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192kHz Samples -- But Not Really?

I'm looking to undertake several ABX tests across multiple participants in a short study, but am coming up short finding actual high-definition samples.

Spectral analysis of tracks I've acquired from HDTracks and other free-to-distribute sources have spectograms like these:

1. I've interpreted this as likely a Redbook CD quality source which has been upsampled.


2. And this one as a 96kHz source which has had some hijinx applied, explaining the high-frequency noise with nothing in the middle.


Could anyone please comment on the above, in particular whether they think I've misread these spectograms?

I would also appreciate if if anyone could direct me towards a genuine sample with high frequency content, suitable for this ABX testing, as I've so far come up empty. Even if these frequencies are patently inaudible, I need to give them a fair crack of the whip for the sake of fairness/good science.  :))

Many thanks!

Re: 192kHz Samples -- But Not Really?

Reply #1
2. Maybe it was converted from DSD?

Re: 192kHz Samples -- But Not Really?

Reply #2
Second one looks like noise shaping. I don't think it's DSD, there would be more extreme noise shaping and at much lower frequencies.

I think low pass filtering as in #2 is common, if you have too much high frequency energy you can get imd.  What are you hoping to test? Sampling rates? The effect of ultrasound? Both? 

Re: 192kHz Samples -- But Not Really?

Reply #3
Second one looks like noise shaping. I don't think it's DSD, there would be more extreme noise shaping and at much lower frequencies.

I think low pass filtering as in #2 is common, if you have too much high frequency energy you can get imd.  What are you hoping to test? Sampling rates? The effect of ultrasound? Both? 

I'm hoping to do an ABX test of 44.1 with 96/192kHz.

Re: 192kHz Samples -- But Not Really?

Reply #4
2. Maybe it was converted from DSD?
Look at the upper spectrum pattern carefully, especially somewhere after 7:00.
Looks like aliasing/mirroring/imaging to me.

Re: 192kHz Samples -- But Not Really?

Reply #5
I see changes in intensity, but not the type of changes in frequency that one would expect to be caused by aliasing/imaging.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?

Re: 192kHz Samples -- But Not Really?

Reply #6
If it helps, here is a link to the (freely distributable) sample of the second track. Does this look like 192kHz to you guys? I'm not sure how to interpret the Audacity spectrals/Spex results.

Does anyone know of an audio file (perhaps electronically generated for testing purposes) which includes the necessary frequencies up to 192kHz?

Many thanks.

Re: 192kHz Samples -- But Not Really?

Reply #7
The 2nd was originally recorded in DXD (352.8k 32bit, presumably with Pyramix)  It is noise shaped with the noise rising above the original recording somewhere about 50k (at least in the sections I looked at.)  All of the other resolutions at 2L.no's test page are also derived from DXD recordings.

Re: 192kHz Samples -- But Not Really?

Reply #8
Yes. 2L has a lot of samples up to DXD.
http://www.2l.no/hires/

But as long as they are acoustic recordings, very high frequencies are usually pretty weak and blended with the noise floor. In case you want to use 2L's samples, downsample the hi rez files to redbook yourself instead of using their files. Reason:

https://hydrogenaud.io/index.php/topic,111416.0.html

Generating a synthetic signal with a lot of HF is easy, but... are your participants self proclaimed audiophiles? They may not like this idea as it is not "real" stuff.

Re: 192kHz Samples -- But Not Really?

Reply #9
Generating a synthetic signal with a lot of HF is easy, but... are your participants self proclaimed audiophiles? They may not like this idea as it is not "real" stuff.

No, it's a lay audience. Do you guys know of any synthetic high-resolution electronic tracks? I've come across several which appear to be 44.1kHz upsampled (as per the first spectrogram above).

Re: 192kHz Samples -- But Not Really?

Reply #10
But as long as they are acoustic recordings, very high frequencies are usually pretty weak and blended with the noise floor. In case you want to use 2L's samples, downsample the hi rez files to redbook yourself instead of using their files.

Is there a preferred way of converting from DXD to PCM for 192/96/48/44 comparisons, given that the 192kHz samples on that page already seem heavily shaped/have strange high-frequency bands?

Re: 192kHz Samples -- But Not Really?

Reply #11
No, it's a lay audience. Do you guys know of any synthetic high-resolution electronic tracks? I've come across several which appear to be 44.1kHz upsampled (as per the first spectrogram above).

If you don't even need music... check the attached file.

Is there a preferred way of converting from DXD to PCM for 192/96/48/44 comparisons, given that the 192kHz samples on that page already seem heavily shaped/have strange high-frequency bands?

Resamplers like SoX and SSRC and many others will filter those noise, no special treatment needed.

Re: 192kHz Samples -- But Not Really?

Reply #12
Is there a preferred way of converting from DXD to PCM for 192/96/48/44 comparisons, given that the 192kHz samples on that page already seem heavily shaped/have strange high-frequency bands?
I suggest modified SoX by mansr at GitHub

Graph 2 may be the noise of a recent SDM ADC that operates at higher frequency and is multibit instead of the DSD64 you used to have seen.
Is troll-adiposity coming from feederism?
With 24bit music you can listen to silence much louder!

Re: 192kHz Samples -- But Not Really?

