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Author Topic: 48 kHz vs 44.1 kHz sample rate  (Read 4630 times)

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Offline wforwumbo

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #75 on: October 14, 2020, 01:01:33 PM »
I kept up with page for the first few pages but I could now use a Sample rate for dummies version :laugh:

Here's the core of sampling theory, in layman's terms.

The overall question we want to ask is: if we have information in the analog world and we want to somehow sample the information, how quickly do we need to capture each individual "slice" or "moment" of the analog information, so that when we try to reconstruct the original analog world from our slices/moments we can do so without distortion?

The practical analogy for this that's often given in signal processing classes is taking photos of a tire. If you watch videos of a wheel accelerating, at first it looks like you would expect it to - the wheel is turning, and each successive frame the spokes follow one another in a logical pattern. However, if the wheels start turning too fast, then the spokes complete more than what our brains can process as a "logical turn" and it looks like the spokes are moving backwards. This is because the rate of spinning of the wheel is over half as fast as the frequency in which you are taking pictures. So sampling theorem says: you need to take at least two photos for each fastest turn of the wheel.

Now the topics that are involved in this thread are a follow up to this concept. Once you are over that "two photos per wheel turn" do you get an appreciable difference? Given that it takes up more space to take more photos, and that most people may not hear a significant difference, is it really worth our time/effort/energy to capture the information any faster than twice-per-fastest-wheel-turn?

My arguments in this thread are effectively "if you're just listening to the raw information, it's pretty unlikely. But it's still useful to take more photos per fastest wheel turn, because let's say some video engineer in the future wants to sharpen your photos by individually processing red, green, and blue (an analogy here - please don't get hung up on the details of this precise example) portions of your image. The more photos you have taken, the more accurate each individual color can be processed such that the end transformation and re-addition that a post-production video engineer has done will be cleaner if you've taken more photos, because red/green/blue exist in different frequency bands and interact differently based on their properties."

That's a VERY high-level summary of what I've been trying to get at here for recording at 24/96 (or higher). At the end of the day, for playback you are totally fine listening to and distributing online 16/44.1 data. However, if you have an easily-accessible archive of 24/96 or 24/192, it allows post production people doing remixing work or mastering work a LOT more precision to do their magic, and the end result of the signal processed with filters at 24/192 that is then bounced down to 16/44.1 sounds significantly better (to my ear, at least) than info that was bounced down then processed at 16/44.1.

And this extends to technologies that aren't exactly mainstream - I'll point to the major tech companies investing in spatial audio filtering and processing. So just because you may not appreciate any benefits from higher sample rates doesn't mean you shouldn't still do it.

Does this clarify things for you?
« Last Edit: October 14, 2020, 04:12:29 PM by wforwumbo »
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Offline seethreepo

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #76 on: October 14, 2020, 11:14:46 PM »
 Thanks for dumbing things down a little for me. My comment  was mostly tongue  in cheek. I think I have a decent grasp on things. I was lost when the math equations came up and I don’t think any amount of dumbing down the math will help, as I just don’t have the patience for it.
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Offline kuba e

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #77 on: October 15, 2020, 10:18:02 AM »
It is very nice video. Wforwumbo, I understand. It is good to think of the output analog signal as the original analog signal + frequency bandwidth limitation (due to sampling) + quantization noise (due quantization). And the imagine of ​​stairs may be useful when we are modifying the digital signal in our DAW.

Offline aaronji

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #78 on: October 15, 2020, 11:11:36 AM »
That's a VERY high-level summary of what I've been trying to get at here for recording at 24/96 (or higher). At the end of the day, for playback you are totally fine listening to and distributing online 16/44.1 data. However, if you have an easily-accessible archive of 24/96 or 24/192, it allows post production people doing remixing work or mastering work a LOT more precision to do their magic, and the end result of the signal processed with filters at 24/192 that is then bounced down to 16/44.1 sounds significantly better (to my ear, at least) than info that was bounced down then processed at 16/44.1.

I am not sure whether or not you were being sarcastic, but this cracked me up! I am a taper, a hobbyist. My "post production people" are, well, me. I assume that is true for most of us here; it definitely is for the people I have discussed this with. I think, in general, tapers are pretty minimalist with respect to post-production. Many trim the ends and normalize and that's about it. Others (I am in this group) do some (typically light) EQ'ing, maybe some limiting for stray peaks, some noise removal, and normalization. A few go further, but, even in that group, we are often constrained by the limitations of the type of recording we do.

I would wager that for me (and probably many other tapers) the audible benefits of processing at 24/96 versus 24/28 are pretty marginal. In my case, I doubt it is worth doubling the file sizes. The standard rejoinder: "Storage these days is cheap!" Well, maybe, but I have a couple of drives in my tower and several more in my NAS. I upgrade (and add more) every couple of years and it is not inexpensive in my mind. On top of that, I have a cloud backup option that also costs quite a bit per year and will cost more as I increase the capacity.

