Re: [hatari-devel] Sound lowpass filtering?

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 01/09/2023 à 03:45, Brad Smith a écrit :

> It's been a little bit frustrating that nobody has commented on the 
> sound recordings at all. Has anyone listened to them? Has anyone 
> analyzed them? Do you have subjective feelings about their quality as I 
> do? Do you think my evidence is wrong? Do you have recordings of your 
> own? Do you have an ST that sounds more like LowPassFilter? Has anyone 
> built my proposed changes and listened to them?

Hi

on my side, as I wrote on atari-forum, I was in holidays away from home 
with no correct speakers to do proper listening. Back home now, I will 
try to listen to your recording asap, but I have lot of "real" work at 
the moment, very few spare time, so please allow a little more delay :)

But I'm *really* interested in getting as much perfect emulated sound in 
Hatari as possible.

If you look at the sound emulation part, you can see that there were 
several big rewrites over time, using many custom programs that I ran on 
my STF to better understand how counters are updated in the YM2149 and 
what the effect of changing them "on the fly" (which as far as I know 
had never been properly measured/documented before in other emulators 
using YM2149)

Also I would not have rewritten everything again to get cycle "accurate" 
250 kHz emulation if I was not interested to get as perfect sound as 
possible and support all effects used in recent maxymizer for example.

Now when it comes to filtering and its general theory I must admit that 
this is not my main field of expertise, so I'm more than happy to rely 
on other people who have better understanding of these models and how to 
emulate filtering in the best way possible.

In the end, it does of course matter that emulated audio sounds like 
real STF/STE audio and we need tyo be pragmatic about this, but it would 
be even more satisfying to have a theoretical model for the filter's 
parameters that can be built from looking at the STF's hardware 
components and give the same audio results.

Nicolas