Sound Quality Vs. Measurements

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Did you by chance keep records of the time required to bump the standard 16-bit WAVE format to higher levels? Just curious ...
Just to remind myself, I tried it again. I took a track from the 80's, what many people would regard as pop fluff, Dexy's Midnight Runners - Come on Eileen, which started as a 128kbps MP3, size of just under 4 Mbytes, 4 1/4 mins running time. Imported into Audacity, resampled to 384000 rate, exported as 24 bit WAV file. Resampling on Dell laptop took 1/2 hr with CPU at 90% usage, exporting took another 1/4 hr, final file size 571 Mbytes!!

But this silk purse project works, for me. Once the DAC had warmed up a bit, the difference between original and resampled was chalk and cheese. The MP3 is a scratchy, unpleasant mess, the hi res conversion had good tonality of the instruments, nice space rendition, depth, imaging, all the usual adjectives.

Sometimes, miracles are possible ... . Just wondering, whether anyone else has tried this bizarre exercise ...?

Frank
 
My view of this is that digital is another level of complexity which we too happily live with .

We can live on tinned food until eternity and probably be healthy if the food is correctly conceived . It is not the same as real food . I am not a vegetarian although I love vegetables . Meat is seldom much more than dead when I eat it . Other food to me is " digital " food .

We had a campaign for real ale in England . Beer as it was made for centuries especially if without hops . Some critics call it warm/ flat beer . Yes that is partially true 50 F ( 10 C ) is about the right serving temperature ( lower than red wines , higher than whites ) . Low grade beers do not taste good at 10 C . Now it is virtually impossible to buy beer which is not of this sort . The problems of going bad are never seen ( it was said rubbish beer kept better ) , more often the barrel runs out . This beer is alive to a certain extent and needs skillful management . It is also cheap considering the care taken .

Somehow digital has taken away some pride we once had .

Notice I didn't mention organic foods . I think they are better because the
producers care more because they are organic . Would be happy to be told analogue people care more .
 
Sometimes, miracles are possible ... .

No.

Just wondering, whether anyone else has tried this bizarre exercise ...?

Frank

It´s bizarre, indeed. Reading a 571 Mb file for playback would actually _increase_
the total system load (not that the system load would have an impact on sound quality like some believe).

The losses in MP3 occur during the _encoding_ stage, there is _no_ way to regain information which was discarded in the first place.
 
I remember years ago that it was said the errors of digital are predictable which means restoration is is possible . Micheal Gerzon pointed out that not all errors are . Some of the errors off early digital might be analogue . If so keeping some note of circuits will be important .

It was said years ago that if certain functions in digital circuits were done by circuits known to be poor in analogue then similar sonic traits were noted . I don't know as I never tried . The critics saying that it was harder to prove if digital . His statement was if it works well in analogue it should be used where practical in digital . I suspect it is hype . However a sensible bit of caution .

Tamla Motown digitally mastered their collection and got rid of the master tapes I think I read ? That was in the days of early digital ( Sony PCMF 1 ) . Hope you are right Frank . Digitally remastered . I understand it , however feel they over play it . Digitally offer if more truthfully . Fact that a vinyl master would sound wrong has nothing to do with it . It is implied that the vinyl master was inferior . No , like colour photography there was/is some processing .
 
In engineering especially, the overall optimum may, and in reality very often does, mean that for the sake of achieving the optimum point for the whole, subsystems may have to be purposely moved away from what may be their own subsystem optimum.

No, I disagree - your example was an example of brand politics/marketing rather than engineering optimisation.

You cited that the compromise was made for 'sales optimum' - that's just a number. A number is without value - hence this was done because bean counters had to be placated. Separating the engineering design from the marketing would lead to the same result - compromise, and probably this split personality effect is present in abundance in GM's culture.
 
1) the mp3 player has a worse mp3 decoder than audacity (mp3 encoding is a standard. mp3 decoding is not)

2) the dac performs better when fed 384 KHz 24 bps signal

those are two reasons i think would make them sound different.

but without an ABX test we can not be sure there even exists a differece
 
The losses in MP3 occur during the _encoding_ stage, there is _no_ way to regain information which was discarded in the first place.
Information is NOT being gained through resampling, rather the replay process makes a mess of unraveling the detail, which has not been lost, when it tries to both decode the compression and have the DAC do the oversampling necessary to internally handle the lower sample rate of conventional WAV.


That's at least how I interpret these results, which I'm sure will vary from m/c to m/c. The better the quality of the soundcard, probably the less the discrepancy.

I've done this "trick" also on jazz tracks, and classical, and the audible benefits are heard every time.

Frank
 
A bit of history .

http://www.aes.org/aeshc/pdf/fine_dawn-of-digital.pdf
I note the first commercial digital was Decca . 18 bit 48kHz it is said . It was a paper thin recording which might have been the acoustics ? BBC 13 bit was/is excellent and enjoyed by many for years before CD . As Julian Vereker I think said , why didn't Philips choose that ?

There is I suspect an error in the text . The wartime scrambling was by using identical noise discs for encoding and decoding ( I think a Vocoder as used by musicians ) . These discs were periodically replaced . It seems that the U boats could simply listen to trans Atlantic cables .
 
fas42 said:
Information is NOT being gained through resampling, rather the replay process makes a mess of unraveling the detail, which has not been lost, when it tries to both decode the compression and have the DAC do the oversampling necessary to internally handle the lower sample rate of conventional WAV.
As others have said, MP3 throws away information. That information is lost. The remaining information is then encoded. A good MP3 decoder may produce more of the unlost information than a poor decoder but it can't recover the lost information. The best that can be done is to guess what the lost information might be from what has not been lost, but this is basically replacing music with musically-sounding-artifacts. It might even sound better, but it is not recovering lost detail.

