Re: [hatari-devel] Sound lowpass filtering?

That's excellent! Thank you. I didn't realize the Falcon was able to run that game; at least I haven't managed to get it to start in Hatari.

I see and hear none of the distortion that is characteristic of the PWMaliasFilter in these, so I feel this confirms my suspicion that it has the same problem.

Otherwise, as previously suggested, they both have much more high frequency content than my STF, closer to the no-filter option. The Falcon has a little less low end. The precise shape of the spectrum is probably a more minor detail, but test program with noise and frequency sweeps, etc. could be used to find a close match.

The main thing is that these do not appear to demonstrate the distortion effect seen in the previous filter implementation, at least for the two machines you've just captured.

-- Brad Smith

On Fri, Sep 1, 2023 at 3:35 PM Anders Eriksson <evldhs@xxxxxxxxxxxxxx> wrote:

------- Original Message -------
On Friday, September 1st, 2023 at 18:42, Brad Smith <rainwarrior@xxxxxxxxx> wrote:

I would suggest the Bubble Bobble title screen and intro (the little jingle that plays after pressing 1 to start the game) to compare against what I already have. Unfortunately I don't think it's compatible with the Falcon though.

Hello,

Falcon headphone jack:
https://www.dropbox.com/scl/fi/o7q3nfn5vsrg1haqa2z0s/Falcon_Headphone.wav?rlkey=5oiqyur8dccj2zojak4r6zp6w&dl=1

STe RCA jacks:
https://www.dropbox.com/scl/fi/8wn0c18glm41qbbbolkv0/STe-RCA.wav?rlkey=dbkmry8j2x122et42e9g8c1eg&dl=1

Hope it helps.

--
Anders Eriksson
ae@xxxxxx

Otherwise any game with good title screen music would probably be good for comparison.

I'll put on my to-do list writing a program that does a more direct walkthrough of the YM sound features (frequency sweep, flat tones, etc.) which could be used for better reference comparisons.

-- Brad

On Fri, Sep 1, 2023 at 12:16 PM Anders Eriksson <evldhs@xxxxxxxxxxxxxx> wrote:

As stated, I do not have experience with STE or Falcon, and I also have found verifiable hardware recordings much more difficult to come by for these machines (especially Falcon), so I can't make any empirical argument about the PWMaliasFilter. I only suspect that it may have the same problem as the LowPassFilter, since it is structurally a very similar filter implementation.

Hi,

I can record from a Falcon and STe.
My ADC is a rather lowcost USB one so quality is likely not the absolute best.

If you like something recorded, please inform me of what.

--
Anders Eriksson
ae@xxxxxxx

-- Brad Smith

On Fri, Sep 1, 2023 at 5:57 AM Nicolas Pomarède <npomarede@xxxxxxxxxxxx> wrote:
Le 01/09/2023 à 10:19, Nicolas Pomarède a écrit :
> 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 :)
>

So, I had time to listen to your flac recordings. I must admit that for
the first part of the audio I don't hear that much difference/distortion.

But it's true that at +12 sec there're 7 separate notes where a
difference can be heard between the different files and hatari 2.4.1
sounds more distorted than 1040stf

Just a question regarding the recordings made with Hatari : for these 4
recordings, did you also apply the change to move the filter in
YM2149_NextSample_250() (as you describe in issue #1 of your PR) ?
In case I want to do recordings myself to compare with yours, I need to
have filter applied at the same point as you did.

Nicolas