08
It's funny, the rest of their specs seem reasonable and achievable, bet where on earth did they come up with 66 bits?
Title: High Playback Sampling Frequencies
Post by: icstm on 2012-03-07 14:21:50
We now have an ANSWER (http://people.xiph.org/~xiphmont/demo/neil-young.html)!!