Perhaps 'replacing music with musically-sounding-artifacts' is a description of how MP3 works! You certainly don't get an output signal which looks/measures anything like the input signal.
 
Just to remind myself, I tried it again. I took a track from the 80's, what many people would regard as pop fluff, Dexy's Midnight Runners - Come on Eileen, which started as a 128kbps MP3, size of just under 4 Mbytes, 4 1/4 mins running time. Imported into Audacity, resampled to 384000 rate, exported as 24 bit WAV file. Resampling on Dell laptop took 1/2 hr with CPU at 90% usage, exporting took another 1/4 hr, final file size 571 Mbytes!!

But this silk purse project works, for me. Once the DAC had warmed up a bit, the difference between original and resampled was chalk and cheese. The MP3 is a scratchy, unpleasant mess, the hi res conversion had good tonality of the instruments, nice space rendition, depth, imaging, all the usual adjectives.

Sometimes, miracles are possible ... . Just wondering, whether anyone else has tried this bizarre exercise ...?

Frank

Thank you, Frank.

Personally, I haven't tried anything like it myself, because I see no sense or possible gain in upsampling a signal which has already had a part of it thrown away, as MP3 does. "Thrown away" means forever lost.

The difference in sound quality you note I'd attribute to better DAC operation, because I don't see any other possible answer (which is not to say there is none).
 
No, I disagree - your example was an example of brand politics/marketing rather than engineering optimisation.

You cited that the compromise was made for 'sales optimum' - that's just a number. A number is without value - hence this was done because bean counters had to be placated. Separating the engineering design from the marketing would lead to the same result - compromise, and probably this split personality effect is present in abundance in GM's culture.

Disagree all you like, but it is a fact that in this case, the system is optimal if it satisfies the output goal, which is sales. And it does.

Despite the fact that the product is suboptimal technically. If it were the other way around, it would have been technically optimal and too expensive to compete, and would hence be suboptimal overall.

As for sales figures being just "numbers", well, you should try to explain that to the thousands of people working to make it happen, I feel relative sure that to them, it's a hell of a lot more than just a "number". To them, it's their job, their livelyhood. Also, I'd point out that since Chevrolet is only one of GM's divisions, these "numbers" also have influence on the macrosystem called GM as much more than just "numbers".

The only thing I agree with you is that there is much internal politics in deciding what is the optimal performance of this system; unfortunately, GM has not one but TWO divisions operating on the same markets, and are thus competing with themselves, like it or not. This does impose certain constraints on making purely engineering decisions, to be sure.
 
Disagree all you like, but it is a fact that in this case, the system is optimal if it satisfies the output goal, which is sales. And it does.

Then we must mean different things by 'optimal'. Fair enough.

As for sales figures being just "numbers", well, you should try to explain that to the thousands of people working to make it happen, I feel relative sure that to them, it's a hell of a lot more than just a "number". To them, it's their job, their livelyhood.

Well a true optimisation would take account of these people's happiness too, unlike your compromise solution.

The only thing I agree with you is that there is much internal politics in deciding what is the optimal performance of this system

More evidence that our meanings of 'optimal' differ - mine is not subject to opinion like yours.

; unfortunately, GM has not one but TWO divisions operating on the same markets, and are thus competing with themselves, like it or not.

Why is that 'unfortunate' ? Do GM's senior management see it the same way?

This does impose certain constraints on making purely engineering decisions, to be sure.

Which sounds as though you are now agreeing with me :)
 
When looking at music on an oscilloscope years before digital I was always struck by how simple the waves looked in comparison to the complex sounds I heard . I guess we detect start and stop points and we also recreate the sounds we hear from information clues ? I was told that speech was almost impossible for computers to comprehended in the early days . Not a question of clear speaking . The computer could not detect words . The gaps we hear so clearly are not apparent . I can reasonably cope in French . I find French films more difficult than real life especially after digital . I watched a film called Life is just one long tranquil river ( my translation and not precise ) . I understood it better than usual . Then I twigged it , Lille , I learned my French in Tournai some 9 miles away . I also learned in the south . Parisian French , not a chance . Great film .

https://en.wikipedia.org/wiki/Life_Is_a_Long_Quiet_River

BTW , big river .

https://www.youtube.com/watch?v=5AWCdZtX-2U&feature=related
 
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Thank you, Frank.

Personally, I haven't tried anything like it myself, because I see no sense or possible gain in upsampling a signal which has already had a part of it thrown away, as MP3 does. "Thrown away" means forever lost.

The difference in sound quality you note I'd attribute to better DAC operation, because I don't see any other possible answer (which is not to say there is none).


If I am right that about start and stop points then perhaps that is what is being better defined ? The ear I was told ( Oxford University ) seemed to be a very low quality analogue device with digital back up . A very fast signal returns from the brain which they had no idea as to it's function . I suggested a servo loop . I supplied a pair of selected KEF T27 with above 40 kHz ability for the tests .

http://www.jneurosci.org/content/19/19/8704.full.pdf
 
Looks like I'm going to have to repeat some of the experiments I did a year or 2 ago. I was playing with LAME, attempting to squeeze the last ounce of quality out of encoding to MP3, and I was quite impressed with what could be achieved -- there were subtle differences but you had to really concentrate to be aware of the variations. Plus, I seem to remember I could get the difference file to almost 60dB down, does that seem reasonable?

What I might do is grab a very well recorded hi res file, encode with LAME as best I can to 320, and 128 rates, then reverse the process in Audacity as I described in the earlier posts, and finally listen to all versions on the PC speakers. Will be interesting to see what comes up ...

Also, would be fascinating if someone else, please, tried doing this and what they come up with ...

Frank
 
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