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Are high sample rates better for DSP?
Ethan Winer
post Jun 10 2012, 20:13
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I've read many times that audio plug-ins such as equalizers work better at higher sample rates, even if audio generally doesn't benefit. It seems unlikely that there's a practical advantage to up-sampling all your files, or recording at 96 KHz in the first place, but is there a potential theoretical improvement? Or is this just another Internet myth?

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greynol
post Jun 12 2012, 17:59
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I know the unofficial mantra around here is all things sound the same unless proven otherwise, but all I can say is wow, just wow. When I was an engineer we always joked about something working on an infinite sample of one.

You've tested a couple of DSP operations on extremely trivial single-tone samples and are now willing to make such a sweeping generalization?!? I hope you don't plan on presenting this in public as things might get more than a little embarrassing for you. smile.gif

This post has been edited by greynol: Jun 12 2012, 18:48


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Ethan Winer
post Jun 12 2012, 19:35
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QUOTE (greynol @ Jun 12 2012, 12:59) *
You've tested a couple of DSP operations on extremely trivial single-tone samples and are now willing to make such a sweeping generalization?!?

No plans to present this in public. I posted this question because a friend asked me about it and I wasn't sure, so I figured I'd ask the experts. Me, I'll be satisfied to hear a good explanation of why EQ works better on 96 KHz audio files than files at 44.1 KHz. I'll be even happier to see an FFT or other data, or even a pair of audio files to compare. Whaddya got? biggrin.gif

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saratoga
post Jun 12 2012, 21:12
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QUOTE (Ethan Winer @ Jun 12 2012, 14:35) *
Me, I'll be satisfied to hear a good explanation of why EQ works better on 96 KHz audio files than files at 44.1 KHz.


Resampling is accomplished by applying a filter. If you resample to a higher sampling rate, then apply an EQ, effectively the length of the filter in the EQ is expanded by the length of the filter in the resampler. Thus, you're essentially using a filter with more taps, which if properly designed (e.g. a good resampler), will give 'better' (or at least different) results then a filter with fewer taps.

Of course if the EQ is already properly designed for its application, changing it is unlikely to improve things.
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Ethan Winer
post Jun 12 2012, 22:46
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Thanks Drew for some hard evidence. Can you explain in layman's terms what the difference is between the two files after applying the same EQ? From the partial graph it looks like there's more boost at 10 KHz, but that doesn't seem right.

QUOTE (saratoga @ Jun 12 2012, 16:12) *
Of course if the EQ is already properly designed for its application, changing it is unlikely to improve things.

I guess this is the crux of it. Are many/most EQ plug-ins written "properly" such that there's no practical advantage to using files recorded at higher sample rates? Does the Sonitus that drew (and I) use do things properly?

As you know, my perspective is what matters in practice. For example, in theory 0.0001 percent distortion is "better" than 0.001 percent, but in practice it doesn't make even a tiny audible difference because both are too soft to hear. I've been using EQ plug-ins for years, and I've never noticed any degradation, or change to the audio other than the EQ I applied.

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drewfx
post Jun 13 2012, 01:52
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QUOTE (Ethan Winer @ Jun 12 2012, 17:46) *
Thanks Drew for some hard evidence. Can you explain in layman's terms what the difference is between the two files after applying the same EQ? From the partial graph it looks like there's more boost at 10 KHz, but that doesn't seem right.


The 192kHz (orange) was about +6dB on the spectrum analyzer before the EQ was applied. I turned off the pre-EQ snapshots to make things easier to see, but they were essentially straight lines ~6dB apart.

Basically, the 2 curves are quite different at >15kHz, but you can also see the Q at 10kHz is a little different as well. For the part below 6kHz (covered by the EQ) they appear identical (~6dB apart).

So it's just a somewhat different EQ curve being applied in this case.

And you might note that the 48kHz curve in the analyzer arguably looks more like the curve in the EQ GUI anyway. smile.gif
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andy o
post Jun 13 2012, 03:27
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I'm guessing these are the reasons why A/V receivers and such oversample for DSP?
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Arnold B. Kruege...
post Jun 25 2012, 13:10
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QUOTE (andy o @ Jun 12 2012, 22:27) *
I'm guessing these are the reasons why A/V receivers and such oversample for DSP?


