On Sun, Jan 9, 2022 at 1:01 AM Nigel Redmon <earle...@earlevel.com> wrote:
> no i think Sampo was wanting to introduce 'subtractive dither' as a > solution, not additive dither - but please correct me if i'm wrong. not > sure about the historical development of dither but i have heard that the > original idea for dither was conceived during WWII when German warplanes > would have problems with the gear assembly becoming stuck, and lubricant > would not help. instead what helped was the occasional random bump to the > gear assembly to help jar things loose and keep things running smoothly > > > Right, but I didn’t state that in error. Let me put it this way: > > If the easy and accepted solution isn’t actually needed (because it can’t > be reproduce, or heard—again, I’m limiting my comment to 24-bit, which is > widely streamed these days), what is the point of a more complex solution? > why is the dither in 24-bit streamed audio 'not reproduced' or not 'heard' ? > > Im not saying the idea is useless. It’s just commercially useless when > it’s already trivial to stream uncompressed 24-bit (the cost of my Apple > Music subscription didn’t change a cent when they switched to uncompressed > 24-bit), which has limits that are already below audibility and physical > limits of electronics. > > > On Jan 8, 2022, at 9:11 PM, Zhiguang Zhang <ericzh...@gmail.com> wrote: > > > On Sat, Jan 8, 2022 at 10:13 PM Nigel Redmon <earle...@earlevel.com> > wrote: > >> >> If you can’t hear it, or reproduce it—and at 24-bit you get both—you >> can’t hear it. >> > >> > Amplify the noise to 60dB SPL and let me me introduce my favourite test >> signal. Absent subtractive dither, I can introduce audible intermodulation >> products. Even if not amplified, intermodulation products tend to creep up >> off the noise floor, if stable enough. >> >> Well…in a few of these items you seem to be accepting my points about >> 24-bit…then say things like bring that noise floor up to 60 dB SPL, a >> measure to circumvent the 24-bit playing field, and shortcoming of >> electronics and human hearing. I’m not sure if you’re pulling my leg :-D, >> but this no longer has much to do with delivering music. Bring the noise >> floor to up 60 dB SPL—and I think we’re still talking about the noise floor >> being the truncation (dithered or not) noise floor for 24-bit—and where is >> the music? At a level few sound systems can sustain, and where you ears >> will be irreparably damaged in short order. Now, you do follow this up with >> saying you can do it with out amplification, to some degree, but clearly >> you wouldn’t have mentioned listening to the noise floor boosted to 60 dB >> SPL if it was remotely close to hearable without amplification. >> >> Anyway, I can agree with you on the technical aspects of correctness, but >> the practical aspects dominate. I think it’s clear that additive dither for >> 24-bit truncation is already fixing a problem that can’t be heard, but it’s >> next to free—either way you’re transporting 24 bits and can’t hear the last >> few, no big deal that we spent a few cpu cycles to “make it right". But I >> have trouble getting excited about taking an unneeded remedy to the next >> level. >> >> Anyway, carry on, still fun to talk about. >> >> > no i think Sampo was wanting to introduce 'subtractive dither' as a > solution, not additive dither - but please correct me if i'm wrong. not > sure about the historical development of dither but i have heard that the > original idea for dither was conceived during WWII when German warplanes > would have problems with the gear assembly becoming stuck, and lubricant > would not help. instead what helped was the occasional random bump to the > gear assembly to help jar things loose and keep things running smoothly > > >> > On Jan 8, 2022, at 12:22 AM, Sampo Syreeni <de...@iki.fi> wrote: >> > >> > On 2022-01-07, Nigel Redmon wrote: >> > >> >> I'm at a loss of how to interpret the importance of "statistically be >> inefficient for measuring purposes”. I don’t think it has much to do with >> 24-bit streaming services, which is what I was addressing. >> > >> > Of course it wouldn't do much there. >> > >> > What I'm talking about is a wholesale solution to all dither needs. >> Including audio, especially of low bitwidths, but then also transmission >> radiotelescope signals and whatever. >> > >> > Because subtractive dither really is the wholesale solution. So good it >> mimics analogue tape at 8 bits, while making 1-bit signals from beyond >> Jupiter better. (Modulo.) >> > >> >> No evidence it’s necessary, even at 16-bit, but certainly not at >> 24-bit which was specifically what I was addressing. >> > >> > Then I missed your point or overspoke. Obviously if you have 24-bit >> accuracy, this stuff mostly won't be necessary. >> > >> > Yet in theory it will be. In theory, even if you have a 24-bit >> quantizer, with ample noise upto the 22-34th bit (the practical limit of >> today's converters), if you look hard enough, you can see the quantization >> underneath. (People do this, you know, in the cryptographic circuit. The >> guys who actually worry about statistical bias. Also, scientific folks, who >> worry about their stochastic sampling code being spot-on, to the umpteenth >> moment.) >> > >> >> If you can’t hear it, or reproduce it—and at 24-bit you get both—you >> can’t hear it. >> > >> > Amplify the noise to 60dB SPL and let me me introduce my favourite test >> signal. Absent subtractive dither, I can introduce audible intermodulation >> products. Even if not amplified, intermodulation products tend to creep up >> off the noise floor, if stable enough. >> > >> >> Ecept I have a pretty good idea of how well it would work, so not much >> point in the experiment—too many other things on the list. :-D >> > >> > Thus, each of us will probably just carry on. It's not as though I'd be >> able to even commecialise thise stuff. :) >> > -- >> > Sampo Syreeni, aka decoy - de...@iki.fi, http://decoy.iki.fi/front >> > +358-40-3751464, 025E D175 ABE5 027C 9494 EEB0 E090 8BA9 0509 85C2 >> > >