Reply #13
As quoted from our DSD decoder help file:

DSD has a sample rate of 2.8MHz, known as D64, or 5.6MHz (D128), but only 1 bit, which creates high frequency ultra sonic noise when decoded to 352KHz, or 704KHz. In-fact it is our understanding that SACD players are recommended to have a low-pass filter of 50KHz to filter out this high frequency noise (you cannot hear it, but your cat or dog might, also the tweeters on the speakers might run hot from it). By using 96KHz this noise is pretty much filtered. It is possible to decode to any number of frequencies, anything above 96KHz should use a low pass filter (DSP effect), ideally set to 48KHz.

Re: 192kHz Samples -- But Not Really?

Reply #14
Is there a preferred way of converting from DXD to PCM for 192/96/48/44 comparisons, given that the 192kHz samples on that page already seem heavily shaped/have strange high-frequency bands?
I suggest modified SoX by mansr at GitHub
Ops! I did misread DXD for DSD somehow. For DXD that is simple PCM use whatever you want. No modified SoX needed.
Is troll-adiposity coming from feederism?
With 24bit music you can listen to silence much louder!

Re: 192kHz Samples -- But Not Really?

Reply #15
If you don't even need music... check the attached file.

Unfortunately, given the broader experiment this is a part of, it would need to be music. It's not particularly important what kind, though. :)


I suggest modified SoX by mansr at GitHub

Is there a compiled version of Mansr's version? Unfortunately, I haven't the programming expertise to compile this. To your later post: Is DXD not a container for DSD?

As quoted from our DSD decoder help file:

DSD has a sample rate of 2.8MHz, known as D64, or 5.6MHz (D128), but only 1 bit, which creates high frequency ultra sonic noise when decoded to 352KHz, or 704KHz. In-fact it is our understanding that SACD players are recommended to have a low-pass filter of 50KHz to filter out this high frequency noise (you cannot hear it, but your cat or dog might, also the tweeters on the speakers might run hot from it). By using 96KHz this noise is pretty much filtered. It is possible to decode to any number of frequencies, anything above 96KHz should use a low pass filter (DSP effect), ideally set to 48KHz.

Very interesting to know, thank you for that information. Does this mean that most music recorded in ultra-high resolution DSD (e.g. 704kHz) has the bulk of its higher resolution (>50kHz) content stripped away by filtering?

Re: 192kHz Samples -- But Not Really?

Reply #16
DXD is 24bit/384kHz PCM. The term was introduced for recordings done in DSD but for processing or distribution converted to this high bitrate PCM.
Is troll-adiposity coming from feederism?
With 24bit music you can listen to silence much louder!

Re: 192kHz Samples -- But Not Really?

Reply #17
Very interesting to know, thank you for that information. Does this mean that most music recorded in ultra-high resolution DSD (e.g. 704kHz) has the bulk of its higher resolution (>50kHz) content stripped away by filtering?
http://www.merging.com/uploads/assets/Merging_pdfs/dxd_Resolution_v3.5.pdf
"DXD is defined as a 24-bit signal sampled at 352.8kHz"
You can read the whole pdf and get more information.

DXD is PCM. So just use any popular resampler with good reputation. 2L didn't filter those noise, why should you? I just complained they didn't carefully time align different files, but not other things.

The whole thread should have nothing to do with DSD. While DSD is hi-res, non-DSD doesn't mean non hi-res. In 2L's samples, if it specifies DXD is the source of recording, unless you choose to test the DSD files, it has nothing to do with DSD at all.

Re: 192kHz Samples -- But Not Really?

Reply #18
http://www.merging.com/uploads/assets/Merging_pdfs/dxd_Resolution_v3.5.pdf
"DXD is defined as a 24-bit signal sampled at 352.8kHz"
You can read the whole pdf and get more information.
Absolutely correct. Not my day today, i better stop posting here.
Is troll-adiposity coming from feederism?
With 24bit music you can listen to silence much louder!

Re: 192kHz Samples -- But Not Really?

Reply #19
While DSD is hi-res, non-DSD doesn't mean non hi-res.
Non-DSD but still hi-res should also include CDDA.
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?


Re: 192kHz Samples -- But Not Really?

Reply #21
Why give the term away so freely...

...especially to an unscrupulous corporation?

I don't give a rat's ass about a stupid logo, but is the term trademarked or something?
Is 24-bit/192kHz good enough for your lo-fi vinyl, or do you need 32/384?


Re: 192kHz Samples -- But Not Really?

Reply #23
Unfortunately, given the broader experiment this is a part of, it would need to be music. It's not particularly important what kind, though. :)

Chiptunes must be music, right?
http://www.foobar2000.org/components/view/foo_gep

I don't know if you familiar with these stuff or not, the plugin emulates the sound of old game consoles, and you need to find the chiptunes files yourself. You can render the output to any sample rate you like, but for ABX, don't render files at different sample rates separately because it may create differences below 20kHz. You should render at your highest target (e.g. 192kHz) and downsample it to 44kHz for example.

NSF (Nintendo) and HES (PC-Engine) formats are good choices for your test.

Re: 192kHz Samples -- But Not Really?

Reply #24
Most of the chip formats supported by foo_gep low pass filter at hard configured rates, depending on the sample rate and on the console being emulated.

 
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