I would be curious to hear your comments on rates greater than 96 kHz. Lavry, for example, says that there is a trade-off between speed and accuracy and that the optimal sampling frequency is around 60 kHz, with 88.2 or 96 being the closest typically available rates. [Also perhaps of interest to you is his way of describing the time/frequency relationship using sinc instead of Fourier functions.]
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Offline voltronic

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #79 on: October 15, 2020, 12:38:23 PM »
Some of you may be familiar with this website, which compares the performance of many different software sample-rate converters when converting from 96 kHz to 44.1 kHz.  See the Help section for details of the methodology and why they chose those rates to convert.  Some look nearly flawless; others atrocious.  Could you tell the difference in a blind test?

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Offline wforwumbo

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #80 on: October 16, 2020, 01:38:36 PM »
Thanks for dumbing things down a little for me. My comment  was mostly tongue  in cheek. I think I have a decent grasp on things. I was lost when the math equations came up and I don’t think any amount of dumbing down the math will help, as I just don’t have the patience for it.
Cheers

I'm not sure if it's really dumbing it down, so much as it is trying to explain the philosophical purpose and implications of the theories underlying the tech. If anything, it's trying to synthesize a more general notion of the theory, which I would argue is more challenging than trying to understand the math. If I can't level the concept with everyone eye-to-eye and cannot effectively communicate its theory, I don't fully understand the concept. The math is more of a way of trying to objectify the theory and trying to manipulate it to understand its limitations, not the de-facto ground truth from which the theory happens to stem (a common mistake amongst engineers, and the very plague which drives physics and ironically enough drove me away from studying raw physics in college).

It is very nice video. Wforwumbo, I understand. It is good to think of the output analog signal as the original analog signal + frequency bandwidth limitation (due to sampling) + quantization noise (due quantization). And the imagine of ​​stairs may be useful when we are modifying the digital signal in our DAW.

Sure, cheers. Just remember: it's an analogy for what's happening - not what's actually happening under the hood. Shoving samples around is more art than engineering (and in practice you don't actually shove the samples around, but that's outside the scope of this thread), it's a shame it's so much fun once you get it right because getting it wrong is like pulling your own teeth out.

That's a VERY high-level summary of what I've been trying to get at here for recording at 24/96 (or higher). At the end of the day, for playback you are totally fine listening to and distributing online 16/44.1 data. However, if you have an easily-accessible archive of 24/96 or 24/192, it allows post production people doing remixing work or mastering work a LOT more precision to do their magic, and the end result of the signal processed with filters at 24/192 that is then bounced down to 16/44.1 sounds significantly better (to my ear, at least) than info that was bounced down then processed at 16/44.1.

I am not sure whether or not you were being sarcastic, but this cracked me up! I am a taper, a hobbyist. My "post production people" are, well, me. I assume that is true for most of us here; it definitely is for the people I have discussed this with. I think, in general, tapers are pretty minimalist with respect to post-production. Many trim the ends and normalize and that's about it. Others (I am in this group) do some (typically light) EQ'ing, maybe some limiting for stray peaks, some noise removal, and normalization. A few go further, but, even in that group, we are often constrained by the limitations of the type of recording we do.

I would wager that for me (and probably many other tapers) the audible benefits of processing at 24/96 versus 24/28 are pretty marginal. In my case, I doubt it is worth doubling the file sizes. The standard rejoinder: "Storage these days is cheap!" Well, maybe, but I have a couple of drives in my tower and several more in my NAS. I upgrade (and add more) every couple of years and it is not inexpensive in my mind. On top of that, I have a cloud backup option that also costs quite a bit per year and will cost more as I increase the capacity.

I would be curious to hear your comments on rates greater than 96 kHz. Lavry, for example, says that there is a trade-off between speed and accuracy and that the optimal sampling frequency is around 60 kHz, with 88.2 or 96 being the closest typically available rates. [Also perhaps of interest to you is his way of describing the time/frequency relationship using sinc instead of Fourier functions.]

I came into taping as a studio guy - I have been doing studio production since high school, and the notion of applying my knowledge to my favorite tapers' work is how I got hooked. Eventually I got looped in by the raw sound of tapes and how to perfect that, since the studio adage goes that it's better to spend 20 times getting the right take and applying gentle (at most) filtering sounds infinitely better than spending hours trying to fix a subpar recording. I can say that I've learned LOADS from taping that has made me a much better studio engineer, but I'd like to flip that coin on its head and mention that lots of tapers could learn a thing or two from post production guys to make a better-sounding end product. Even if it's not for "cleaning up a recording," post production requires a careful ear that helps you tune your mic setup to optimize the amount of work you have to do after the fact, and the reason I started (and still continue) doing it is because that final layer of polish can be the difference between "yep this is great music" to "the veil of realism has been drawn, I can sit back and enjoy this recording without the tape getting between me and the music." I would counter-argue that the constraints from limitations of the recording is limited more by taper knowledge and experience toying with post production (followed by frustration of not putting in the time to learn how to equalize and do ear training), rather than a limitation of the medium or method of recording. Just like making a good tape, learning to apply effects in the post chain takes experience and lots of getting it wrong, before you learn how to get it right; and lots of studio guys would stick their noses in the air at how/why we do things, without understanding how it would make their lives way easier.

