Re: [hatari-devel] Sound lowpass filtering?

[Nicolas Pomarède <npomarede@xxxxxxxxxxxx>]

Le 31/08/2023 à 20:04, Brad Smith a écrit :
> Hello. This is my first post to the mailing list, so I hope I have done 
> this correctly.
>
>  > but it's sure very interesting to have an updated patch since going 
> to 250 kHz, having better filtering can be a complicated task depending 
> on which HW we try to emulate and how much CPU we want to dedicate to 
> this part.
>
> The change made in my pull request actually lowers the CPU usage. It is 
> not trying to produce a more complicated hardware model that would 
> require extra computation, but rather the opposite.
>
> Summary:
> - Fix the lowpass filters which have been broken since the move to 250 
> kHz. The audio output has essentially been unfiltered since that time.
> - Provide a simplified lowpass filter model as a default, because I 
> believe the two existing ones are flawed and not representative of the 
> hardware sound they attempt to model.
>
> Full details of the patch, with sound examples and explanation are here: 
> https://github.com/hatari/hatari/pull/25 
> <https://github.com/hatari/hatari/pull/25>

Hi

welcome to the list.

I still didn't have time to check the wav recordings you made as well as 
the patches, but it's on the top of my todo list so it won't be forgotten ;)

In case David Savinkoff (who wrote the original sound filters for 
Hatari) reads the list, maybe he can comment on your changes and the 
differences / improvements you hear.

Nicolas