[*Scotty*]

It might be worth while for fans of Hi-Rez recordings to examine the Hi-Rez files they have downloaded with some sort of spectrographic analysis program and see if they actually have a Hi-Rez recording or something just masquerading as a Hi-Rez recording via resampling.
 Many recordings are mastered at 24/48 and a great number of them are upsampled to 24/96 or 24/192 and then sold as mastered at 24/96 or higher when spectrographic analysis clearly shows a 48 kHz original sampling frequency. Spectrographic analysis will show a sharp cut off of the frequency spectrum above half the of the original sample frequency, in the case of a 48kHz sampling frequency this will be a sharp horizontal line at 24khz with nothing appearing above the line. An actual 24/96 recording will show the clear presence of ultrasonic frequencies, sometimes higher than 35kHz with no sharp cutoff at 22.1 or 24kHz..
 Unfortunately, in a great many cases we may not be getting what we thought we paid for.
I use the free program Spek ( Spek-Acoustic Spectrum Analyzer) and Audacity recording and editing software. The results are not too difficult to interpret and a little online research will make some of the resulting spectrographs easier to figure out.
Here is a link to the Spek website. http://spek.cc/


The above image is a spek generated spectrogram of a 24/96 file with clear ultrasonic content above 24kHz indicating that this most likely has the 24/96 mastering claimed.
Image Below From Positive Feedback   Audacity generated

Here is a spectrogram of a 24/88.2 music file with authentic ultrasonic frequencies.


From Positive Feedback
Here is a spectrogram of a 24/96 music file with a brick-wall filter at 24kHz which is what must be used with an original sample rate of 48khz.
Spectrogram generated by Audacity free program for editing and recording download at http://audacityteam.org/
Link to positive feedback article "Are Your High Resolution Recordings Really High Resolution?"
http://www.positive-feedback.com/Issue60/hirez.htm
Please pay particular attention to Setting up Audacity to Confirm Frequency Response of Downloaded Files in the article. Preferences are found at the bottom of the drop down menu under Edit in Audacity. I set my preferences for Spectrogram at a maximum frequency of 48kHz which half of 96kHz and left the other parameters unchanged. In the unlikely event that you actually encounter a 24/192 recording you can change the maximum frequency to 96kHz.
Scotty

[PMAT]

Wow, very cool.

[*Scotty*]

I should mention that the spek program is just a point and shoot operation with no setup required, it appears to be able to analyze almost any type of file except for a DSF SACD rip. I Audacity to try to figure out what I am seeing in a spectrogram from the spek program. i will use Audacity's FFT analysis capability take a different look at the ultrasonic content. I am not saying that i always understand what I am seeing but another tool is sometime useful.
Scotty

[ted_b]

Scotty, You do know that this hirez spectral analysis is all over this forum and others (just do a search here on "Audacity" and you'll see the dozens and dozens of hirez releases that are constantly put through the tool). ?  It is what started, back in 2010, the questioning of HDtracks and their provenance.  So much so that they began to pull certain albums from their site.  Computer Audiophile dot com had so many of these threads that Chris created a sub forum called Music Analysis.  Audacity became the de rigueur tool, but many pro guys claim it is very inaccurate.

Scotty, I may merge this thread with one of the many others out there, or simply add your comments to one like this one started in 2011 "Show Me Your HiRez".
http://www.audiocircle.com/index.php?topic=91193.0

Thanks.

[*Scotty*]

Yeah Ted, works for me, if it's a dead horse here merge it or delete it. I didn't see any recent comments on the thread and I didn't do a search for Audacity.
 Sorry to waste peoples time.
Scotty

[ted_b]

Scotty, not a waste at all, just a duplication.  It is good detective work to find faux hirez stuff.

[JohnR]

Does this apply to DSD also? I'm assuming that a conversion step would be needed first (DSD->PCM)?

[ted_b]

Does this apply to DSD also? I'm assuming that a conversion step would be needed first (DSD->PCM)?

Correct, to do spectral analysis on DSD material (via Audacity or other consumer friendly SA tools) it needs to be converted to a supported PCM format.

[mikeeastman]

I have a question on Audacity, hope it ok to ask here. I want to make playlist of songs to do AB comparisons with,I only want 1 min of each song, I was going to use Audacity to edit the music but it appears that audacity is limited to 16 48 and I would like at least 24 196. I’m i wrong on the limits of Audacity? Is there and editing program that will do 24 192.

[ted_b]

Audacity can handle 24/192 files just fine.  Here is a screencap of the waveform and spectrum of a 24/192 FLAC Casssandra Wilson cut from New Moon Daughter.

[mikeeastman]

Great, thanks Ted.