The difference isn't marginal - it's pretty significant. I really DO need to get sound clips up here, as it'll prove my point better than words. And likewise, it's something I encourage you to try out on your own next time you make a tape, or grab some 24/96 tapes that are uploaded (most of my tapes are up on eTree as 24/96, happy to get you a copy if the torrents are dead). Play with it yourself by doing the filtering at 24/96 and bouncing down to 16/44.1 after processing, versus doing the identical processing at 16/44.1, and see if you really can or can't hear a difference. That does more talking than any amount of typing I can do behind a screen.

I've taped and tracked at 24/192 before, personally it's past the practical limit given wav files can only contain 4 gigs, and given I run 4-6 channels it's just too much bouncing individual tracks/merging them to create sets. 24/96 I can usually squeeze a set of music running 4 channels without needing to splice. The benefits between tracking at 96 and 192 are there to my ear - I've picked them out when double-blinded - but the filter error is low enough to me at 24/96 that I care a little less about the bump up to 192. If there were tech to make my life easier to track and splice/join stereo pairs of tracks at 24/192, I'd do it in a heartbeat and without batting an eye.

I don't think there's a real "optimal" speed/accuracy tradeoff curve for sampling. There are just too many ways to process audio for there to be a magical number for it to boil down to. You can halve your buffer size if you double the sample rate, and have the same effective latency as the same number of samples-per-unit-time are being processed. Seeking an optimal rate is imo a bit of a fallacy - just go as fast as you can accurately and conveniently sample once you are past Nyquist, which is the point of my posting here. If that's 24/48, so be it.

Curious what you mean about using sinc instead of Fourier "functions" - the Fourier transform listed on the last page is a synthesis function that decomposes a signal into a summation of cosine and sine waves that exist within the time signal. The sinc function [a sine divided by the index of the sine, so sinc(x) = sin(x) / x] pops up a whole bunch in filter design engineering with good reason, but I've never seen it used as a domain transform variable.
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Offline aaronji

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #81 on: October 16, 2020, 02:15:51 PM »
I would counter-argue that the constraints from limitations of the recording is limited more by taper knowledge and experience toying with post production (followed by frustration of not putting in the time to learn how to equalize and do ear training), rather than a limitation of the medium or method of recording. Just like making a good tape, learning to apply effects in the post chain takes experience and lots of getting it wrong, before you learn how to get it right; and lots of studio guys would stick their noses in the air at how/why we do things, without understanding how it would make their lives way easier.

Fair enough, but, again, I do this as a hobby. I have a (more than) full-time job, a family, and other hobbies. I make recordings that make me happy and that's pretty much my only goal. I feel like my post-production skills have gotten much better over the years; I could definitely go back and improve on some of my previous efforts, but I also know I will likely never find the time to do that. Maybe when I retire and the boy is in college, by which point my hearing will probably be shot anyway...

Play with it yourself by doing the filtering at 24/96 and bouncing down to 16/44.1 after processing, versus doing the identical processing at 16/44.1, and see if you really can or can't hear a difference.

I don't think anybody is actually doing that, though. I process at the depth/rate with which the recording was made. The conversion to 16/44.1 is basically the last step (except for tracking).

I don't think there's a real "optimal" speed/accuracy tradeoff curve for sampling.

Curious what you mean about using sinc instead of Fourier "functions"

Like I said, those things are from Lavry, an engineer who makes ADCs. The trade-off, as I recall, is due to physical limitations of the analog circuitry. Again from memory, the sinc/Fourier thing had something to do with periodicity in the Fourier that wasn't in his sinc explanation. I am not 100% certain anymore, as I read his papers quite some time ago...
« Last Edit: October 16, 2020, 02:19:00 PM by aaronji »
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Offline Gutbucket

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #82 on: October 16, 2020, 05:29:38 PM »
Some of you may be familiar with this website, which compares the performance of many different software sample-rate converters when converting from 96 kHz to 44.1 kHz.  See the Help section for details of the methodology and why they chose those rates to convert.  Some look nearly flawless; others atrocious.  Could you tell the difference in a blind test?

https://src.infinitewave.ca/

It is Halloween season.  Those scary looking sweep images may appear more frightful than they perhaps should be without an appropriate frame of reference.  Which is not to say there is no reason to use the better performing resampling routines, only that it can be challenging to equate them in a meaningful way with perception and appropriately rank the importance of all this in the hierarchy of all the other stuff we need be concerned with.  Be aware, but don't fret too much and frighten oneself into neuroses.  Make sure your batteries are charged and the SD card has enough space.