Do they?
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Woodinville
post Jun 27 2012, 21:59
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QUOTE (Arnold B. Krueger @ Jun 25 2012, 05:10) *
QUOTE (andy o @ Jun 12 2012, 22:27) *
I'm guessing these are the reasons why A/V receivers and such oversample for DSP?


Do they?


I'm aware of some that do nonlinearities that do not oversample, and have a disaster as a result. That's not quite what you asked, of course.


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Posts in this topic
- Ethan Winer   Are high sample rates better for DSP?   Jun 10 2012, 20:13
- - knutinh   The higher the sample-rate, the better any approxi...   Jun 10 2012, 20:46
- - lvqcl   Here is an example of such filter (with explanatio...   Jun 10 2012, 20:56
- - benski   Yes, many filters work better with higher sampling...   Jun 10 2012, 21:17
|- - Ethan Winer   QUOTE (knutinh @ Jun 10 2012, 15:46) The ...   Jun 11 2012, 17:18
|- - saratoga   If your software is good, it should be upsampling ...   Jun 11 2012, 17:53
|- - drewfx   QUOTE (Ethan Winer @ Jun 11 2012, 12:18) ...   Jun 11 2012, 19:11
|- - Ethan Winer   QUOTE (saratoga @ Jun 11 2012, 12:53) If ...   Jun 12 2012, 17:46
|- - extrabigmehdi   QUOTE (Ethan Winer @ Jun 12 2012, 16:46) ...   Jun 12 2012, 18:15
- - xnor   Many EQs use simple bilinear-transformed filters (...   Jun 11 2012, 01:37
- - Woodinville   In addition to the warping one sees in a bilinear ...   Jun 11 2012, 01:46
- - extrabigmehdi   That's interesting, so basically if you want ...   Jun 11 2012, 02:30
- - bandpass   QUOTE (knutinh @ Jun 10 2012, 20:46) The ...   Jun 11 2012, 08:00
|- - knutinh   QUOTE (bandpass @ Jun 11 2012, 09:00) Tru...   Jun 11 2012, 08:30
- - bandpass   From a practical perspective, a particular effect/...   Jun 11 2012, 09:59
|- - knutinh   QUOTE (bandpass @ Jun 11 2012, 10:59) ......   Jun 11 2012, 11:55
- - greynol   I know the unofficial mantra around here is all th...   Jun 12 2012, 17:59
|- - Ethan Winer   QUOTE (greynol @ Jun 12 2012, 12:59) You...   Jun 12 2012, 19:35
|- - drewfx   QUOTE (Ethan Winer @ Jun 12 2012, 14:35) ...   Jun 12 2012, 20:29
|- - saratoga   QUOTE (Ethan Winer @ Jun 12 2012, 14:35) ...   Jun 12 2012, 21:12
|- - Ethan Winer   Thanks Drew for some hard evidence. Can you explai...   Jun 12 2012, 22:46
||- - benski   It's mostly that the shape (aka Q) is going to...   Jun 12 2012, 23:39
||- - drewfx   QUOTE (Ethan Winer @ Jun 12 2012, 17:46) ...   Jun 13 2012, 01:52
||- - andy o   I'm guessing these are the reasons why A/V rec...   Jun 13 2012, 03:27
|||- - Arnold B. Krueger   QUOTE (andy o @ Jun 12 2012, 22:27) I...   Jun 25 2012, 13:10
|||- - Woodinville   QUOTE (Arnold B. Krueger @ Jun 25 2012, 05...   Jun 27 2012, 21:59
||- - Ethan Winer   QUOTE (drewfx @ Jun 12 2012, 20:52) The 1...   Jun 13 2012, 19:55
|- - Woodinville   QUOTE (saratoga @ Jun 12 2012, 13:12) QUO...   Jun 13 2012, 01:22
- - greynol   Have you read the responses to your topic? I want...   Jun 12 2012, 19:42
- - greynol   As for the "it's best to record at 96kHz ...   Jun 13 2012, 00:53


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