Sound filter information and other documentation

[Supamax]

Originally Posted by Toni Wilen

Which audio filter mode? (none, sinc, anti and so on..)

Hi Toni, sorry if I asked this before (I don't remember): is there somewhere a full WinUAE helpfile/manual thoroughly explaining all the program aspects and parameters?

Just as an example, I don't have a clue about the differences between audio filter sic vs. anti vs. ... etc. etc.

Sorry for this really noob answer , but this can hopefully be useful to someone else here .

P.S. this is almost surely the wrong thread, sorry again

[B14ck W01f]

Originally Posted by Supamax

Hi Toni, sorry if I asked this before (I don't remember): is there somewhere a full WinUAE helpfile/manual thoroughly explaining all the program aspects and parameters?

It would be nice if he decides to add those yellow tooltips in the Adv. Chipset section.

[Toni Wilen]

Tooltips won't help if you don't know Amiga hardware details and if you know hardware details you already know what it means

EDIT: Seriously, Chipset Extra is enough for 98% of use cases, only in very rare experimental cases you need to adjust advanced chipset.

EDIT2: Just ask if you need more information. Most of the advanced chipset checkboxes are really low level and can't be explained shortly.

[Vot]

Originally Posted by Supamax

Hi Toni, sorry if I asked this before (I don't remember): is there somewhere a full WinUAE helpfile/manual thoroughly explaining all the program aspects and parameters?

Just as an example, I don't have a clue about the differences between audio filter sic vs. anti vs. ... etc. etc.

Sorry for this really noob answer , but this can hopefully be useful to someone else here .

P.S. this is almost surely the wrong thread, sorry again

Why don't one of you offer to write the full documentation for him after some research and his guidance/input. Im sure he would rather be doing something else like watch paint dry than write it.

[tero]

there is this online help http://www.vware.at/winuaehelp/
it covers winuae 2.4.0, but is updated every once in a while. It's pretty basic, no detailed explanations about filters etc.

[Nut]

In short - those are different methods on how to perform interpolation of sound. Interpolation is the process of calculating a value in-between two samples of audio. Let's say interpolation point is 0.452 (a value between 0-1), you would calculate linear interpolation of two samples : (B-A)*0.452+A, which is a value somewhere between A and B. This is to smooth the sound and make the resulting soundmix to have better quality (than without interpolation). Mixing audio without interpolation is quite horrible idea, but hey... Amiga does NOT HAVE interpolation (!!), so just forget about it. Set it to disabled. You should never use interpolation for 8bit module music or the Amiga for that matter. WE DID NOT HAVE IT.

Details on Anti, Sinc, RH, Crux could be Googled. I'm not familiar with these but I think Sinc is the best and slowest method (Renoise tracker has this as option).

[Supamax]

Uh, nice, someone (a moderator?) thought my question was interesting and opened a new thread for me . Thanks!

Originally Posted by Vot

Why don't one of you offer to write the full documentation for him after some research and his guidance/input. Im sure he would rather be doing something else like watch paint dry than write it.

Yes, I thought about doing/starting it myself (when I have time...). I fear it involves some very detailed knowledge, as Toni wrote (parameters dealing with very low level aspects).
And the list of added features during the years is so incredibly long... WinUAE is a fantastic emulator!

[Michael Sykes]

Damm thats one complex matter.
And thats only like 0.02% of WinUAE.
Theory of sampling and interpolation alone can fill up some pages even if you take only some important facts to show the reder how it works...
http://eeweb.poly.edu/~yao/EE3414/sampling.pdf

Good luck in writing a full detailed documentation.
I would love to read something like that.And it would be a great benefit for people starting to emulate the amiga after years of abstinence.Time kills a lot of details in the human memory.
And getting some background answers about stuff you didn't even know you had a question about, is allways interesting.

PS: isn't the closest thing to original paula to disable the interpolation?

[Toni Wilen]

Originally Posted by Michael Sykes

PS: isn't the closest thing to original paula to disable the interpolation?

Yes and no. Paula does not need to mix all 4 channels to single output bitrate.

https://bel.fi/alankila/modguide/interpolate.txt (sinc implementation)

[Pecosbil]

Originally Posted by Michael Sykes

PS: isn't the closest thing to original paula to disable the interpolation?

No, AFAIK Paula can playback samples with independent frequencies in all it's channels (like hw synthesizers do) - so, no need for interpolation.

But, if you like to achieve simlair quality with mixing (like UAE for example), you'd have to use interpolation.

[Michael Sykes]

Thanks Toni, that's what I mean with "stuff you didn't even know you had a question about".

Now I understand for example why the DeliTracker 14bit player has 60000Hz mixing frequency. 14.5kHz x 4 = 58000Hz makes sense.
Even if you're just the driver and not the mechanic, it can't be wrong to know how the internals of the engine work.

So from what I understand there can still be some arifacts even with filters enabled.Not as much as without.And with filters is's less noisy but it will lose some "detail" in the worst case. Seems it's really analog to the D3D filters for graphics.

Yes and no. Paula does not need to mix all 4 channels to single output bitrate.

If the Amigas max output without aliasing is 14.5 kHz and we use 48000Hz for the WinUAE output, wouldnt that come really close to the original even without filters?
Would the soundquality improve if you enable the filter at, lets say, 96kHz?

Not that I would be able to hear the difference, just out of curiosity...

[Pecosbil]

Originally Posted by Pecosbil

No, AFAIK Paula can playback samples with independent frequencies in all it's channels (like hw synthesizers do) - so, no need for interpolation.

Ok, after reading Antti Lankila's documentation (that Tony linked above), I must admit being wrong about how Paula produces sound. But, nevertheless, it doesn't have audible aliasing effects with sample rates beyond 28kHz (and probably up to 56kHz with RTG card).

So, unless something like this BLEP resampling is added to WinUAE (like this Protracker clone), you'll need to use some sort of interpolation to avoid aliasing effects.

[Vot]

Originally Posted by Toni Wilen

Yes and no. Paula does not need to mix all 4 channels to single output bitrate.



https://bel.fi/alankila/modguide/interpolate.txt (sinc implementation)

I must admit maybe my assumption of how winuae produced its audio output was wrong. I thought it used no interpolation and mixed at the paula output rate then resampled (using whatever method chosen to the host systems output rate).