Hi-rez to Redbook and back again ...

fas42

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Just curious and perhaps it's already been asked or mention made of it ...

Has there been any substantial testing of a "difficult" track recorded in good quality Hi-rez, which is next transferred to Redbook, and then upsampled from that back to the same Hi-rez format to create effectively a second generation digital copy of the original, and then comparisons made?

I'm talking here of doing "proper" AB testing of the original and digital copy from a music server through the best DAC to see if people can pick an audible difference ...

Frank
 

Bruce B

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I thought this was the whole premise of the MM paper.
I'd certainly be willing to put up some samples of 2 hi-rez files, with one being the down/upsampled one for everyone to listen to.
So what "difficult" track would one propose? I'd probably start off with a quiet solo piano piece.
 

amirm

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I think it will be a fun exercise no matter if it has been tried. I suggest something with notes that decay to nothing. If the piano track has that, then it is good. Otherwise some quiet string guitar would be nice.
 

fas42

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Had a quick look at that paper, and it is not doing what I'm talking about. In that test the comparison is made while an extra layer of complex electronics is in operation, and that is exactly what has to be taken out of the equation. In other words, when doing the AB test the only electronics functioning at that moment is a music server with two tracks to be chosen between, a high quality DAC and high quality headphones. Absolutely nothing else is involved when doing the actual comparison!

Frank
 

garylkoh

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What Frank has proposed should be even more transparent than the "Meyer Moran" test. Some of the best upsampling/downsampling algorithms are two-pass, and hence not executable in real time. If Bruce does the downsampling/upsampling, I'm sure that he will do his best job, and I'll bet a that no one will be able to hear a difference - or to reliably ABX identify the tracks.

Publish your ABX logs!!
 

Phelonious Ponk

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I've decided not to trust myself with these kinds of tests. For one thing, I don't expect to hear a difference, so I probably won't. But more importantly, I just don't have the patience for it. What am I listening for? Did I hear a pre-echo (what exactly is a pre-echo?)? Was that reverb tail longer than the last one? Did it break up just before it faded to black? Wow, that guitar passage is gorgeous. What was I listening for again?

Maybe if the music really sucked I could care; anybody got any hi-res polka?. This much my listening has proven, to me, anyway: These differences, if they exist, are so small, that unless my system is otherwise perfect, and it's certainly not, I have much more important things to worry about.

Tim
 

Bruce B

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Here they are. Solo piano at 176.4
There are 3 tracks. Tell me which one/s has been down/upsampled! No cheating!!

Sample Tracks
 
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audioguy

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These differences, if they exist, are so small, that unless my system is otherwise perfect, and it's certainly not, I have much more important things to worry about.

Tim

+1

A friend and I call that the "squint factor". If you have to close your eyes (or almost close your eyes) and listen REALLY, REALLY, REALLY hard and you are STILL not 100% sure you heard a difference, invest your time and energy elsewhere. (like room treatment or digital room correction, or better yet, new music!!).

I have saved a ton of money by following that advice :):) (Except when I don't follow it)
 
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Bruce B

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I take it by the lack of responses that it's impossible to tell which file has undergone sample rate conversion?
 

amirm

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No, just laziness :). I haven't been near my workstation to do any tests yet. Thanks for producing the files :).
 

RBFC

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13 hours in the cardiac OR today. Guess that cuts into my listening time.... Thanks, though, Bruce. You really go out of your way to contribute cool stuff. I'll get to it.

Lee
 

fas42

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Guess you managed a lay down misere, Bruce! No-one is willing to own up that they can't pick a difference, or maybe they just don't want to know that they mightn't be able to do it ... :D

If people in general can't distinguish the two versions what does that then say about Redbook vs. Hi-rez? Hmmmm ....

Frank
 

Phelonious Ponk

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Guess you managed a lay down misere, Bruce! No-one is willing to own up that they can't pick a difference, or maybe they just don't want to know that they mightn't be able to do it ... :D

If people in general can't distinguish the two versions what does that then say about Redbook vs. Hi-rez? Hmmmm ....

Frank

Nothing that hasn't already been said. ;)

Tim
 

ted_b

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Feb 4, 2011
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Wow, Bruce although I only used my desktop rig (Audioengine 5's, onboard sound) I thought I easily could tell the difference..except I got it wrong!! :( (Audacity shows the culprit easily of course). I should have waited to put these on my Antelope Gold DAC, but..wow, you certainly didn't mess up the redbook one, it's still very nice. Maybe I'll have one of my kids rename them and then I'll put them on the main rig and try again.....
 

Steve Williams

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What I found interesting at the recent California Audio show was that in many of the rooms where hirez files were being played and then compared against the standard red book version, most people commented that they couldn't detect any audible difference at all.
 

Hipper

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Floyd Toole makes a good point in his Sound Reproduction book.

He suggests that there isn't a difference in the quality of the sound betwen redbook CD and SACD for identical recordings

When there is it's because more effort is put in to making a quality production by the recording engineer for SACD, because, firstly, presumably it attracts a premium price so they can afford to, and secondly SACDs are most likely to be listened to in a true Hi-Fi set up, whereas CDs could be heard anywhere - cars, walkman etc..
 

microstrip

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Floyd Toole makes a good point in his Sound Reproduction book.

He suggests that there isn't a difference in the quality of the sound betwen redbook CD and SACD for identical recordings

When there is it's because more effort is put in to making a quality production by the recording engineer for SACD, because, firstly, presumably it attracts a premium price so they can afford to, and secondly SACDs are most likely to be listened to in a true Hi-Fi set up, whereas CDs could be heard anywhere - cars, walkman etc..

Hipper,

Floyd Toole "Sound Reproduction" is a great book, but Floyd Toole does not state what your saying - he just quotes the conclusions of the Meyer and Moran test (page 443).
And the explanation presented for the fact that virtually all the SACDs and DVD-As sounded better does not exclude that they can also sound better because of the format itself or other reasons. It can be one of many.
 

Hipper

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You are right of course in much of what you say. I got it a bit muddled.

However, he writes that 'these tests concluded that high resolution recordings may sound better than CDs but not because they have high resolution'.

Reading the Meyer and Moran paper, I think Toole got that right.
 

LL21

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Here they are. Solo piano at 176.4
There are 3 tracks. Tell me which one/s has been down/upsampled! No cheating!!

Sample Tracks
i listened to each once...did not obsses about it...on my laptop with a fair amount of ambient noise. I liked Track 3 best...on 1 & 2, i found elements of 1 with slightly greater dynamic range than 2, but 2 sounded clearer around the delineation of notes. You'll probably say they were all identical! or 3 was a 2,000 generation copy of 1! ;)
 

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