From the FAQ at that site:

"Are most SRCs really that bad?
No. If you look at the decibel scale to the right from the graphs, you can see that the range of these graphs is very wide: down to -180 dB. The distortions generated by most properly designed SRCs are below -100 dB and can hardly create audible artifacts. However SRCs differ in the transition band of the low-pass filter and in the amount of pre-/post-echo and aliasing. The bottom line is that most tested SRCs range from fairly good to excellent, but the graphs are very sensitive to emphasize the differences."


Interesting to revisit that site again years later.  The thing most interesting to me now is looking at how many earlier versions of the same software performed considerably more poorly than their more current releases.

« Last Edit: October 16, 2020, 05:35:27 PM by Gutbucket »
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Offline Gutbucket

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #83 on: October 16, 2020, 05:30:09 PM »
Great discussion in this thread.  Thanks to all participating.

All the resampling talk gets me thinking of fancy dither routines.  OT to sample rate conversion, but not by much as it tends to go hand in hand with bit-depth reduction.  Has anyone here ever noticed the difference between the use of noise-shaped dither verses standard triangular dither in any actual real world listening situation? That is to say, without first amplifying to totally non-realistic listening levels at which no one could actually listen?  I feel good using standard triangular dither not only because I can't hear any difference in real world playback, but also because of those future generation mastering remixers who will be mining and combining all of our current stone age pulls.  ;)
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Offline kuba e

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #84 on: October 17, 2020, 07:05:00 AM »
I don't think anybody is actually doing that, though. I process at the depth/rate with which the recording was made. The conversion to 16/44.1 is basically the last step (except for tracking).
I was doing this  ;D. I was saving my recordings 24/44.1 as 16/44.1. Thanks to our friends who explained the quantization noise and the dither, I think I can say that my approach was not wrong with a little tolerance. Yes, this is not a pure procedure but the range of our audience recordings does not exceed 96db and the background noise is also high. By the way, my Nak300 have listed S/N as "higher than 50db weighted".

I would counter-argue that the constraints from limitations of the recording is limited more by taper knowledge and experience toying with post production (followed by frustration of not putting in the time to learn how to equalize and do ear training), rather than a limitation of the medium or method of recording.
I think this is a misunderstanding that Aaronji didn't mean it that way. My view is that most people here do audience recordings and these recordings are little bit rough. It's more difficult to learn to distinguish subtle details on rough recordings than on fine studio recordings. The learning is easier in the studio. We record as a hobby for joy. But this does not mean, that we don't appreciate any advice regarding theory and practice. I am grateful for your advices. They are valuable to me and broaden my horizons.
« Last Edit: October 17, 2020, 06:35:21 PM by kuba e »

Offline voltronic

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #85 on: October 17, 2020, 07:43:00 AM »
Some of you may be familiar with this website, which compares the performance of many different software sample-rate converters when converting from 96 kHz to 44.1 kHz.  See the Help section for details of the methodology and why they chose those rates to convert.  Some look nearly flawless; others atrocious.  Could you tell the difference in a blind test?

https://src.infinitewave.ca/

It is Halloween season.  Those scary looking sweep images may appear more frightful than they perhaps should be without an appropriate frame of reference.  Which is not to say there is no reason to use the better performing resampling routines, only that it can be challenging to equate them in a meaningful way with perception and appropriately rank the importance of all this in the hierarchy of all the other stuff we need be concerned with.  Be aware, but don't fret too much and frighten oneself into neuroses.  Make sure your batteries are charged and the SD card has enough space.

From the FAQ at that site:

"Are most SRCs really that bad?
No. If you look at the decibel scale to the right from the graphs, you can see that the range of these graphs is very wide: down to -180 dB. The distortions generated by most properly designed SRCs are below -100 dB and can hardly create audible artifacts. However SRCs differ in the transition band of the low-pass filter and in the amount of pre-/post-echo and aliasing. The bottom line is that most tested SRCs range from fairly good to excellent, but the graphs are very sensitive to emphasize the differences."


Interesting to revisit that site again years later.  The thing most interesting to me now is looking at how many earlier versions of the same software performed considerably more poorly than their more current releases.

Yes, I noticed the same thing about older versions of the same software.
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Offline jerryfreak

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Re: 48 kHz vs 44.1 kHz sample rate
« Reply #86 on: October 17, 2020, 05:44:39 PM »
wow thats quite illuminating. ive been using the izotope plugins in soundforge instead of the default SRCs and im glad i did!
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