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Old 18 October 2016, 20:32   #117
son of 68k
meynaf's Avatar
Join Date: Nov 2007
Location: Lyon / France
Age: 45
Posts: 2,879
Originally Posted by pandy71 View Post
This completely not true - this is simple conclusion after your last comments. I never wrote about poor Amiga audio quality and it was not me suggesting that i never hear Amiga.
I'm vaccinated and immune to FUD.
So you never write about poor Amiga audio quality. But you still wrote that it just can't do 14 bit, that it's closer to 10. You say there is noise, which not only me but several other ppl here don't hear (even when formatting floppies, lol). And you didn't disagree with anyone saying it was crap (my bold quotes).
However if you're vaccinated then why not just stopping here and try to discuss something more interesting.

Originally Posted by pandy71 View Post
Not sure if your ears are different than average human however human auditory system constantly changing and depends even from current weather... lot of factors affecting our perception and as such there is no reference hearing as such it is quite important to me to find which approach to play HQ audio samples is better for Amiga - or oversampled 8 bit with dithering and aggressive noiseshaping or 14 bit quasi-uniformly distributed PCM like current audio.
Of course ears differ about perception of small details. But big noise is big noise for everyone, isn't it ?
If you want to experiment oversampled 8 bit with dithering and aggressive noiseshaping, you can tell me exactly what computations have to be made on the signal, and i can try coding it. I have the code (somewhere) to play audio by cpu poking AUDxDAT.

Originally Posted by pandy71 View Post
OK let assume that you are right and sound quality can't be measured (not true) but audio circuits used for sound reproduction can be measured.
I hope you not suggesting that bad audio circuit with poor measurement results will provide good sound quality - however if you think it is true i will be glad of some examples for such situation.
Accuracy can be measured and indirectly can be used to quality assessment. I hope you not trying to suggest that Amiga is somehow high end audiophile source.
Ok so you want to measure sound quality. But, perfect accuracy in comparison to the digital signal, wouldn't lead to quality. The replay frequency itself (and preferably its harmonics as well) must be removed from the sound (aka anti-aliasing), so it won't be 'accurate'. I doubt any output in the world do exactly what the numbers say : if the samples say f.e. 1,3,5, values 2 and 4 should and will be observed in the output.
So with all this, what do you want to do ?

Originally Posted by pandy71 View Post
Once again i highly recommend -
He (Floyd E. Toole, Ph.D.
Vice President Acoustical Engineering, Harman International Industries, Inc) cover some of things you wrote about measure, science, theory - there is no electronics there but rather sound quality remarks and how subjective testing is complementary to objective, it is nice paper written with simple and understandable language - you may find it interesting.
Didn't i read that already ? Oh well, i'll take the time to check that again.

Originally Posted by pandy71 View Post
Modern PC very frequently outperform even theoretical 14 bit Amiga quality. You can subtract PC input noise, just use well defined high quality source like CD player or DVD (media player) - i can provide you samples with any resolution and sample rate you wish. By simple comparison it will be possible to at least assess if Amiga is worse/same/better than other known source. As a audiophile you probably have plenty high quality sources to use. I would say this rather problem of a good will than technical.
Well, looking again, it seems my PC has no RCA input. And even though it can perhaps outperform 14 bit, it's still just 16. Input A/D may filter or otherwise damage the signal. Rather than a PC, an oscilloscope may give better results - with samples tuned for that use - but i am not equiped.

Originally Posted by pandy71 View Post
There is no affordable accelerator for A500 i can buy. Software - do you have any proposal? (i have some hope that your software to avoid any doubts that i'm unfair and trying bias result by my point of view will be used).
I have written a program that can play wav, aiff, and flac (and mp3, and even ogg if i enable them). Custom versions can be made for different output comparisons. However you won't be able to use it on A500 and i'm not sure tests made on an emulator can be meaningful.

Originally Posted by pandy71 View Post
Nope and that's what i've wrote about misleading - my point is that every part of circuitry even not directly related with audio will affect audio signal quality, you constantly says that you feed 16 bit samples, and after shifting there is 14 bits (calibrated) of signal and as such from my perspective this translate (your words about 14 bits) to somewhere around 86dB SNR and comparable IMD/THD.
I'm not saying every part of circuitry can't affect audio signal. I know they can.
But having plugged it into some big amp where normal music with volume knob set to 8 would have been enough to make the neighbors come, i set it to 40 and still got only silence. Let's be honest : i was very surprised to hear nothing !

Maybe you're right and it's not good by todays standard. Yet it sounds good in everyday life.
If you play 24-bit samples on super accurate 24-bit D/A, will you hear the difference with regular 16-bit ? Where's the point in which it starts to count ?
If 14-bit doesn't sound different than 12-bit then maybe we only have 12-bit dynamics while playing 14. But then whether we have 12,14,16 or more, doesn't matter (at least for me).

Originally Posted by pandy71 View Post
Why i should stop talking with you? I assume you are mature (you 43 me 45) to have sane discussion where we are able to present different point of view, where there is a place for exchanging arguments and where at some point we can discuss some objective data and as a programmer you (i hope) appreciate that 2+2 will give you 4.
Weren't you the one with the proposal to stop talking ?

Anyway, we have to remember that we communicate in english, which i don't regard as a very good tool, especially when neither is a native speaker.
So many misunderstandings can occur.
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