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Badly drawn waveforms vs. the audio that’s actually output—filters etc, Split from: Jplay - just another scam? Topic ID: 92856
Wombat
post Feb 14 2012, 16:37
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QUOTE (JimH @ Feb 9 2012, 16:44) *
Cross posting a jplay thread on the computeraudiophile forum. I finally had to say something last night.

http://www.computeraudiophile.com/content/...#comment-127258

I used the M word.

I just did read over the thread at computeraudiophile.
Seems like all comes down to the better RAM handling changing the sound to the positive. So the claim is that inside the same plattform using jplay changes the way even a asynchronous attached device gets its buffer filled.
This at least should be to measure but isn´t for some reason.
My understaning of this implies that every single processor/RAM/platform implementation must sound different which is a problem.

This of cause has to lead to only one possible conclusion: PC based sound playback doesn´t work and should be considered a dead end, there are to many variables at play smile.gif

When i imagine myself to be a software developer like you JimH, that did spend endless hours of his life to develop a complete suite that grew over many years i´d really had to wonder. Isn´t it much easier to code some esotheric code that prevents bit-rot* and demanding twice the money for it?

When you have some time and read over the forum there are several threads that have strange reasoning. This one for example:
http://www.computeraudiophile.com/content/Why-2496-not-24192
They even use scientific pictures wink.gif
It must be said there are of course several people knowing their stuff.

* bit-rot is a term i learned lately and describes the audiophile problem that happens on computer playback all the time
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andy o
post Feb 14 2012, 17:20
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Is it possible to explain non-mathematically (or just a little) why this linked from Wombat's link is wrong? I know it is, just don't understand it very well.

This is one of the pictures accompanying the article:



QUOTE
I tested some 10 kHz and 20 kHz sine waves that were recorded at several word lengths (16 bit or 24 bit) and sampling frequencies (44.1 kHz, 96 kHz, 192 kHz), analyzing them in a software sequencer.

Isn't that just Audacity? I wonder if they "analyzed them in a software sequencer" to sound more professional.

This post has been edited by andy o: Feb 14 2012, 17:23
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andy o
post Feb 15 2012, 03:05
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This seems very obvious, but I'll ask anyway. Has anyone made an actual wave that looks like that (I assume it can't look exactly like it), and played it alongside that misrepresentation of a 44.1kHz sine? They should sound completely different, shouldn't they?
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Arnold B. Kruege...
post Feb 15 2012, 13:50
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QUOTE (andy o @ Feb 14 2012, 21:05) *
This seems very obvious, but I'll ask anyway. Has anyone made an actual wave that looks like that (I assume it can't look exactly like it), and played it alongside that misrepresentation of a 44.1kHz sine? They should sound completely different, shouldn't they?


If you wanted to make a wave that looks like the Audacity fictional waves, you'd have to use a far higher sample rate because the rounding that proper wave display programs like Audition provide is the result of applying the effects of an ideal brick wall filter ("sinc filter").

That means that the weirdness from Audacity is a consequence of something very much like a DAC that lacks a reconstruction filter. DAC's that lack a proper reconstruction filter are the rage among some audiophiles. I know of no DBTs comparing DACs the same resistor ladder with and without proper brick wall reconstruction filtering.

I can speculate with some technical support that there probably isn't an audible difference due to the presence or non-presence of a reconstruction filter, as long as the equipment downstream from the DAC has low nonlinear distortion. As a rule I would expect that they would sound very similar unless significantly nonlinear equipment were used for monitoring. Of course, SET amplifiers and some tweeters are significantly nonlinear.
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